Validation and uncertainty study of a comprehensive list of 160 pesticide residues in multi-class vegetables by liquid chromatography–tandem mass spectrometry

2-Methyl-4'-(methylthio)-2-morpholinopropiophenone: A commercial photoinitiator being used as a new psychoactive substance

Synthetic cathinones, which are novel psychoactive substances, have caused major social problems worldwide. A substance called 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MMMP), which is employed as a commercial industrial photoinitiator for triggering polymerization, has a basic cathinone backbone; however, few reports regarding MMMP have been published. In the current study, three potential metabolites of MMMP-namely hydroxy-MMMP (HO-MMMP), HO-MMMP-sulfoxide (HO-MMMP-SO), and HO-MMMP-sulfone (HO-MMMP-SO2)-were successfully synthesized, and MMMP and these three potential metabolites were used as standards to establish an analytic method based on liquid chromatography-tandem mass spectrometry for the quantitative analysis of urine. This analytic method and related parameters-including dynamic range, limit of quantification, selectivity, precision, accuracy, carryover effect, matrix effect, interference, and dilution integrity-were optimized and validated. Forty urine samples from 1,691 individuals who abused drugs were determined to contain MMMP, HO-MMMP, HO-MMMP-SO, or HO-MMMP-SO2; the results of this study indicate that approximately 2.37 % of drug abusers in Taiwan consumed MMMP in 2023. These 40 urine samples were analyzed to investigate the metabolism of MMMP in humans. The results indicate that HO-MMMP-SO is the main metabolite in human urine. This study recommends HO-MMMP-SO with a concentration of 2 ng/mL as a target and cutoff value, respectively, for identifying individuals who have consumed MMMP.

Development of a LC-QTOF-MS based dilute-and-shoot approach for the botanical discrimination of honeys

Honeys of particular botanical origins can be associated with premium market prices, a trait which also makes them susceptible to fraud. Currently available authenticity testing methods for botanical classification of honeys are either time-consuming or only target a few "known" types of markers. Simple and effective methods are therefore needed to monitor and guarantee the authenticity of honey. In this study, a 'dilute-and-shoot' approach using liquid chromatography (LC) coupled to quadrupole time-of-flight-mass spectrometry (QTOF-MS) was applied to the non-targeted fingerprinting of honeys of different floral origin (buckwheat, clover and blueberry). This work investigated for the first time the impact of different instrumental conditions such as the column type, the mobile phase composition, the chromatographic gradient, and the MS fragmentor voltage (in-source collision-induced dissociation) on the botanical classification of honeys as well as the data quality. Results indicated that the data sets obtained for the various LC-QTOF-MS conditions tested were all suitable to discriminate the three honeys of different floral origin regardless of the mathematical model applied (random forest, partial least squares-discriminant analysis, soft independent modelling by class analogy and linear discriminant analysis). The present study investigated different LC-QTOF-MS conditions in a "dilute and shoot" method for honey analysis, in order to establish a relatively fast, simple and reliable analytical method to record the chemical fingerprints of honey. This approach is suitable for marker discovery and will be used for the future development of advanced predictive models for honey botanical origin.

Optimization and validation of high-performance liquid chromatography using modified QuEChERS to determine anthelmintic drugs in mutton

The aim of this study was to rapidly determine the presence of anthelmintic drugs in sheep meat using the optimized high-performance liquid chromatography-ultraviolet (HPLC-UV) method with modified QuEChERS (quick, easy, cheap, effective, rugged, safe) technology. Fifty fresh sheep meat samples from different slaughterhouses were collected. A double extraction procedure (QuEChERS/HPLC-UV technology) was used to extract the target analytes. A multilevel calibration curve from 1 to 1000 g/kg was used to establish instrument linearity for rafoxanide, albendazole, and closantel, whereas 0.1-100 μg/kg was used for ivermectin, levamisole, and oxyclozanide to find the lowest concentration, maximum residue limit (MRL), and occupied range for targeted analytes. The concentration levels were used to investigate the linearity, whereas several certified reference materials were applied to determine accuracy. The process was linear for all combinations, from the limit of quantification (LOQ) to the maximum concentration. The LOQ was established at 0.5 μg/kg for ivermectin, levamisole, and oxyclozanide and 10 μg/kg for rafoxanide, albendazole, and closantel. Recovery values were 70%-120%, and repeatability/reproducibility stated in relative standard deviation was obtained at less than 20%. QuEChERS method revealed that most meat samples contained anthelmintic drug residues, of which the majority exceeded the MRLs. Thus, the drugs should be used correctly in animals to avoid residues in food for human consumption.

