Residual levels and dietary exposure risk assessment of banned pesticides in fruits and vegetables from Chinese market based on long-term nontargeted screening by HPLC-Q-TOF/MS

The negative impact of banned pesticides is of special importance for their high toxicity. In this study, nationwide screening of banned pesticides in 37462 fruit and vegetable samples was carried out from 2012 to 2018 using a self-developed HPLC-Q-TOF/MS technique. The dietary exposure risks associated with the banned pesticides were assessed. The results showed that 66.62 % of the samples were detected at least one pesticide. Among the pesticide-positive samples, a total of 18 banned pesticides were detected in 1798 samples for 1896 times. The risk assessment revealed that 11.71 % of the positive detections exceeded the safety limits and posed an unacceptable risk, while 37.29 % of the positive detections posed acceptable risks. According to the screening and assessment results, two national maps were presented to show the total detection ratios of the banned pesticides and the unacceptable risks of dietary exposure. It should be noted that omethoate had higher residual concentration, unacceptable risk frequency and unacceptable risk proportion. This is the first nationwide comprehensive report on screening and risk assessment banned pesticides.

Efficiency and mechanism of C18-functionalized magnetic nanoparticles for extracting weakly polar pesticides from human serum determined by UHPLC-QTOF-MS and molecular dynamics simulations

Detecting pesticide residues in human serum is a challenging process due to trace-level chronic exposure. Several methods using magnetic adsorbents have been developed for analyzing pesticide residue levels in human serum, but it is still difficult to achieve lower quantitative levels, and the adsorption mechanism for extracting pesticides is unclear. Herein, we propose a feasibility concept of using C₁₈-functionalized magnetic nanoparticles for the adsorption of target pesticides, focusing on the extensively used weakly polar pesticides based on molecular dynamics (MD) simulations. To support this, the facilitated target nanoparticles of Fe₃O₄@SiO₂-C₁₈ were synthesized at a size of 12-13 nm with a magnetic saturation of 40 emu/g. After optimizing and establishing the extraction conditions (1.8 mL C₁₈ modifier, 10 mg sorbents, 3 min adsorption time, 1000 μL ACN for desorption eluent at pH 3.8 and 5 min desorption time), which exhibited recovery = 72.3%-118.3% with RSDs = 0.03-6.57, linearity at 0.01-10 ng/mL with R² = 0.9561-0.9993, and LODs = 0.01-0.30 ng/mL for the 11 weakly polar pesticides in human serum. Furthermore, the mechanism by which the C₁₈ group selectively extracts weakly polar pesticides was confirmed by binding van der Waals and electrostatic interactions under stable and strong binding energy. The extraction process of efficient adsorption and desorption with C₁₈ functional magnetite nanoparticles suggests a simple method for detecting weakly polar pesticides. The concept may lead to a general approach to analyzing multiple pesticide residues in human serum at trace levels.

[Assessment of cognitive function of the elderly by serum metabolites of brain-gut axis]

Objective: To investigate the feasibility of assessing cognitive function of the elderly by serum metabolites of brain-gut axis. Methods: Convenience sampling was used to select 100 and 60 participants from the healthy population cohort and microecological balance cohort of the longevity population in Guangxi, to constitute subset of healthy population and longevity population, respectively. A questionnaire was used to investigate the demographic characteristics of the subjects, 2-5 ml of fasting venous blood was collected from the subjects, and the serum untargeted metabolomics was determined by liquid chromatography tandem mass spectrometry. The biomarkers related to the brain-gut axis were collected through literature retrieval, and the results were intersected with the untargeted metabolites and annotated. Spearman correlation analysis was used to screen serum metabolites of brain-gut axis associated with aging, and multiple linear regression method was used to construct biological age model. The mini mental status examination was used to evaluate the cognitive function of longevity population subsets. The differences of biological age and chronological age of longevity population subsets with different cognitive function were compared. Results: The M (Q₁, Q₃) of subset of healthy population and longevity population were 64 (38, 72) and 97 (95, 99) years old, respectively, and there were 50 (50.0%) and 44 (73.3%) females, respectively. Nine serum metabolites of brain-gut axis were obtained by initial screening, which were propionic acid, glutamic acid, γ-aminobutyric acid (GABA), lactic acid, 5-hydroxytryptamine (5-HT), tryptophan, trimethylamine oxide, dopamine and canine urea. Spearman correlation analysis showed that glutamic acid and dopamine were positively correlated with aging (r values were 0.208 and 0.524, respectively, all P values<0.05), and tryptophan, 5-HT and GABA were negatively correlated with aging (r values were -0.308, -0.533 and -0.213, respectively, all P values<0.05). The biological age model was constructed as: y=49.81-1.18×10^-5× GABA-1.82×10^-4×5-HT+1.99×10^-3×dopamine+1.65×10^-6×glutamic acid -2.04×10^-6×tryptophan+2.36×gender, where y was the biological age (years), the items on the right were the intercept item, the relative concentration of each metabolite, and gender (male=1, female=2). The coefficient of determination of model was 0.50 (P<0.001). The M (Q₁, Q₃) of the chronological age of the subset of longevity population with poor, moderate and good cognitive function were 97 (94, 100), 97 (93, 101) and 96 (94, 101) years old, respectively, and there was no statistical significance in pairwise comparison (all P values>0.05). The M (Q₁, Q₃) of the biological age of the subjects with better cognitive function was 51 (38, 54) years old, which was lower than that of the subjects with poor cognitive function [57 (47, 61)] (P=0.040). Conclusion: The biological age model can be constructed based on serum metabolites of brain-gut axis and used to evaluate the cognitive function of the elderly.

[An epigenetic clock model for assessing the human biological age of healthy aging]

Objective: To construct an epigenetic clock model for assessing and calibrating human biological age. Methods: Convenience sampling was used to select 186 subjects from the longevity cohort of Guangxi Zhuang Antonornous Region from July 1 to November 30, 2019, and 124 subjects from the physical examination population of the Seventh Medical Center of the PLA General Hospital from October 1 to December 31, 2020. Self-designed questionnaire was applied to collect demographic characteristics and family history of disease. Physical examination was applied to determine heart rate and blood pressure. Fasting peripheral venous blood was drawn for determination of fasting plasma glucose, plasma total cholesterol, triglyceride, plasma high-density lipoprotein cholesterol, plasma low-density lipoprotein cholesterol and telomere length. Methylation levels of EDARADD cg09809672, IPO8 cg19722847, NHLRC1 cg22736354, P2RX6 cg05442902 and SCGN cg06493994 were detected by targeted methylation site sequencing. A total of 54 subjects with unqualified quality control of DNA methylation and telomere length were excluded, and 256 subjects' data were finally analyzed. Trend test was used for the change of methylation level among different ages groups, multiple linear regression method was used to build prediction models of biological age. Kendal rank correlation analysis was used to evaluate the correlation of age gap (Gregorian calendar age minus biological age) with telomere length. Independent sample t-test was used to compare the health-related indicators between subjects with different age gap within different age groups. Results: The M(Q₁, Q₃)of age of subjects were 67 (51, 91) years old, including 166 females (64.84%). With increase of age, the methylation levels of gene loci were decreased (EDARADD cg09809672, IPO8 cg19722847 and P2RX6 cg05442902) and increased (NHLRC1 cg22736354 and SCGN cg06493994) (all P values<0.05). The established biological age prediction model was as follows: Y=-53.121×EDARADD cg09809672-137.564×IPO8 cg19722847+141.040×NHLRC1 cg22736354-67.893×P2RX6 cg05442902+149.547×SCGNcg06493994+4.592×sex+64.185 (R²=0.86, P<0.001), where Y was the biological age, and the items in the equation were methylation level, sex (male =1, female =2) and intercept in sequence. The Kendall rank correlation coefficient between age gap and telomere length was 0.731 (P<0.001). Compared with the subjects whose age gaP<0, the subjects with age gaP≥0 had higher systolic blood pressure in adolescence [(88.50±8.89) and (109.83±9.48) mmHg, respectively, 1 mmHg=0.133 kPa]; lower TC [(5.48±0.23) and (3.98±0.54) mmol/L, respectively, ] and TG [(3.51±0.32) and (3.41±0.20) mmol/L] in young adults; lower fasting blood glucose in middle age [(6.17±0.67) and (5.37±0.79) mmol/L, respectively, ] and higher diastolic blood pressure in nonagenarian age [(76.99±6.78) and (83.97±9.36) mmHg, respectively, ] (all P values<0.05). Conclusion: The constructed epigenetic clock model can be used to evaluate and calibrate human biological age.

Multilaboratory Collaborative Study of a Nontarget Data Acquisition for Target Analysis (nDATA) Workflow Using Liquid Chromatography-High-Resolution Accurate Mass Spectrometry for Pesticide Screening in Fruits and Vegetables

Nontarget data acquisition for target analysis (nDATA) workflows using liquid chromatography-high-resolution accurate mass (LC-HRAM) spectrometry, spectral screening software, and a compound database have generated interest because of their potential for screening of pesticides in foods. However, these procedures and particularly the instrument processing software need to be thoroughly evaluated before implementation in routine analysis. In this work, 25 laboratories participated in a collaborative study to evaluate an nDATA workflow on high moisture produce (apple, banana, broccoli, carrot, grape, lettuce, orange, potato, strawberry, and tomato). Samples were extracted in each laboratory by quick, easy, cheap, effective, rugged, and safe (QuEChERS), and data were acquired by ultrahigh-performance liquid chromatography (UHPLC) coupled to a high-resolution quadrupole Orbitrap (QOrbitrap) or quadrupole time-of-flight (QTOF) mass spectrometer operating in full-scan mass spectrometry (MS) data-independent tandem mass spectrometry (LC-FS MS/DIA MS/MS) acquisition mode. The nDATA workflow was evaluated using a restricted compound database with 51 pesticides and vendor processing software. Pesticide identifications were determined by retention time (t_R, ±0.5 min relative to the reference retention times used in the compound database) and mass errors (δ_M) of the precursor (RTP, δ_M ≤ ±5 ppm) and product ions (RTPI, δ_M ≤ ±10 ppm). The elution profiles of all 51 pesticides were within ±0.5 min among 24 of the participating laboratories. Successful screening was determined by false positive and false negative rates of <5% in unfortified (pesticide-free) and fortified (10 and 100 μg/kg) produce matrices. Pesticide responses were dependent on the pesticide, matrix, and instrument. The false negative rates were 0.7 and 0.1% at 10 and 100 μg/kg, respectively, and the false positive rate was 1.1% from results of the participating LC-HRAM platforms. Further evaluation was achieved by providing produce samples spiked with pesticides at concentrations blinded to the laboratories. Twenty-two of the 25 laboratories were successful in identifying all fortified pesticides (0-7 pesticides ranging from 5 to 50 μg/kg) for each produce sample (99.7% detection rate). These studies provide convincing evidence that the nDATA comprehensive approach broadens the screening capabilities of pesticide analyses and provide a platform with the potential to be easily extended to a larger number of other chemical residues and contaminants in foods.