A multi-residue method for the analysis of organic pollutants released from atmospheric PM2.5 in simulated biological fluids: Inhalation bioaccessibility and bioavailability estimation

BACKGROUND

In recent decades, there has been a growing interest within the scientific community regarding the study of the fraction that could be released in simulated biological fluids to estimate in vitro bioaccessibility and bioavailability of compounds. Concerning particulate matter (PM), studies were essentially focused on metal (oid)s probably due to more complex methodologies needed for organic compounds, requiring extraction and pre-concentration steps from simulated fluids, followed by chromatographic analysis. Thus, the development of a simple and sensitive methodology for the analysis of multi-class organic compounds released in different inhalation simulated fluids would represent a great contribution to the field.

RESULTS

In this work, a methodology for the analysis of 49 organic pollutants, including 18 polycyclic aromatic hydrocarbons (PAHs), 12 phthalate esters (PAEs), 11 organophosphorus flame retardants (OPFRs), 6 synthetic musk compounds (SMCs) and 2 bisphenols released in simulated fluids from PM2.5 samples was developed. After a physiologically based extraction test (PBET) by using artificial lysosomal fluid (ALF) and a simulated body fluid (SBF, filling a dialysis membrane) to obtain in vitro inhalation bioaccessible and bioavailable fractions, respectively; compounds were determined by a vortex-assisted liquid-liquid extraction (VALLE) and a subsequent analysis by programmed temperature vaporization-gas chromatography-tandem mass spectrometry (PTV-GC-MS/MS). Experimental conditions concerning VALLE extraction (extraction time and amount of NaCl (g)) were optimized by using a central composite design (CCD), best MS/MS transitions were selected and matrix-matched calibration combined with use of labelled subrogate standards provided high sensitivity, minimization of matrix effects and recovering losses compensation.

SIGNIFICANCE

The successful validation results obtained for most of the compounds demonstrated the effectiveness of the proposed methodology for the analysis of multi-class organic pollutants released in ALF and SBF for inhalation bioaccessibility and bioavailability assessment, respectively. Furthermore, applicability of the method was proved by analysing 20 p.m.2.5 samples, being the proposed in vitro PBET dialyzability approach for assessing organic pollutant's inhalation bioavailability applied to PM2.5 samples for the first time.

A Green Bridge: Enhancing a Multi-Pesticide Test for Food by Phase-Transfer Sample Treatment Coupled with LC/MS

The preparation and treatment of the sample has become an important part of the determination process, which directly affects the accuracy of detection. The preparation of the sample for final detection is actually a process of separation and transfer of the target to be tested from the sample matrix. The phase-transfer process of analysis and detection is the process of transferring the target substance to be measured from a complex multiphase system to a simple homogeneous system. This study shows a new phase-transfer process for food sample pretreatment in the determination of carbamate pesticides. Edible gum, xanthan gum, carrageenan, and gelatin were selected for purification testing from the perspective of eco-friendliness and safety. Phase-transfer purification process research was carried out on spinach and other foods. Compared with the commonly used QuEChERS method, the LC/MS results indicate that the straightforward carrageenan treatment process can significantly diminish the detection matrix effect and yield similarly superior detection parameters. The phase-transfer purification method with carrageenan has similar sensitivity and systematic error. The limits of detection and limits of quantitation of each pesticide compound in six plant sample substrates were 0.02-0.36 μg/kg and 0.06-1.9 μg/kg, respectively, which were lower than the residue limits here and abroad. Supplemental recoveries in six blank samples at 5, 20, and 100 μg/kg with the phase-transfer process method were better than those for the QuEChERS method. Positive determination results of actual samples using carrageenan phase-transfer purification proved that this method can be used for related detection from a practical point of view.

Dissipation, Processing Factors and Dietary Exposure Assessment of Myclobutanil in Tomato

Myclobutanil residue poses a potential threat to consumers' health. This work aims to investigate the degradation behavior, residue levels, processing factors (PFs) and dietary risk of myclobutanil in tomato. Myclobutanil was analyzed using a modified quick, easy, cheap, effective, rugged, safe (QuEChERS) method combined with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS), and average recoveries ranged from 82% to 102% with relative standard deviations RSDs ≤ 9.1%. After spraying myclobutanil miscible oil under field conditions, the initial concentration of myclobutanil was 0.055 mg/kg, and its dissipation followed the first-order kinetics equation with a half-life of 2.88 days. Myclobutanil was mainly present in the tomato skin, and its concentration was about four times that in the whole tomato. The initial concentration of myclobutanil in raw tomato was 0.100 mg/kg. After washing, peeling, homogenization, simmering and canning, the residual level of myclobutanil decreased to 0.067 mg/kg, 0.023 mg/kg, 0.013 mg/kg, 0.044 mg/kg and 0.041 mg/kg, respectively. Although the procedure of simmering led to an increase in myclobutanil concentration, the PFs were all less than 1 in the whole process, showing that the processing procedure significantly decreased the residual level of myclobutanil canned tomato paste in comparison with the raw agricultural commodity. Washing, peeling, and homogenization played critical roles in reducing pesticide residues. The residues of myclobutanil during the processing of tomato pose low dietary exposure risks to consumers in China, which were acceptable. However, the acute and chronic risk quotient for children revealed that it was necessary to monitor the dietary exposure of pesticide residues for children closely.

Immunochromatographic test strip for quantitative and rapid detection of tolfenpyrad in food samples

In the study, a hapten was designed to preserve the molecular structure of tolfenpyrad while introducing a carboxyl group and was coupled with a carrier protein to synthesize an immunogen and coating antigen. A monoclonal antibody was fabricated against tolfenpyrad and its performance was assessed by indirect competitive enzyme-linked immunosorbent assay. Finally, we developed a colloidal gold nanoparticle immunochromatographic test strip (CGN-ICTS) for the detection of tolfenpyrad in kale, Chinese cabbage, and eggplant samples. The results shows that CGN-ICTS was sensitive, with calculated detection limits of 0.49 ng/g for kale and Chinese cabbage and 0.99 ng/g for eggplant. Subsequently, CGN-ICTS and LC-MS were used to analyze the tolfenpyrad-spiked samples. The recovery rate of the CGN-ICTS for kale samples was 97.1-103.0%, for Chinese cabbage samples was 93.7-103.4%, and for eggplant samples was 92.7-105.7%. Recovery rates were similar between CGN-ICTS and LC-MS. Therefore, CGN-ICTS can be used to quickly screen tolfenpyrad residues in foods.

Simultaneous analytical method for 296 pesticide multiresidues in root and rhizome based herbal medicines with GC-MS/MS

A method for the simultaneous analysis of pesticide multiresidues in three root/rhizome-based herbal medicines (Cnidium officinale, Rehmannia glutinosa, and Paeonia lactiflora) was developed with GC-MS/MS. To determine the concentrations of pesticide residues, 5 g of dried samples were saturated with distilled water, extracted with 10 mL of 0.1% formic acid in acetonitrile/ethyl acetate (7:3, v/v), and then partitioned using magnesium sulfate and sodium chloride. The organic layer was purified with Oasis PRiME HLB plus light, followed by a cleanup with dispersive solid-phase extraction containing alumina. The sample was then injected into GC-MS/MS (2 μL) using a pulsed injection mode at 15 psi and analyzed using multiple reaction monitoring (MRM) modes. The limit of quantitation for the 296 target pesticides was within 0.002-0.05 mg/kg. Among them, 77.7-88.5% showed recoveries between 70% and 120% with relative standard deviations (RSDs) ≤20% at fortified levels of 0.01, and 0.05 mg/kg. The analytical method was successfully applied to real herbal samples obtained from commercial markets, and 10 pesticides were quantitatively determined from these samples.

Insights into the Uptake, Distribution, and Metabolism of 3-Isobutyl-2-hydroxypyrazine in Grapevine Using a Stable Isotope Tracer

Methoxypyrazines (MPs) are potent aroma compounds that have been predominately studied in grape berries but can also be detected in other vine tissues. The synthesis of MPs in berries from hydroxypyrazines by VvOMT3 is well established, but the origin of MPs in vine tissues that have negligible VvOMT3 gene expression is unknown. This research gap was addressed through the application of stable isotope tracer 3-isobutyl-2-hydroxy-[²H₂]-pyrazine (d₂-IBHP) to the roots of Pinot Meunier L1 microvines and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) quantification of HPs from grapevine tissues following a novel solid-phase extraction method. Four weeks post-application, d₂-IBHP and its O-methylated product 3-isobutyl-2-methoxy-[²H₂]-pyrazine (d₂-IBMP) were present in excised cane, berry, leaf, root, and rachis material. Translocation of d₂-IBHP and d₂-IBMP was investigated, but results were inconclusive. Nonetheless, knowledge that d₂-IBHP, and potentially d₂-IBMP, are translocated from roots to other vine organs, including the berries, could provide opportunities for controlling MP accumulation in grapevine tissues pertinent to winemaking.