Spermiogenesis toxicity of imidacloprid in rats, possible role of CYP3A4

This study evaluated the adverse effects of low-dose imidacloprid (IMI) on the characteristics of sperm from male Wistar rats. Thirty mature male rats were equally divided into three groups and orally administered vehicle (Control Group), acceptable daily intake (ADI) concentration of IMI (Group 1), and IMI at a dose 10-fold that of the ADI (Group 2) for 90 days. The findings revealed that IMI caused abnormalities in sperm concentrations and morphologies, accompanied by an imbalance of the gonadal hormone testosterone. Histopathological damage and decrease of testosterone levels were observed in testes from rats treated with IMI. However, estradiol and gonadotropin levels were unchanged after IMI treatment. IMI inhibited the activity of cytochrome P450 3A4 (CYP3A4) and left itself existed in the organism of rats. The indicators relating to sperms and CYP3A4 activity were recovered when rats were co-treated with IMI and CYP3A4 inducer rifampicin together. These results indicated that low-dose IMI exposure caused sperm abnormalities through affecting on the spermiogenesis in testis. Inhibition of CYP3A4 activity by IMI largely contributed to its sperm toxicity. Thus, IMI exposure at doses close to real-world settings resulted in sperm toxicity on rats, which might be a potential risk factor for human reproductive diseases.

Imidacloprid increases intestinal permeability by disrupting tight junctions

The neonicotinoid pesticide, imidacloprid (IMI), is frequently detected in the environment and in foods. It is absorbed and metabolized by the intestine; however, its effects on intestinal barrier integrity are not well studied. We investigated whether IMI disrupts the permeability of the intestinal epithelial barrier via in vivo tests on male Wistar rats, in vitro assays using the human intestinal epithelial cell line, Caco-2, and in silico analyses. A repeated oral dose 90-day toxicity study was performed (0.06 mg/kg body weight/day). IMI exposure significantly increased intestinal permeability, which led to significantly elevated serum levels of endotoxin and inflammatory biomarkers (tumor necrosis factor-alpha and interleukin-1 beta) without any variation in body weight. Decreased transepithelial electrical resistance with increased permeability was also observed in 100 nM and 100 μM IMI-treated Caco-2 cell monolayers. Amounts of tight junction proteins in IMI-treated colon tissues and between IMI-treated Caco-2 cells were significantly lower than those of controls. Increased levels of myosin light chain phosphorylation, myosin light chain kinase (MLCK), and p65 subunit of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB p65) phosphorylation were found in IMI-exposed cells compared with control cells. Furthermore, the barrier loss caused by IMI was rescued by the MLCK inhibitor, ML-7, and cycloheximide. Pregnane X receptor (PXR, NR1I2) was inhibited by low-dose IMI treatment. In silico analysis indicated potent binding sites between PXR and IMI. Together, these data illustrate that IMI induces intestinal epithelial barrier disruption and produces an inflammatory response, involving the down-regulation of tight junctions and disturbance of the PXR-NF-κB p65-MLCK signaling pathway. The intestinal barrier disruption caused by IMI deserves attention in assessing the safety of this neonicotinoid pesticide.

Triazophos and its metabolite diethyl phosphate have different effects on endocrine hormones and gut health in rats

Organophosphorus pesticide (OP) residues present in food can be metabolized into diethylphosphate (DEP) in vivo. Epidemiological studies of OPs have usually focused on these metabolites, while animal studies mainly assessed the OPs. Here, we compared the health risks of a frequently detected OP, triazophos (TAP), and its major metabolite, DEP, in rats. Levels of serum lipids and, sex hormones were measured using immunoassay kits. Gut hormones and inflammatory cytokines were assessed using a multiplexing kit, and the gut microbiota was evaluated by 16S rRNA gene sequencing. After a 24-week exposure period, both TAP and DEP significantly decreased serum levels of triglycerides, cholesterol, low-density lipoprotein cholesterol, and IL-6 (p < 0.05). However, DEP exposure had a stronger effect on serum estradiol (p < 0.05) than TAP, whereas only TAP inhibited the secretion of gut hormones. Both TAP and DEP enriched the pathogenic genera Oscillibacter, Peptococcus and Paraprevotella in the gut, and TAP also enriched enteritis-related genera Roseburia and Oscillibacter, which may affect the secretion of gut hormones. These findings indicate that the use of dialkyl phosphates as markers of OPs to examine the correlations of OP exposure with diseases may only provide partial information, especially for diseases related to gut health and the endocrine system.

[Analysis of distribution characteristics and influencing factors of healthy and long-lived people in Shanglin area of Nanning, Guangxi Zhuang Autonomous Region]

Objective: To explore the epidemiologic characteristics of long-lived population and influencing factors in Shanglin county of Guangxi and provide scientific basis for the study of health and longevity in Guangxi. Methods: We collected and analyzed the general demographic cross-sectional data of the long-lived individuals (≥90 years old) in 11 villages and towns by multi-source registration and face-to-face interview. The age group control design was adopted to conduct a comparison among the longevity group (90-100 years old), centenarian group (≥100 years old), the longevity plus centenarian group and control group (local population aged 40-85 years), and identify the factors related to longevity. Results: Among the 496 007 people registered in Shanglin, 1 533 were aged ≥90 years, including 1 453 in the longevity group, with an average age of (92.84±2.46) years, and 80 in the centenarian group, with an average age of (102.67±2.60) years. The spatial distribution of long-lived individuals and centenarians was mainly in the north and central areas, and sparse in southwest area. Analysis on factors related to health and longevity indicated that old people with Zhuang ethnic (OR=1.551,95%CI:1.308-1.838), married (OR=55.507,95%CI:36.087-85.377) and moderately high waist-to-hip ratio (OR=258.056,95%CI:27.775-2 397.569), and SBP (OR=1.019,95%CI:1.013-1.026) tended to live longer. Conclusions: We found that the rate of longevity in Shanglin was higher than the average level in Guangxi and China. Longevity in Shanglin country had unique spatial and population distribution characterics of female longevity more than male longevity, mainly Zhuang ethnic and so on. Being women, married, family history of longevity, appropriate high waist-to-hip ratio, SBP and blood sugar level might be positive factors for longevity in Shanglin, but the impacts of other factors on longevity need further study.

[Efficacy and safety of Kangbingdu granules in the treatment of influenza: a randomized, double-blind, double-dummy, positive-drug parallel control multicenter clinical trial]

Objective: To observe the efficacy and safety of Kangbingdu granules (KBD) in the treatment of influenza. Methods: A multicenter, randomized, double-blind, double-dummy, and positive-drug parallel control trial was conducted in 27 Grade ⅢA hospitals in China and the subjects were randomly assigned to the KBD test group or the oseltamivir phosphate capsule control group at a ratio of 1∶1. 200 subjects were planned to be enrolled in each group. The experimental group was given KBD (18g each time, 3 times a day) and oseltamivir phosphate simulator orally, while the control group was given oseltamivir phosphate capsule (75 mg each time, twice a day) and KBD simulator orally for 5 days. The primary efficacy indicators included the remission time of major clinical symptoms and the time of complete defervescence. The secondary efficacy indicators included dosage of acetaminophen, the change of traditional Chinese medicine (TCM) syndrome score and the remission time of other important clinical symptoms. The efficacy of KBD in the test group and Oseltamivir phosphate control group were compared. Adverse events or adverse reactions were observed at the same time to evaluate the safety of KBD Granules. Results: A total of 393 subjects from 27 Grade ⅢA hospitals in China were enrolled. The experimental group included 195 subjects and 191 subjects (97.95%) completed the trial, While the control group included 198 subjects and 195 subjects (98.48%) completed the trial. There was no significant difference in the shedding rate and rejection rate between the two groups (P>0.05). In the Full Analysis Set (FAS), the mean age of the experimental group was (34.9±14.4) years old, with 83 males (42.78%). The mean age of the control group was (33.3±13.5) years old, with 78 males (39.59%). There were no statistically significant differences between the two groups in demographic data, physical examination, viral pathogen detection, total score of TCM syndromes and scores of each symptom at baseline (P>0.05). In the FAS, the remission time M (Q₁, Q₃) of major clinical symptoms was 3.0 (3.0, 4.0) days in the experimental group and 3.0 (3.0, 4.0) days in the control group, and the difference was not statistically significant (P>0.05). The time M (Q₁, Q₃) of complete defervescence was 34.0 (20.3, 49.0) hours in the experimental group and 36.5 (19.6, 48.8) hours in the control group, and the difference was not statistically significant (P>0.05). KBD granules had the same effect as Oseltamivir phosphate capsule (P>0.05) in terms of acetaminophen dosage, TCM syndrome effect and disappearance rate of most important clinical symptoms. Meanwhile, the disappearance rate of dizziness and chest distress on day 3 in the KBD granules group was better than that of oseltamivir phosphate capsule (P<0.05). Conclusion: KBD granules have the same efficacy as Oseltamivir Phosphate capsule in the treatment of influenza and the drug safety is good.

[The study on the distribution characteristics and relevant factors of healthy and long-lived people in multiple regions of Guangxi Zhuang Autonomous Region]

Objective: To investigate the epidemiological characteristics and relevant factors among individuals characterized by their longevity in multiple regions of Guangxi Zhuang Autonomous Region, and provide a valuable scientific perspective for the research in health and longevity of the elderly in Guangxi. Methods: Registration and face-to-face questionnaire on a door-to-door basis were adopted to collect the demographic characteristics of the long-lived individuals (≥90 years old) in Bama of Hechi city, Yongfu of Guilin city, Dongxing of Fangchenggang city, Guangxi. Then, among the local general population, individuals within the age group between 40 and 85 years old were selected randomly as controls. Correlations were then analyzed between the relative health and longevity of the subjects and their gender, ethnicity, family history, disease history, marital status, the number of family generations, the number of children, smoking, drinking, outdoor activities, sleep and other health-related factors, then the result was subject to further analysis by comparing the long-lived population and the control population respectively. Results: Among 691 500 of the permanent residents of Bama, Yongfu and Dongxing city, 1 005 cases were 90 years old and over with a ratio of 145.34 out of 100 000 persons; within the 1 005 cases, 944 were aged between 90 and 100 (longevity rate: 136.51/100 000) with an average age of (93.28±2.57); 61 cases were aged 100 or over, arriving at a centenarian rate of 8.82/100 000 with an average age of (102.00±3.05) years. Significant differences were found just among three particular factors - regional distribution (P=0.014), history of disease (P=0.002), four generations of family (P=0.008) between nonagenarians and centenarians (P<0.05), while the other 15 indicators did not show anything noteworthy. The result indicated that longevity and centenarians might be the same group and then we combined both groups into one. By cross-comparison between the longevity-plus- centenarians and the control group in the region, factors listed below exhibited significant correlation with health and longevity: marital status (OR=26.469, 95%CI: 13.208-53.045), number of generations within the family (OR=5.419, 95%CI: 3.418-8.592), number of male offspring (OR=2.013, 95%CI: 1.555-2.607), number of female offspring (OR=1.380, 95%CI: 1.122-1.696), and the frequency of outdoor activities (OR=10.226, 95%CI: 3.164-33.045). Conclusions: The longevity rate is higher in the general natural population in Bama, Yongfu and Dongxing of Guangxi. The phenomenon may owe to favorable family structure, atmosphere within or out of the family or other elements related with social surrounding. Among them all, mentality, inclination to physical exercise and regular rhythm of life may all exert tremendous contributory influence here.

Toxicities of Neonicotinoid-Containing Pesticide Mixtures on Nontarget Organisms

Neonicotinoids are a widely used class of pesticides. Co-exposure to neonicotinoids and other classes of pesticides can exert potentiating or synergistic effects, and these mixtures have been detected in human bodily fluids. The present review summarizes studies into the effects of neonicotinoid-containing pesticide mixtures on humans and other nontarget organisms. Exposure to these mixtures has been reported to result in reproductive and hormonal toxicity, genotoxicity, neurotoxicity, hepatotoxicity, and immunotoxicity in vertebrates. Mortality of pollinators and toxicity in other organisms has also been reported. The underlying mechanism of pesticide mixture toxicity may be associated with impairment of cytochrome 450 enzymes, which are involved in metabolizing pesticides. However, a comprehensive explanation of the adverse effects of neonicotinoid-containing pesticide mixtures is still required so that effective prevention and control measures can be formulated. Environ Toxicol Chem 2020;39:1884-1893. © 2020 SETAC.

Assessment of the endocrine-disrupting effects of diethyl phosphate, a nonspecific metabolite of organophosphorus pesticides, by in vivo and in silico approaches

Organophosphorus pesticides (OPs) remain one of the most commonly used pesticides, and their detection rates and residues in agricultural products, foods and environmental samples have been underestimated. Humans and environmental organisms are at high risk of exposure to OPs. Most OPs can be degraded and metabolized into dialkyl phosphates (DAPs) in organisms and the environment, and can be present in urine as biomarkers for exposure to OPs, of which diethyl phosphate (DEP) is a high-exposure metabolite. Epidemiological and cohort studies have found that DAPs are associated with endocrine hormone disorders, especially sex hormone disorders and thyroid hormone disorders, but there has been no direct causal evidence to support these findings. Our study explored the effects of chronic exposure to DEP on endocrine hormones and related metabolic indicators in adult male rats at actual doses that can be reached in the human body. The results showed that chronic exposure to DEP could cause thyroid-related hormone disorders in the serum of rats, causing symptoms of hyperthyroidism in rats, and could also lead to abnormal expression of thyroid hormone-related genes in the rat liver. However, DEP exposure did not seem to affect serum sex hormone levels, spermatogenesis or sperm quality in rats. The molecular interactions between DEP and thyroid hormone-related enzymes/proteins were investigated by molecular docking and molecular dynamics methods in silico. It was found that DEP could strongly interact with thyroid hormone biosynthesis, blood transport, receptor binding and metabolism-related enzymes/proteins, interfering with the production and signal regulation of thyroid hormones. In vivo and in silico experiments showed that DEP might be a potential thyroid hormone-disrupting chemical, and therefore, we need to be more cautious and rigorous regarding organophosphorus chemical exposure.

Packed-Column Gas Chromatographic Method for the Simultaneous Determination of 10 Pyrethroid Insecticide Residues in Fruits, Vegetables, and Grains

A simple, rapid, packed-column gas chromatographic method was developed for simultaneous determination of 10 pyrethroid insecticide residues (allethrin, biphenthrin, cyhalothrin, permethrin, cyfluthrin, flucythrinate, fenvalerate, fluvalinate, deltamethrin, and py-115) in fruits, vegetables, and grains. These multiresidues are extracted from various crops with acetone–petroleum ether and cleaned up on a Florisil column (for the fruits and vegetables) or on a Florisil–charcoal–alumina column (for the grains) prior to their determination by gas chromatography with an electron capture detector. Recoveries of 10 pyrethroid compounds from 12 different crops (maize, soybeans, wheat, sorghums, paddy, potatoes, cucumbers, cauliflowers, spinaches, apples, bananas, and oranges) fortified at levels of 0.02–5.00 ppm ranged from 58 to 130%. In a separate precision study, coefficients of variation were 5.5–14.6% at 0.1–0.5 ppm (n = 10, maize), and 4.1–12.1% at 0.010–0.050 ppm (n = 10, apples). The detection limits of the method ranged from 2.0 to 10.0 ppb on a crop basis.

Modification of AOAC Multiresidue Method for Determination of Synthetic Pyrethroid Residues in Fruits, Vegetables, and Grains. Part I: Acetonitrile Extraction System and Optimization of Florisil Cleanup and Gas Chromatography

We present a multiresidue method for determination of synthetic pyrethroids in fruits, vegetables, and grains. The method is a modification of AOAC Method 970.52. Residues are extracted with acetonitrile (for fruits and vegetables) or acetonitrile–water (2 + 1) (for grains) and then transferred to hexane. Coextractives are removed by acetonitrile partitioning and open-column chromatography with deactivated Florisil. The final extract is analyzed by gas chromatography with electron capture detection (GC–ECD). An HP-17 wide-bore column is used to determine the total isomeric content of each insecticide, and a DB-5 narrow-bore column is used to determine the individual isomeric contents of each insecticide. The method was used to recover 8 pyrethroids (biphenthrin, fenpropathrin, cyhalothrin, permethrin, cypermethrin, fluvalinate, fenvalerate, and deltamethrin) spiked at 0.01–4.0 mg/kg in 20 crops (apple, pear, peach, banana, grape, strawberry, potato, tomato, cucumber, pepper, cabbage, carrot, celery, polished rice, wheat, green gram, buckwheat, sorghum, maize, and barley). Recoveries of the 8 pyrethroid insecticides in 6 crops ranged from 83.8 to 112.8%, with a coefficient of variation (CV) of 2.00 to 12.09% for the narrow- bore capillary GC (n = 6) and from 82.8 to 106.4%, CV = 2.93–12.19%, for the wide-bore capillary GC (n = 6). The minimum detectable levels of 0.004–0.028 mg/kg (for fruits and vegetables) or 0.01–0.08 mg/kg (for grains) for the 8 pyrethroids are easy to detect.

Modification of AOAC Multiresidue Method for Determination of Synthetic Pyrethroid Residues in Fruits, Vegetables, and Grains. Part II: Acetone Extraction System

To optimize conditions and to evaluate further a multiresidue method for pyrethroids, various extraction solvents and partitioning conditions were examined. Acetone and acetonitrile (for fruits and vegetables) and acetone–water and acetonitrile–water (for grains) were used as solvents with or without acetonitrile partitioning. Twenty crops fortified with 8 pyrethroid insecticides at low, medium, and high levels were analyzed. For limit of detection (LOD) levels, repeatability tests were completed with acetone–water as extraction solvent. Recoveries of 8 pyrethroid insecticides at LOD levels were 76.2–99.6%, with coefficients of variation (CVs) of 2.08–10.90% for narrow-bore capillary gas chromatography (GC) (n = 6) and 80.1–107.3% with CVs of 3.76–15.38% for wide-bore capillary GO (n = 6). Both acetone or acetone–water extraction with acetonitrile partitioning and acetonitrile or acetonitrile–water extraction with acetonitrile partitioning are suitable for multiresidue analysis of pyrethroid insecticides. However, acetonitrile and acetonitrile– water as extraction solvents were better than acetone and acetone–water at LOD-fortified levels. This finding was confirmed chromatographically with pear, cucumber, and barley control samples.