Quantification of hetero-cyclic amines from different categories of braised beef by optimized UPLC-TQ-XS/ESI method

This research work has developed and optimized a sensitive analytical method for separation and quantification of heterocyclic amines (HCAs) mainly including PhIP, Harman, Norharman, IQ, MeIQ, AαC, MeAαC and Trp-P-2 by optimizing UPLC-TQ-XS using electrospray ionization source (ESI+) on ACQUITY UPLC® BEH C18 column in <7 min, from braised beef sample matrix. Meanwhile, modified HCAs extraction by modifying QuEChERS (quick, easy, cheap, efficient, rugged and safe) technique and revisited with solid phase extraction (SPE) for HCAs purification, instead using traditional QuEChERS salts. Moreover, optimized pH conditions of HCA extracts before purification, for better extraction recoveries. Furthermore, this method was validated in terms of method validation parameters. Lastly, simulation of real braised beef model provided the minimum formation of HCAs by optimizing cooking parameters and precursors in a cooking system. Therefore, this method could be applied simultaneously on braised beef matrix either marketed or home cooked for HCAs analysis.

LC-MS/MS Method Minimizing Matrix Effect for the Analysis of Bifenthrin and Butachlor in Chinese Chives and Its Application for Residual Study

The matrix effect refers to the change in the analytical signal caused by the matrix in which the sample is contained, as well as the impurities that are co-eluted with the target analyte. In crop sample analysis using LC-MS/MS, the matrix effect can affect the quantification results. Chinese chives are likely to exhibit a strong matrix effect when co-extracted with bifenthrin and butachlor due to the presence of phytochemicals and chlorophyll. A novel analytical method was developed to reduce the matrix effects of bifenthrin and butachlor to a negligible level in Chinese chives. The established method had a limit of quantitation of 0.005 mg/kg and correlation coefficients greater than 0.999 within the range of 0.005-0.5 mg/kg. Matrix effects were found to be negligible, with values ranging from -18.8% to 7.2% in four different sources of chives and two leafy vegetables. Compared to conventional analytical methods for the LOQ and matrix effect, the established method demonstrated improved performances. The analytical method was further applied in a residual study in chive fields. The active ingredient of butachlor 5 granule (GR) was not detected after soil admixture application, while that of bifenthrin 1 emulsifiable concentrate (EC) showed a range from 1.002 to 0.087 mg/kg after foliar spraying. The dissipation rate constant (k) of bifenthrin was determined to be 0.115, thus its half-life was calculated to be 6.0 days. From the results, PHI and safety use standards of both pesticides were suggested. The developed analytical method can be applied to accurately determine bifenthrin and butachlor residues in Chinese chives and provides a foundation for further research on the fate and behavior of these pesticides in the environment.

Characterization of the Polar Profile of Bacon and Fuerte Avocado Fruits by Hydrophilic Interaction Liquid Chromatography-Mass Spectrometry: Distribution of Non-structural Carbohydrates, Quinic Acid, and Chlorogenic Acid between Seed, Mesocarp, and Exocarp at Different Ripening Stages

Avocado fruit growth and development, unlike that of other fruits, is characterized by the accumulation of oil and C7 sugars (in most fruits, the carbohydrates that prevail are C6). There are five essential carbohydrates which constitute 98% of the total content of soluble sugars in this fruit; these are fructose, glucose, sucrose, d-mannoheptulose, and perseitol, which together with quinic acid and chlorogenic acid have been the analytes under study in this work. After applying an efficient extraction procedure, a novel methodology based on hydrophilic interaction liquid chromatography coupled to mass spectrometry was applied to determine the levels of these seven substances in tissues─exocarp, seed, and mesocarp─from avocado fruits of two different varieties scarcely studied, Bacon and Fuerte, at three different ripening stages. Quantitative characterization of the selected tissues was performed, and the inter-tissue distribution of metabolites was described. For both varieties, d-mannoheptulose was the major component in the mesocarp and exocarp, whereas perseitol was predominant in the seed, followed by sucrose and d-mannoheptulose. Sucrose was found to be more abundant in seed tissues, with much lower concentrations in avocado mesocarp and exocarp. Quinic acid showed a predominance in the exocarp, and chlorogenic acid was exclusively determined in exocarp samples.