Multiresidue Liquid Chromatographic Method for Simultaneous Determination of Pyrethroid Insecticides in Fruits and Vegetables

A simple and rapid liquid chromatographic (LC) method has been developed for simultaneous determination of 9 pyrethroid insecticides (biphenthrin, cypermethrin, fenpropathrin, fenvalerate, flucythrinate, methothrin, permethrin, py-115, and tetramethrin) in fruits and vegetables. Residues are extracted from crops with methanol and partitioned with toluene. Extracts are cleaned up by Florisil–charcoal column chromatography. LC separation is performed on a μBondapak C18 stainless steel column with acetonitrile–deionized water as mobile phase. The insecticides are detected at 206 nm with 0.03 absorbance unit full scale. Recoveries of 9 pyrethroid insecticides from 6 crops (cucumbers, tomatoes, cabbages, apples, pears, and peaches) fortified at 0.5–5.0 mg/kg were 62.7–129.2%. Detection limits were about 0.05 mg/kg, except for py-115, for which detection limit was 0.10 mg/kg.

Modification of AOAC Multiresidue Method for Determining Synthetic Pyrethroid Residues in Fruits, Vegetables, and Grains. Part III: Studies of Analyte Stability and Method Ruggedness

The stability of 8 synthetic pyrethroids in 9 crops during storage for 90 days were studied. The 8 pyrethroid insecticides were highly persistent in the 6 grains during storage. But their stabilities in 3 kinds of fruits and vegetables were different from those in the 6 grains: Most of them were degraded. Florisil purification conditions were studied with 6 batches of Florisil from 3 countries at various extents of deactivation and amounts. The best conditions of Florisil purification found in this present research agree with those found 1 year ago. The efficiencies of acetonitrile and acetone to extract the 8 pyrethroids from 6 fruit and vegetable samples were compared. The extraction efficiency of acetone was competitive with that of acetonitrile for the 6 fruit and vegetable samples. Method performance was evaluated by 6 analysts from different areas. The ruggedness tests demonstrate further that the proposed method is simple, accurate with good precision, and suitable for multiresidue analysis of pyrethroids in various agriculture products.

Cleanup with Two Florisil Columns for Gas Chromatographic Determination of Multiple Pyrethroid Insecticides in Products of Animal Origin

A gas chromatographic method was developed for the simultaneous determination of 9 pyrethroid insecticides in products of animal origin. The multiresidues of the pyrethroids in different samples were extracted with acetone–petroleum ether (1+1), and extracts were cleaned up on a Florisil partition column and a Florisil adsorption column. Four animal tissue samples were examined at 0.05–0.25 ppm fortification levels. The average recoveries of all insecticides were 76.9–88.0%, and the coefficients of variation were &lt;4.6% for all insecticides except permethrin. The detection limits of the method were ca 5 ppb for all insecticides but permethrin, which had a detection limit of ca 10 ppb.

Analysis Method Study on 839 Pesticide and Chemical Contaminant Multiresidues in Animal Muscles by Gel Permeation Chromatography Cleanup, GC/MS, and LC/MS/MS

The paper reports the study of gel permeation chromatography (GPC), gas chromatography/mass spectrometry (GS/MS), and column chromatography tandem MS (LC/MS/MS) for 839 pesticides and chemical contaminants, through which a GPC data bank has been established for 744 pesticides, a GC/MS data bank for 541 pesticides, and an LC/MS/MS data bank for 464 pesticides. On the basis of this study, a new method for quantitative determination of 587 pesticide residues in animal muscles such as beef, mutton, pork, chicken, and rabbit has been established using GPC cleanup followed by GC/MS and LC/MS/MS. In the method, 10 g animal samples were mixed with 20 g sodium sulfate and extracted twice with 35 mL cyclohexaneethyl acetate (1 + 1) by blender homogenization followed by centrifugation, filtration, and concentration. An equivalent of 5 g sample was injected into a 400 25 mm S-X3 GPC column, with cyclohexaneethyl acetate (1 + 1) as the mobile phase at a flow rate of 5 mL/min. The 2240 min fraction was collected for subsequent analysis. For the 478 pesticides determined by GC/MS, the portions collected from GPC were concentrated to 0.5 mL and exchanged twice with 5 mL hexane. For the 379 pesticides determined by LC/MS/MS, the portions collected from GPC were dissolved with acetonitrilewater (60 + 40) after taking the extract to dryness with nitrogen gas. At the limit of quantification (LOQ) and 10 LOQ fortification levels of 0.116 000 g/kg, recoveries were within 40130, among which 563 pesticide recoveries were between 60 and 130, accounting for 96 of the compounds; 24 analytes were recovered between 40 and 60, accounting for 4 of the compounds. The relative standard deviation was below 30 for all 587 pesticides. The limits of detection for the method were 0.11600 g/kg. In comparison with GC/MS, LC/MS/MS increased the detection sensitivity 21000 times for 236 pesticides.

High-Throughput GC/MS and HPLC/MS/MS Techniques for the Multiclass, Multiresidue Determination of 653 Pesticides and Chemical Pollutants in Tea

An effcient and sensitive method has been established for simultaneous determination of 653 pesticides in teas by GC/MS and HPLC/MS/MS. The method involved extraction with acetonitrile followed by cleanup using Cleanert-TPT SPE and subsequent identifcation and quantitation of 490 pesticides by GC/MS and 448 pesticides by HPLC/MS/MS. The LODs for pesticides determined by GC/MS were between 1.0 and 500 µg/kg, and those determined by HPLC/MS/MS were between 0.03 and 4820 µg/kg. At the low fortifcation levels of 0.01–100 µg/kg, the average recoveries of 94% of the pesticides determined by GC/MS were between 60 and 120%, 77% of which had an RSD below 20%. For 91% of pesticides determined by HPLC/MS/MS, the average recoveries were between 60 and 120%, 76% of which had an RSD below 20%. The paper also reports a novel SPE column, Cleanert TPT, which comprised graphitized carbon black (PestiCarb), polyamine silica, and amide polystyrene for purifying the tea samples. The results indicated good repeatiblity and reproducibility.

Simultaneous Determination of 16 Sulfonamides in Honey by Liquid Chromatography/TandemMass Spectrometry

A method is described for the determination of 16 sulfonamides in honey. Samples are dissolved in phosphoric acid solution (pH2), cleaned up with 2 solid-phase extraction (SPE) cartridges, an aromatic sulfonic cation-exchange cartridge and an Oasis HLB SPE cartridge, and analyzed both qualitatively and quantitatively by liquid chromatography/tandem mass spectrometry (LC/MS/MS) under the selected conditions. Without exception, calibration curves were linear (r = &gt;0.995), when sulfamethizole was between 1.0 and 25.0 μg/kg; sulfacetamide, sulfapyridine, sulfadiazine, sulfachloropyridazine, sulfamethoxazole, sulfamerazine, sulfisoxazole, sulfamonomethoxine, and sulfadoxine were between 2.0 and 50.0 μg/kg; sulfamethoxypyridazine, sulfadimethoxine, and sulfathiazole were between 4.0 and 100.0 μg/kg; sulfamethazine and sulfameter were between 8.0 and 200.0 μg/kg; and sulfaphenazole was between 12.0 and 300.0 μg/kg. Average recoveries at 4 fortification levels in the range of 1.0–300 μg/kg in honey were 70.9–102.5%, and relative standard deviations were 2.02–11.52%. The limits of quantitation for the 16 sulfonamides were between 1.0 and 12.0 μg/kg, with the LC/MS/MS method.

Evaluation of Analyte Stability and Method Ruggedness in the Determination of Streptomycin Residues in Honey by Liquid Chromatography with Post-Column Derivatization

This study demonstrated that streptomycin in honey is quite stable, and the results showed no obvious differences for 3 samples containing incurred analyte during continuous testing for 4 months. Fifteen laboratories evaluated method performance at 4 fortification levels ranging from 0.010 to 0.100 mg/kg; the recoveries ranged from 73.7 to 78.5%, the reproducibility relative standard deviations ranged from 5.76 to 15.85%, and the repeatability relative standard deviations ranged from 1.64 to 3.80%. In 1999–2002, the method was used to determine streptomycin residues in 5106 lots of honey samples from &gt;20 provinces all over China. All of the honey samples were found to be in conformity with the requirements of customs clearance for exports to Europe, the United States, and Japan. The continuous 4-year quality analysis also found that C18 solid-phase extraction cartridges should be standardized to ensure that the analytical results are accurate when different lots of cartridges are used.

Determination of Clopidol Residues in Chicken Tissues by Liquid Chromatography: Collaborative Study

Eighteen laboratories participated in a collaborative study on the determination of clopidol residues in chicken muscle tissues by liquid chromatography. Of these, results from 16 laboratories which rigorously followed the method were subjected to statistical analysis. The method performance was assessed by all participants using 14 samples of chicken muscle fortified at concentrations ranging from 0.1 to 5.0 mg/kg. In addition, 9 participants each reported results for 6 clopidol-incurred samples in chicken muscle. Test portions were extracted with acetonitrile, and the extracts were purified with alumina and anion exchange resin solid-phase extraction cartridges in sequence. Clopidol was separated by reversed-phase liquid chromatography and quantified at 270 nm. Average recoveries ranged from 81.8 to 85.4%, reproducibility relative standard deviation (RSDR) ranged from 11.9 to 22.6%, and repeatability relative standard deviation (RSDr) ranged from 9.9 to 15.1%. For clopidol-incurred samples at concentrations of 0.100–0.687 mg/kg, the mean determination value range was 0.099–0.659 mg/kg; RSDR was 12.6–19.8%, RSDr was 3.1–8.5%; and HORRAT values were 0.7–1.1. The accuracy and precision of the method are in conformity with the requirements specified by AOAC INTERNATIONAL. The method was adopted Official First Action in April 2003.

Determination of Clopidol Residues in Chicken Tissues by Liquid Chromatography: Part I. Optimization of Analytical Conditions and Comparison with AOAC Gas Chromatography Method

A simple and specific liquid chromatographic method was developed for determination of clopidol in chicken tissues. Samples were extracted with acetonitrile. The extracts were cleaned up on an alumina column and an anion exchange column. The clopidol was separated on a column (30 cm × 3.9 mm) of μBondapak C18 (10 μm) by using acetonitrile–water (20 + 80, v/v) as mobile phase, and determined quantitatively at 270 nm. Recoveries were 86.0–97.6%, with relative standard deviations of 2.14–9.42% at 0.010–2.0 mg/kg from 4 spiked matrixes of chicken muscle, egg, liver, and kidney. The limit of detection was 0.005 mg/kg. Compared with the modified AOAC gas chromatographic method, the present method is simple and fast to operate. Its results are accurate and reliable, making it favorable for environmental protection and meeting requirements for human safety. Thus, it is suitable for routine analysis of large quantities of samples.

Determination of Clopidol Residues in Chicken Tissues by Liquid Chromatography: Part III. Quality Control Analysis of Export Chickens

A summary is presented of the liquid chromatographic (LC) determination of clopidol residues in export chickens from 1992 to 1999. Over the past 8 years, we analyzed &gt;7000 chicken samples. A total of 0.66% of samples contained clopidol residues, ranging from 0.005 to 0.79 mg/kg; however, none exceeded 3 mg/kg, the Chinese maximum residue limit. In comparison with 1992, the number of samples multiplied 70-fold, and the frequency of clopidol found in samples decreased 148-fold in 1999. The chickens inspected were exported to foreign countries; all were cleared by the buyers with no disputes. This report also introduces the critical control points of the proposed LC method as well as identification of false-positive procedures by both experience and LC/mass spectrometric confirmation. Our experiences over the past 8 years have demonstrated that the ruggedness of the proposed LC method is quite good.

Organophosphorus pesticide triazophos: A new endocrine disruptor chemical of hypothalamus-pituitary-adrenal axis

The organophosphorus pesticide, triazophos (TAP) was banned to use in agriculture in several countries due to its high toxicity. However, TAP was still widely used and frequently detected in foods. Recently, many studies reported the endocrine-disrupting effect of pesticides, especially the hypothalamic-pituitary-thyroid and hypothalamic-pituitary-gonadal axis. In this study, adult male Wistar rats were exposed to TAP at the dose of 0.164 and 1.64 mg/kg bodyweight (~1/500th and 1/50th of LD₅₀) for 24 weeks and serum contents of hormones were measured. TAP exposure significantly reduced serum contents of adrenocorticotropic hormone, corticosterone and epinephrine in rats (p < .05), leading to the delay in glucose homeostasis during the insulin tolerance test and decrease in serum contents of total cholesterol, triglyceride and low density lipoprotein. Molecular docking results suggested TAP may be an antagonist of glucocorticoid receptor which decreased significantly in the liver of rats, resulting in the decreased expression of 11β-hydroxysteroid dehydrogenase 1 and PEPCK1. This study revealed that TAP is a potential endocrine disruptor, especially in the hypothalamus-pituitary-adrenal system and may disturb the metabolism by affecting glucocorticoid receptor. This study provided new evidence about the toxicity of TAP and it was necessary to strictly control the usage of TAP in food.

Age- and diet-specific effects of chronic exposure to chlorpyrifos on hormones, inflammation and gut microbiota in rats

Chlorpyrifos is a pesticide frequently detected in food and has been reported to disturb endocrine and gut health, which was regulated by gut microbiota and enteroendocrine cells. In this study, newly weaned (3 week) and adult (8 week) male rats fed a normal- or high- fat diet were chronically exposed to 0.3 mg chlorpyrifos/kg bodyweight/day. The effects of chlorpyrifos exposure on serum hormone levels, proinflammatory cytokines and gut microbiota were evaluated. Chronic exposure to chlorpyrifos significantly decreased the concentrations of luteinizing hormone, follicule stimulating hormone and testosterone, which was found only in the normal-fat diet. The counteracted effect of high-fat diet was also found in gut hormones and proinflammatory cytokines. Significantly higher concentrations of glucagon-like peptide-1, pancreatic polypeptide, peptide tyrosine tyrosine (PYY), ghrelin, gastric inhibitory poly-peptide, IL-6, monocyte chemoattractant protein-1, and TNF-α were found in rats exposed to chlorpyrifos beginning at newly weaned, whereas only the PYY, ghrelin and IL-6 concentrations increased significantly in rats exposed in adulthood. Furthermore, a decrease in epinephrine induced by chlorpyrifos exposure was found in rats exposed to chlorpyrifos beginning at newly weaned, regardless of their diet. Chlorpyrifos-induced disturbances in the microbiome community structure were more apparent in rats fed a high-fat diet and exposed beginning at newly weaned. The affected bacteria included short-chain fatty acid-producing bacteria (Romboutsia, Turicibacter, Clostridium sensu stricto 1, norank_f_Coriobacteriaceae, Faecalibaculum, Parasutterella and norank_f__Erysipelotrichaceae), testosterone-related genus (Turicibacter, Brevibacterium), pathogenic bacteria (Streptococcus), and inflammation-related bacteria (unclassified_f__Ruminococcaceae, Ruminococcaceae_UCG-009, Parasutterella, Oscillibacter), which regulated the endocrine system via the hypothalamic-pituitary-adrenal axis, as well as the immune response and gut barrier. Early exposure accelerated the endocrine-disturbing effect and immune responses of chlorpyrifos, although these effects can be eased or recovered by a high-fat diet. This study helped clarify the relationship between disrupted endocrine function and gut microbiota dysbiosis induced by food contaminants such as pesticides.

Assessment of the endocrine-disrupting effects of organophosphorus pesticide triazophos and its metabolites on endocrine hormones biosynthesis, transport and receptor binding in silico

Triazophos (TAP) was a widely used organophosphorus insecticide in developing countries. TAP could produce specific metabolites triazophos-oxon (TAPO) and 1-phenyl-3-hydroxy-1,2,4-triazole (PHT) and non-specific metabolites diethylthiophosphate (DETP) and diethylphosphate (DEP). The objective of this study involved computational approaches to discover potential mechanisms of molecular interaction of TAP and its major metabolites with endocrine hormone-related proteins using molecular docking in silico. We found that TAP, TAPO and DEP showed high binding affinity with more proteins and enzymes than PHT and DETP. TAP might interfere with the endocrine function of the adrenal gland, and TAP might also bind strongly with glucocorticoid receptors and thyroid hormone receptors. TAPO might disrupt the normal binding of androgen receptor, estrogen receptor, progesterone receptor and adrenergic receptor to their natural hormone ligands. DEP might affect biosynthesis of steroid hormones and thyroid hormones. Meanwhile, DEP might disrupt the binding and transport of thyroid hormones in the blood and the normal binding of thyroid hormones to their receptors. These results suggested that TAP and DEP might have endocrine disrupting activities and were potential endocrine disrupting chemicals. Our results provided further reference for the comprehensive evaluation of toxicity of organophosphorus chemicals and their metabolites.

3-Monochloropropane-1, 2-diol causes irreversible damage to reproductive ability independent of hormone changes in adult male rats

3-MCPD, a contaminant frequently detected in foodstuffs, has been reported to damage human kidneys and testes. Previous studies can be used to evaluate the risk to humans of exposure to excessive 3-MCPD for a short period. However, the effects of withdrawal after 3-MCPD exposure have rarely been studied. Adult male SD rats were orally administered 0, 36 and 72 mg 3-MCPD/kg b.w./day for 4 weeks, followed by a 7-week recovery period. 3-MCPD significantly reduced RBC, HGB and HCT levels, indicating a phenotype of anemia, which returned to normal after the recovery period. 3-MCPD induced dysfunction in the liver and kidneys, which were characterized by hepatomegaly and elevated serum ALT, TBIL levels, and nephromegaly and elevated serum urea, UA contents. These effects were also restored to normal after the recovery period. Although the abnormal levels of testosterone and progesterone returned to normal, 3-MCPD-induced atrophy in testes, decreased sperm concentration and motility, and an increased rate of teratosperm still existed after the recovery period. 3-MCPD can induce restorable anemia and dysfunction in liver and kidney but irreversibly damage the reproductive system with normal sex hormone levels. This study may provide a novel perspective for characterizing the ongoing risk of exposure to 3-MCPD.

High-Throughput Analytical Techniques for the Determination of the Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea, Part VII: A GC-MS, GC-MS/MS, and LC-MS/MS Study of the Degradation Profiles of Pesticide Residues in Green Tea

GC-MS, GC-tandem MS (MS/MS), and LC-MS/MS were used to mathematically define the degradation profiles of pesticide residues in two field trials. Nineteen pesticides were studied in the first field trial and 11 in the second. The results of the field trials demonstrated that the degradation profiles of pesticide residues in green tea can be described with power functions to successfully estimate the amount of time, following pesticide application, pesticide residues appearing in tea in concentrations at and/or above the maximum residue limit (MRL) decrease to concentrations below the MRL. Stability tests on green tea samples stored at room temperature were conducted to determine whether pesticide-incurred green tea samples prepared according to the method used in the field trials would be suitable for the preparation of reference standards for laboratory-proficiency testing trials. This paper reports the results of a GC-MS, GC-MS/MS, and LC-MS/MS study, as well as the suitability of the samples prepared under these conditions for use as pesticide reference standards in tea analysis.

High-Throughput Analytical Techniques for Determination of Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea, Part VI: Study of the Degradation of 271 Pesticide Residues in Aged Oolong Tea by Gas Chromatography-Tandem Mass Spectrometry and Its Application in Predicting the Residue Concentrations of Target Pesticides

The degradation rate of 271 pesticide residues in aged Oolong tea at two spray concentrations, named a and b (a < b), were monitored for 120 days using GC-tandem MS (GC-MS/MS). To research the degradation trends and establish regression equations, determination days were plotted as horizontal ordinates and the residue concentrations of pesticide were plotted as vertical ordinates. Here, we consider the degradation equations of 271 pesticides over 40 and 120 days, summarize the degradation rates in six aspects (A-F), and discuss the degradation trends of the 271 pesticides in aged Oolong tea in detail. The results indicate that >70% of the determined pesticides coincide with the degradation regularity of trends A, B, and E, i.e., the concentration of pesticide will decrease within 4 months. Next, 20 representative pesticides were selected for further study at higher spray concentrations, named c and d (d > c > b > a), in aged Oolong tea over another 90 days. The determination days were plotted on the x-axis, and the differences between each determined result and first-time-determined value of target pesticides were plotted on the y-axis. The logarithmic function was obtained by fitting the 90-day determination results, allowing the degradation value of a target pesticide on a specific day to be calculated. These logarithmic functions at d concentration were applied to predict the residue concentrations of pesticides at c concentration. Results revealed that 70% of the 20 pesticides had the lower deviation ratios of predicted and measured results.