Improved procedure for square-wave voltammetric sensing of fenhexamid residues on blueberries peel surface at the anodically pretreated boron-doped diamond electrode

BACKGROUND

Fungicide fenhexamid (FH) has a high residual concentration on fruits and vegetables, thus, it is of high importance to monitor the level of FH residues on foodstuff samples. So far, the assay of FH residues in selected foodstuff samples has been conducted by electroanalytical methods on sp² carbon-based electrodes that are well-known to be susceptible to severe fouling of the electrodes surfaces during electrochemical measurements. As an alternative, sp³ carbon-based electrode such as boron-doped diamond (BDD) can be used in the analysis of FH residues retained on the peel surface of foodstuff (blueberries) sample.

RESULTS

In situ anodic pretreatment of the BDDE surface was found to be the most successful strategy to remediate the passivated BDDE surface by FH oxidation (by)products, and the best validation parameters, i.e., the widest linear range (3.0-100.0 μmol L^-1), the highest sensitivity (0.0265 μA L μmol^-1) and the lowest limit of detection (0.821 μmol L^-1), were achieved on the anodically pretreated BDDE (APT-BDDE) in a Britton-Robinson buffer, pH 2.0, using square-wave voltammetry (SWV). The assay of FH residues retained on blueberries peel surface was performed on the APT-BDDE using SWV, and the obtained concentration of FH residues of 6.152 μmol L^-1 (1.859 mg kg^-1) was found to be below the maximum residue value fixed for blueberries by the European Union regulations (20 mg kg^-1).

SIGNIFICANCE AND NOVELTY

In this work, a protocol based on a very easy and fast foodstuff sample preparation procedure combined with the straightforward pretreatment approach of the BDDE surface was elaborated for the first time for the monitoring of the level of FH residues retained on the peel surface of blueberries samples. The presented reliable, cost-effective, and easy-to-use protocol could find its application as a rapid screening method for the control of food safety.

Ultra-sensitive determination of Ochratoxin A in coffee and tea samples using a novel semi-automated in-syringe based coagulant-assisted fast mycotoxin extraction (FaMEx) technique coupled with UHPLC-MS/MS

In this study, we demonstrated a novel semi-automated in-syringe-based coagulant-assisted liquid-liquid microextraction (IS-CGA-LLME) as fast mycotoxin extraction (FaMEx) technique coupled with ultra-high-performance liquid chromatography connected with a tandem-mass spectrometer (UHPLC-MS/MS) for the quantification of mycotoxin (Ochratoxin A, OT-A) in coffee and tea samples. IS-CGA-LLME is a three-step extraction process that includes extraction of OT-A from sample matrix using low-volume solvent extraction, then the extractant was cleaned-up using a coagulation process, and finally, the decolorized/matrix removed sample solution was processed for LLME for target analyte's pre-concentration. The final extractant was analyzed using UHPLC-MS/MS for OT-A quantification. Under the optimized experimental conditions, highly sensitive detection and quantification limits were obtained at 0.001 and 0.003 ng g^-1 for OT-A with excellent extraction recovery (93-111%) and precision <10%. These results proved that the developed method is a simple, highly sensitive, semi-automated, low-matrix effect and efficient procedure for the determination of mycotoxins in food samples.

Computer-Aided Prediction, Synthesis, and Characterization of Magnetic Molecularly Imprinted Polymers for the Extraction and Determination of Tolfenpyrad in Lettuce