High Throughput Analytical Techniques for the Determination and Confirmation of Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea by GC/MS, GC/MS/MS, and LC/MS/MS: Collaborative Study, First Action 2014.09

Thirty laboratories from fom North and South America, Europe, and Asia participated in this AOAC collaborative study (15 from China; five from Germany; two each from Italy and the United States; and one each from the Republic of Korea, Canada, Spain, Japan, Belgium, and India). Participants represented government regulatory, commercial testing, university, research institute, and private laboratories. The single-laboratory validated (SLV) tea method was evaluated in the collaborative study to determine the recovery and reproducibility of the method under multilaboratory conditions. Since there were no restrictions regarding the type of analytical instrumentation to use for the analyses, laboratories used a combination of equipment that included GC/MS, GC/MS/MS, and LC/MS/MS instruments from 22 different manufacturers, 21 brands of GC and LC columns, 13 different GC temperature programming profiles, 11 LC gradient elution programs, and six different vendor manufactured SPE cartridges. Even though all the analytical performance parameters for all the 653 compounds had been determined in the SLV study, guidance was obtained from an expert review panel of the AOAC Method-Centric Committee on Pesticide Residues to conduct the multilaboratory collaborative study based on 20 selected compounds that can be analyzed by GC/MS and 20 compounds that can be analyzed by LC/MS/MS. Altogether, 560 samples covering the 40 selected pesticides were analyzed in the study. These samples included green tea and oolong tea samples fortified typically at the European Union maximum residue limit for regulatory guidance and compliance, aged tea samples incurred with 20 pesticides, and green tea and oolong tea samples incurred with five pesticides. The analysis of the 560 samples generated a total of 82 459 test results by the 30 participating laboratories. One laboratory failed to meet the proficiency requirements in the precollaborative study. Therefore, its data submitted for the collaborative study were excluded from further analysis and interpretation. The results presented are therefore the 6638 analytical results obtained from the 29 remaining laboratories, which included 1977 results generated by GC/MS, 1704 results by GC/MS/MS, and 2957 results by LC/MS/MS. It was determined after application of the Grubbs and Dixon tests for outliers to the data sets that there were 65 outlier results from the 1977 GC/MS results (3.3%), 65 outlier results from the 1704 GC/MS/MS results (3.8%), and 57 outlier results out of 2957 LC/MS/MS results (1.9%), representing 0.98, 0.98, and 0.86%, respectively, of the 6638 results generated in the study. Analysis with the AOAC statistical software package also confirmed that the method is rugged, and average recovery, average concentration, RSDr, RSDR, and HorRat values all meet recovery and reproducibility criteria for use in multiple laboratories. The Study Director is recommending this method for adoption as an AOAC First Action Official MethodSM.

COMT Val158Met polymorphism is associated with blood pressure and lipid levels in general families of Bama longevous area in China

To see the possible relationship between COMT Val158Met polymorphism and blood pressure (BP) and serum lipid levels and its putative role in human longevity, we genotyped COMT Val158Met (rs4680) by PCR-RFLP for members from Bama long-lived families (BLF, n = 1538), Bama non-long-lived families (BNLF, n = 600), Pingguo (a county outside Bama region) long-lived families (PLF, n = 538) and Pingguo non-long-lived families (PNLF, n = 403) after anthropometric measures were collected and serum lipid levels were detected. The distribution of genotypes and alleles among four family groups was significantly different (all P < 0.01), with GA/AA genotype and minor allele A presenting more frequently in Bama population than Pingguo Population (P < 0.01). The systolic blood pressure (SBP), pulse pressure (PP), total cholesterol (TC), triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C) levels of GG genotype carriers were dramatically higher than non-GG carriers in BNLF (P < 0.05); the SBP and PP levels of GG carriers were lower (P < 0.05) while TC, LDL-C level were higher (P < 0.01) than that of non-GG carriers in PLF; no difference in blood pressure and lipids were observed between genotypes in BLF and PNLF (P > 0.05). Correlation analyses revealed that COMT Val158Met was mainly correlated negatively with SBP, diastolic blood pressure (DBP) and LDL-C in BNLF and negatively with TC level in BLF, BNLF and PLF. These data suggest that COMT Val158Met polymorphism may have more impact on the modulation of BP and lipid profiles in the average families than in the long-lived families in Bama region. The association between this SNP and other phenotypes (e.g. cognition) and its roles in the longevity in Bama area thus warrant further investigation.

High-Throughput Analytical Techniques for Determination of Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea--Part V: A Comparative Study of the Influence of Tea Hydration on the Efficiency of Pesticide Multiresidue Determination Using Three Sample Preparation Methods and GC/MS/MS

This paper describes a comparative study of the influence of three sample preparation techniques (M1: hydration+oscillating extraction+partial extraction solution hexane partitioning cleanup; M2: hydration+oscillating extraction+overall extraction solution SPE cleanup; and M3: pure acetonitrile homogeneous extraction+overall extraction SPE cleanup) on the determination efficiency of 456 pesticide multiresidues in tea. First, it was discovered from the mathematical correlation equation of 329 pesticide recoveries established and log Kow values that the extraction efficiency of hydration method M1 has obvious correlation with pesticide log Kow, making the extraction efficiency of M1 take the shape of an arc trend line with a certain arc hanging down from both ends of polar pesticides and nonpolar pesticides. Second, regarding the M1 method, the interfering matter after co-extraction increased in large quantities, which markedly lowered the S/N of the target pesticides and method sensitivity, leading to an obvious decrease of the method efficiency. The fortification experiment of the uniform limit 0.010 mg/kg proved that with the M1 hydration method there are 23 pesticides with recoveries between 70 and 120% and RSD<20%, accounting for only 5.0%, while with nonhydration method M3 there are 229 pesticides, making up 50%.

High-Throughput Analytical Techniques for Multiresidue, Multiclass Determination of 653 Pesticides and Chemical Pollutants in Tea-Part IV: Evaluation of the Ruggedness of the Method, Error Analysis, and Key Control Points of the Method

A 3 month study was conducted on the ruggedness of a multiresidue method for accuracy and stability. The results indicate that in terms of Youden pair ratios of 201 pesticide aged tea samples falling approximately within 1.00-1.20 of the ratio of theoretical spraying concentrations, the differences do not exceed 5% for percentages made up by ratios of the fixed values obtained by two kinds of instruments for two teas and those made up by 18 circular determinations. However, regarding two kinds of SPE cartridges, the Cleanert TPT cartridge is higher than the ENVI-CARB+primary secondary amine (PSA) cartridge by 10%. Pertaining to RSD values of "parallel samples" and whether it is green tea or Woolong tea, the percentages of RSD≤15% values of the parallel samples all exceed 88%. Whether it is the first or circular determination for two teas and analytical results from two kinds of instruments, the percentages of RSD≤15% values have a difference of less than 6%, while the TPT cartridge is better than ENVI-CARB+PSA by above 6% for the two cartridges. Concerning RSDs of Youden pair ratios, RSD≤15% values have a proportion exceeding 85% for both green tea and Woolong tea, and the percentage is greater than 87% whether it is for two kinds of SPE cartridges or two kinds of instruments. In terms of Youden pair ratios and the classified statistical analysis of the ruggedness data of parallel samples, the proportion of RSD≤15% values of Youden pair ratios is 8% higher for the TPT cartridge than the ENVI-CARB+PSA cartridge; the proportion of RSD≤15% values of parallel samples is 6.2% higher for the TPT cartridge than the ENVI-CARB+PSA cartridge. Data show no marked differences for two teas and two kinds of instruments. A comparison of the aforementioned aspects finds that good ruggedness was obtained with both SPE cleanup methods, and the results from the TPT cartridge are better than those from the ENVI-CARB+PSA cartridge.

PPARD +294C overrepresentation in general and long-lived population in China Bama longevity area and unique relationships between PPARD +294T/C polymorphism and serum lipid profiles

Background

The +294T/C polymorphism in the peroxisome proliferator-activated receptor delta (PPARD) gene is associated with hyperlipidemia in several younger populations, but results are still inconsistence across ethnic groups and its possible impact on the lipid profiles of long-lived individuals remains unexploited. Here, we aimed to evaluate the possible correlation between PPARD +294T/C and serum lipid levels in a long-lived population in Bama, a region known for longevity situated in Guangxi, China.

Methods

Genotyping of PPARD +294T/C polymorphism was conducted in 505 long-lived inhabitants (aged 90 and above, long-lived group, LG) and 468 healthy controls (aged 60–75, non-long-lived group, non-LG) recruited from Bama area.

Results

No difference in allelic and genotypic frequencies was found between the two groups (P > 0.05). However, C-allele and C-genotype (TC and CC) were significantly more frequent in the females of non-LG than were LG after sex stratification. CC carriers exhibited higher LDL-C level in LG (P < 0.05) but lower TC, TG and LDL-C in non-LG (P < 0.05 for each) than TT carriers; C allele carriers (TC/CC) in LG exhibited higher TC, TG, and LDL-C levels as compared with the same genotype and the same lipid parameter in non-LG (P < 0.05 for each). LDL-C in LG was correlated with genotypes while TC, TG, and LDL-C in non-LG were correlated with genotypes (P < 0.05-0.001).

Conclusion

Our results suggest that there were different impact patterns of PPARD +294T/C polymorphism on lipid profiles between long-lived cohort and average population in Bama area and this may be one of the genetic bases of its longevity.

Determination of trace elements in rape honey and its corresponding rape flower and stem by ICP-MS

The determination of 10 trace elements including Na, Mg, P, K, Ca, Mn, Zn, Rb, Sr and Ba, in rape honey and its corresponding rape flower and stem gathered from nine sampling sites was carried out by inductively coupled plasma mass spectrometry (ICP-MS). The contents of K, P, Ca, Mg and Na were obviously higher than Zn, Rb, Mn, Sr and Ba in rape honey, rape flower and rape stem. For the first five elements, K had the highest content, followed by P, Ca, Mg and Na. However, the order of content for latter five elements was not the same in different matrixes. The contents of K, P and Ca were all higher than 1 000 mg x kg(-1) in rape flower and rape stem, while the contents of P, Ca, Mn, Zn and Rb in rape flower were slightly higher than in rape stem. It can be concluded that rape flower showed slightly higher concentrating ability for trace elements than rape stem. Based on these results, radar chart was firstly applied to research the relationship of 10 elements in rape honey and its corresponding rape flower and stem. The aim of the present work was to study the possibility of using trace elements contents in rape flower to trace the geographical and botanical origin of honey instead of rape honey. It can be found from the radar charts that the stars of rape honey, rape flower and rape stem were similar to each other. This research not only provides the basic data of trace elements in comparative study of rape honey, but also gives scientific basis for tracing the origin of rape honey according to the trace elements in corresponding rape flower that replaces those of rape honey.

Cholesteryl ester transfer protein TaqIB polymorphism and its association with serum lipid levels and longevity in Chinese Bama Zhuang population

Background

TaqIB polymorphism in the cholesteryl ester transfer protein (CETP) gene has been reported to be associated with serum high-density lipoprotein cholesterol (HDL-C) levels and longevity in several populations, but controversial results also arose probably due to racial/ethnic diversity. Bama is a remote and mountainous county located in the northwest of Guangxi, People's Republic of China, which has been well known for its longevity for centuries. The current study was to investigate the possible association of CETP TaqIB polymorphism with serum lipid levels and longevity in the Bama Zhuang population.

Methods

The CETP TaqIB genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism in 523 long-lived inhabitants (long-lived group, LG; aged 90-107 years) and 498 healthy controls without longevity family history (non-long-lived group, non-LG; aged 40-69 years) residing in Bama County.

Results

The levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were higher but TG, HDL-C/LDL-C ratio and the prevalence of dyslipidemia were lower in LG than in non-LG (P < 0.001 for all). There were no differences in the allelic and genotypic frequencies between the two groups (P > 0.05). Serum HDL-C levels and HDL-C/LDL-C ratio in LG were different among the genotypes (P < 0.01 for each), the subjects with B2B2 and B1B2 genotyes had higher HDL-C levels and HDL-C/LDL-C ratio than the subjects with B1B1genotye, whereas the levels of TC and HDL-C in non-LG were different among/between the genotypes (P < 0.01 for each), the B2 allele carriers had lower TC and higher HDL-C levels than the B2 allele noncarriers. Serum TG and HDL-C levels and HDL-C/LDL-C ratio were correlated with genotypes in LG, whereas serum TC and HDL-C levels were associated with genotypes in non-LG (P < 0.05-0.001).

Conclusions

The association of CETP TaqIB polymorphism and serum lipid profiles is different between LG and non-LG in the Chinese Bama Zhuang population. CETP TaqIB polymorphism might be one of the longevity-related genetic factors in this population.

High-throughput GC/MS and HPLC/MS/MS techniques for the multiclass, multiresidue determination of 653 pesticides and chemical pollutants in tea

An efficient and sensitive method has been established for simultaneous determination of 653 pesticides in teas by GC/MS and HPLC/MS/MS. The method involved extraction with acetonitrile followed by cleanup using Cleanert-TPT SPE and subsequent identification and quantitation of 490 pesticides by GC/MS and 448 pesticides by HPLC/MS/ MS. The LODs for pesticides determined by GC/MS were between 1.0 and 500 microg/kg, and those determined by HPLC/MS/MS were between 0.03 and 4820 microg/kg. At the low fortification levels of 0.01-100 microg/kg, the average recoveries of 94% of the pesticides determined by GC/MS were between 60 and 120%, 77% of which had an RSD below 20%. For 91% of pesticides determined by HPLC/MS/MS, the average recoveries were between 60 and 120%, 76% of which had an RSD below 20%. The paper also reports a novel SPE column, Cleanert TPT, which comprised graphitized carbon black (PestiCarb), polyamine silica, and amide polystyrene for purifying the tea samples. The results indicated good repeatiblity and reproducibility.

Simultaneous determination of 346 multiresidue pesticides in grapes by PSA-MSPD and GC-MS-SIM

The article demonstrates a method of simultaneous determination for 352 pesticide residues in grapes using primary-secondary amine (PSA) matrix solid phase dispersion (MSPD) cleanup and gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM). Grape samples (15 g) were mixed with 6 g of anhydrous magnesium sulfate and 1.5 g of sodium chloride, and then extracted with acetonitrile (15 mL) and cleaned up with 0.3 g of dispersive PSA. The analytes were determined by GC-MS-SIM. Four injections for one sample were acquired to cover a total of 352 pesticides. The limit of detection (LOD) for the method was 0.0017-0.2667 mg kg(-1), depending on the nature of compounds. The linear correlation coefficient (r) was equal to or greater than 0.95; at low, medium, and high fortification levels, recoveries ranged from 45% to 136% for 352 pesticides, among which the recoveries between 60%-120% accounted for 97%. The pesticides for which the relative standard deviations (RSD) were equal to or below 20% accounted for 95%. A positive of nine varieties of grape samples was detected out, one of which was abtained Changli city, Hebei province, China. Pesticides were identified by the retention time, molecule ions, fragment ions, and the abundance ratio of the selected ions. The analytical method was rugged, quick, cheap and effective, and suitable for the determination of a wide scope of 346 pesticides in grapes.

Analysis method study on 839 pesticide and chemical contaminant multiresidues in animal muscles by gel permeation chromatography cleanup, GC/MS, and LC/MS/MS

The paper reports the study of gel permeation chromatography (GPC), gas chromatography/mass spectrometry (GS/MS), and column chromatography tandem MS (LC/MS/MS) for 839 pesticides and chemical contaminants, through which a GPC data bank has been established for 744 pesticides, a GC/MS data bank for 541 pesticides, and an LC/MS/MS data bank for 464 pesticides. On the basis of this study, a new method for quantitative determination of 587 pesticide residues in animal muscles such as beef, mutton, pork, chicken, and rabbit has been established using GPC cleanup followed by GC/MS and LC/MS/MS. In the method, 10 g animal samples were mixed with 20 g sodium sulfate and extracted twice with 35 mL cyclohexane-ethyl acetate (1 + 1) by blender homogenization followed by centrifugation, filtration, and concentration. An equivalent of 5 g sample was injected into a 400 x 25 mm S-X3 GPC column, with cyclohexane-ethyl acetate (1 + 1) as the mobile phase at a flow rate of 5 mL/min. The 22-40 min fraction was collected for subsequent analysis. For the 478 pesticides determined by GC/MS, the portions collected from GPC were concentrated to 0.5 mL and exchanged twice with 5 mL hexane. For the 379 pesticides determined by LC/MS/MS, the portions collected from GPC were dissolved with acetonitrile-water (60 + 40) after taking the extract to dryness with nitrogen gas. At the limit of quantification (LOQ) and 10 LOQ fortification levels of 0.1-16 000 microg/kg, recoveries were within 40-130%, among which 563 pesticide recoveries were between 60 and 130%, accounting for 96% of the compounds; 24 analytes were recovered between 40 and 60%, accounting for 4% of the compounds. The relative standard deviation was below 30% for all 587 pesticides. The limits of detection for the method were 0.1-1600 microg/kg. In comparison with GC/MS, LC/MS/MS increased the detection sensitivity 2-1000 times for 236 pesticides.

Validation study on 660 pesticide residues in animal tissues by gel permeation chromatography cleanup/gas chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry

A new method using gel permeation chromatography (GPC) cleanup followed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) has been established for quantitative determination of 437 pesticide residues in animal tissues such as beef, mutton, pork, chicken, and rabbit. Based on an appraisal of the characteristics of both GC-MS and LC-MS-MS, validation experiments were conducted for 660 pesticides. In the method, 10 g animal samples were mixed with 20 g sodium sulfate and extracted with 35 mL of cyclohexane+ethyl acetate (1+1) twice by blender homogenization, centrifugation, and filtration. Evaporation was conducted and an equivalent of 5 g sample was injected into a 400 mm x 25 mm S-X3 GPC column, with cyclohexane+ethyl acetate (1+1) as the mobile phase at a flow rate of 5 mL/min. The 22-40 min fraction was collected for subsequent analysis. For the 368 pesticides determined by GC-MS, the portions collected from GPC were concentrated to 0.5 mL and exchanged with 5 mL hexane twice. For the 69 pesticides by LC-MS-MS, the portions collected from GPC were dissolved with acetonitrile+water (60+40) after taking the extract to dryness with nitrogen gas. In the linear range of each pesticide, the correlation coefficient was r > or = 0.98, exceptions being dinobuton, linuron, and fenamiphos sulfoxide. At the low, medium and high three fortification levels of 0.2-4800 microg/kg, recoveries fell within 40-120%, among which 417 pesticides recoveries between 60% and 120%, accounting for 95%, 20 analytes between 40% and 60%, accounting for 5%. The relative standard deviation was below 28% for all 437 pesticides. The limits of detection for the method were 0.2-600 microg/kg, depending on each pesticide.

Determination of residues of 446 pesticides in fruits and vegetables by three-cartridge solid-phase extraction-gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry

A method was developed for determination of residues of 446 pesticides in fruits and vegetables through the use of cleanup by a 3-cartridge solid-phase extraction-gas chromatography/ mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Fruit and vegetable samples (20 g) were extracted with 40 mL acetonitrile, salted out, and centrifuged. Half of the supernatant was passed into an Envi-18 cartridge, eluted with acetonitrile, and cleaned up with Envi-Carb and aminopropyl Sep-Pak cartridges in series after concentration of the eluates. Pesticides were eluted with acetonitrile-toluene (3 + 1, v/v), and eluates were concentrated to 0.5 mL and then added into internal standards after solvent exchange with 2 mL hexane and used for determination of 383 pesticides by GC/MS. The other half of the supernatant was concentrated to 1 mL and cleaned up with Envi-Carb and aminopropyl Sep-Pak cartridges in series. Pesticides were eluted with acetonitrile-toluene (3 + 1, v/v), and the eluates were concentrated to 0.5 mL, dried with nitrogen gas, diluted to 1.0 mL with acetonitrile-water (3 + 2, v/v), and used for determination of 63 pesticides by LC/MS/MS. The limit of detection for the method was 0.2-600 ng/g depending on the individual pesticide. In the method, fortification recovery tests at high, medium, and low levels were conducted on 6 varieties of fruits and vegetables, i.e., apples, oranges, grapes, cabbage, tomatoes, and celery, with average recoveries falling within the range of 55.0-133.8% for 446 pesticides, among which average recoveries between 60.0-120.0% accounted for 99% of the results. The relative standard deviation was between 2.1-39.1%, of which a relative standard deviation of 2.1-25.0% made up 96% of the results. Experiments proved that the method was applicable for determination of residues of 446 pesticides in fruit and vegetables.

Simultaneous determination of 405 pesticide residues in grain by accelerated solvent extraction then gas chromatography-mass spectrometry or liquid chromatography-tandem mass spectrometry

A new method has been established for simultaneous determination of 405 pesticide residues in grain, using accelerated solvent extraction (ASE), solid-phase extraction (SPE), and GC-MS and LC-MS-MS. The method was based on appraisal of the GC-MS and LC-MS-MS characteristics of 660 pesticides, their efficiency of extraction from grain, and their purification. Samples of grain (10 g) were mixed with Celite 545 (10 g) and the mixture was placed in a 34-mL cell of an accelerated solvent extractor and extracted with acetonitrile in the static state for 3 min with two cycles at 1,500 psig and at 80 degrees C. For the 362 pesticides determined by GC-MS, half of the extracts were cleaned with an Envi-18 cartridge and then further cleaned with Envi-Carb and Sep-Pak NH2 cartridges in series. The pesticides were eluted with acetonitrile-toluene, 3:1, and the eluates were concentrated and used for analysis after being exchanged with hexane twice. For the 43 pesticides determined by LC-MS-MS the other half of the extracts were cleaned with Sep-Pak Alumina N cartridge and further cleaned with Envi-Carb and Sep-Pak NH2 cartridges. Pesticides were eluted with acetonitrile-toluene, 3:1. After evaporation to dryness the eluates were diluted with acetonitrile-water, 3:2, and used for analysis. In the linear range of each pesticide the linear correlation coefficient r was equal to or greater than 0.956 and 94% of linear correlation coefficients were greater than 0.990. At low, medium, and high fortification levels, at the limit of detection (LOD), twice the LOD and ten times LOD, respectively, recoveries ranged from 42 to 132%; for 382 pesticides, or 94.32%, recovery was from 60 to 120%. The relative standard deviation (RSD) was always below 38% and was below 30% for 391 pesticides, or 96.54%. The LOD was 0.0005-0.3000 mg kg(-1). The proposed method is suitable for determination of 405 pesticide residues in grain such as maize, wheat, oat, rice, and barley, etc.

Simultaneous determination of 16 sulfonamides in honey by liquid chromatography/tandem mass spectrometry

A method is described for the determination of 16 sulfonamides in honey. Samples are dissolved in phosphoric acid solution (pH2), cleaned up with 2 solid-phase extraction (SPE) cartridges, an aromatic sulfonic cation-exchange cartridge and an Oasis HLB SPE cartridge, and analyzed both qualitatively and quantitatively by liquid chromatography/tandem mass spectrometry (LC/MS/MS) under the selected conditions. Without exception, calibration curves were linear (r = > 0.995), when sulfamethizole was between 1.0 and 25.0 microg/kg; sulfacetamide, sulfapyridine, sulfadiazine, sulfachloropyridazine, sulfamethoxazole, sulfamerazine, sulfisoxazole, sulfamonomethoxine, and sulfadoxine were between 2.0 and 50.0 microg/kg; sulfamethoxypyridazine, sulfadimethoxine, and sulfathiazole were between 4.0 and 100.0 microg/kg; sulfamethazine and sulfameter were between 8.0 and 200.0 microg/kg; and sulfaphenazole was between 12.0 and 300.0 microg/kg. Average recoveries at 4 fortification levels in the range of 1.0-300 microg/kg in honey were 70.9-102.5%, and relative standard deviations were 2.02-11.52%. The limits of quantitation for the 16 sulfonamides were between 1.0 and 12.0 microg/kg, with the LC/MS/MS method.

Evaluation of analyte stability and method ruggedness in the determination of streptomycin residues in honey by liquid chromatography with post-column derivatization

This study demonstrated that streptomycin in honey is quite stable, and the results showed no obvious differences for 3 samples containing incurred analyte during continuous testing for 4 months. Fifteen laboratories evaluated method performance at 4 fortification levels ranging from 0.010 to 0.100 mg/kg; the recoveries ranged from 73.7 to 78.5%, the reproducibility relative standard deviations ranged from 5.76 to 15.85%, and the repeatability relative standard deviations ranged from 1.64 to 3.80%. In 1999-2002, the method was used to determine streptomycin residues in 5106 lots of honey samples from >20 provinces all over China. All of the honey samples were found to be in conformity with the requirements of customs clearance for exports to Europe, the United States, and Japan. The continuous 4-year quality analysis also found that C18 solid-phase extraction cartridges should be standardized to ensure that the analytical results are accurate when different lots of cartridges are used.

Determination of clopidol residues in chicken tissues by liquid chromatography: collaborative study

Eighteen laboratories participated in a collaborative study on the determination of clopidol residues in chicken muscle tissues by liquid chromatography. Of these, results from 16 laboratories which rigorously followed the method were subjected to statistical analysis. The method performance was assessed by all participants using 14 samples of chicken muscle fortified at concentrations ranging from 0.1 to 5.0 mg/kg. In addition, 9 participants each reported results for 6 clopidol-incurred samples in chicken muscle. Test portions were extracted with acetonitrile, and the extracts were purified with alumina and anion exchange resin solid-phase extraction cartridges in sequence. Clopidol was separated by reversed-phase liquid chromatography and quantified at 270 nm. Average recoveries ranged from 81.8 to 85.4%, reproducibility relative standard deviation (RSDR) ranged from 11.9 to 22.6%, and repeatability relative standard deviation (RSDr) ranged from 9.9 to 15.1%. For clopidol-incurred samples at concentrations of 0.100-0.687 mg/kg, the mean determination value range was 0.099-0.659 mg/kg; RSDR was 12.6-19.8%, RSDr was 3.1-8.5%; and HORRAT values were 0.7-1.1. The accuracy and precision of the method are in conformity with the requirements specified by AOAC INTERNATIONAL. The method was adopted Official First Action in April 2003.

Liquid chromatography-fluorescence detection for simultaneous analysis of sulfonamide residues in honey

A rapid, accurate LC analytical method has been developed for determination of eight sulfonamides (sulfacetamide, sulfapyridine, sulfamerazine, sulfamethoxypyridazine, sulfameter, sulfachloropyridazine, sulfamethoxazole and sulfadimethoxine) in honey. The sample was dissolved in phosphoric acid solution (pH 2). After filtration, the sample solution was cleaned by use of two solid-phase extraction (SPE) cartridges-an aromatic sulfonic cation-exchange cartridge and an Oasis HLB cartridge. The eight sulfonamides were then derivatized with fluorescamine and the derivatives were determined by LC with fluorescence detection at excitation and emission wavelengths of 405 and 495 nm, respectively. Average recoveries at three fortification levels in the range 0.02-0.50 mg kg(-1) in twelve different kinds of honey were 73.5-94.1% with coefficients of variation of 4.35-16.60%. The limit of detection (LOD) was 0.002 mg kg(-1) for sulfacetamide, sulfapyridine, sulfamerazine, and sulfamethoxypyridazine; that for sulfameter, sulfachloropyridazine, sulfamethoxazole and sulfadimethoxine was 0.005 mg kg(-1). The limit of quantitation (LOQ) was 0.005 mg kg(-1) for sulfacetamide, sulfapyridine, sulfamerazine, and sulfamethoxypyridazine; that for sulfameter, sulfachloropyridazine, sulfamethoxazole, and sulfadimethoxine was 0.010 mg kg(-1). The method is suitable for determination of multiresidue sulfonamides in the various kinds of honey.

Determination of clopidol residues in chicken tissues by liquid chromatography: part II. Distribution and depletion of clopidol in chicken tissues

A study was made of the distribution and depletion of clopidol residues at different tissue locations in chickens fed with feeds incurred with clopidol. Experiments showed that the residue levels were not identical at 5 different tissue locations in each chicken. The sequence of residue levels from high to low was livers, kidneys, upper breast, lower breast, and leg meat. The maximum residue values after suspension of the drug for 8 h were (mg/kg): livers, 4.600; kidneys, 3.619; upper breast, 1.742; lower breast, 1.641; leg meat, 1.525. The averages were taken after values for 10 chickens were determined. After suspension of the drug for 3 days, >80% residue clopidol was depleted, and the depletion was nearly completed within 7 days. The speed of depletion varied at different tissue locations in each chicken, with the sequence from fast to slow being equivalent to that of the residue levels. Analytical results of 350 samples during 7 days showed that the proposed method is specific for determination of clopidol in chickens.