Tolfenpyrad, a pyrazolamide insecticide, can be effectively used against pests resistant to carbamate and organophosphate insecticides. In this study, a molecular imprinted polymer using tolfenpyrad as a template molecule was synthesized. The type of functional monomer and the ratio of functional monomer to template were predicted by density function theory. Magnetic molecularly imprinted polymers (MMIPs) were synthesized using 2-vinylpyridine as a functional monomer in the presence of ethylene magnetite nanoparticles at a monomer/tolfenpyrad ratio of 7:1. The successful synthesis of MMIPs is confirmed by the results of the characterization analysis by scanning electron microscopy, nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, X-ray diffractometer, thermogravimetric analyzer, and vibrational sample magnetometers. A pseudo-second-order kinetic model fit the adsorption of tolfenpyrad, and the kinetic data are in good agreement with the Freundlich isothermal model. The adsorption capacity of the polymer to the target analyte was 7.20 mg/g, indicating an excellent selective extraction capability. In addition, the adsorption capacity of the MMIPs is not significantly lost after several reuses. The MMIPs showed great analytical performance in tolfenpyrad-spiked lettuce samples, with acceptable accuracy (intra- and inter-day recoveries of 90.5-98.8%) and precision (intra- and inter-day relative standard deviations of 1.4-5.2%).

High-throughput screening of 756 chemical contaminants in aquaculture products using liquid chromatography/quadrupole time-of-flight mass spectrometry

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A high-throughput screening method was developed for aquaculture products.

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Modified QuEChERS extraction was used in couple with LC/Q-TOF-HRMS.

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A mega-database was established for 756 multiclass chemical contaminants.

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The method had desirable sensitivity, recovery and repeatability.

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Analysis of real-life samples evidenced applicability of the proposed method.

A high-throughput screening method embracing 756 multiclass chemical contaminants in aquaculture products was developed using modified QuEChERS extraction coupled with liquid chromatography/quadrupole time-of-flight mass spectrometry. A mega-database with retention time/accurate mass data for 524 pesticides, 182 veterinary drugs, 32 persistent organic pollutants and 18 marine toxins was established for compound identification via retrospective library searching. In the four representative matrices (muscle tissues of tilapia and grouper, and edible portions of oyster and scallop), all the database compounds showed acceptable recovery and repeatability with the screening detection limit and limit of quantification below 0.01 mg/kg for >90% of them. The matrix-matched calibration revealed acceptable quantitative property of the method in terms of linear range, linearity, and matrix effect, and fish muscle samples showed stronger matrix effect than shellfish samples. Analysis of 64 real-life samples from aquaculture farms and retail markets evidenced applicability of the proposed method to high-throughput screening scenarios.

Simultaneous Determination of Seven Pesticides and Metabolite Residues in Litchi and Longan through High-Performance Liquid Chromatography-Tandem Mass Spectrometry with Modified QuEChERS

This study established a QuEChERS high-performance liquid chromatography/tandem triple-quadrupole mass spectrometry method for determining azoxystrobin, pyraclostrobin, picoxystrobin, difenoconazole, chlorantraniliprole, imidacloprid, and cyantraniliprole and its metabolite (IN-J9Z38) in litchi and longan, and applied this method to the real samples. The residues in samples were extracted with acetonitrile and purified with nano-ZrO2, C18, and PSA. The samples were then detected with multireactive ion monitoring and electrospray ionization in the positive ion mode and quantified using the external matrix-matched standard method. The results showed good linearities for the eight analytes in the range of 1−100 μg/L, with correlation coefficients (r2) of >0.99. The limit of quantification was 1−10 μg/kg, and the limit of detection was 0.3−3 μg/kg. Average recovery from litchi and longan was 81−99%, with the relative standard deviation of 3.5−8.4% at fortified concentrations of 1, 10, and 100 μg/kg. The developed method is simple, rapid, efficient, and sensitive. It allowed the rapid screening, monitoring, and confirming of the aforementioned seven pesticides and a metabolite in litchi and longan.

Prolonged on-tree maturation vs. cold storage of Hass avocado fruit: Changes in metabolites of bioactive interest at edible ripeness

When the recipient of the product is relatively distant from the production area, it is necessary to use cold storage and controlled humidity to transport the avocado fruits. One of the main advantages of local avocado consumption lies on the possibility of prolonging on-tree maturation; this could foreseeably modify the metabolic profile of the fruit that reaches the consumer. In this work, the effect of prolonged on tree maturation (during different time intervals) on the final composition of avocado fruit (at edible ripeness) was evaluated and compared with the impact of the same periods after prolonged cold storage. The quantitative evolution of nine bioactive metabolites (7 phenolic compounds, pantothenic and abscisic acids) over 40 days (10-days intervals) was studied by using a solid-liquid extraction protocol and a LC-MS methodology. The results were discussed both considering the quantitative evolution of each individual compound and the sum of all of them.

Estimation of residue levels and dietary risk assessment of cyproconazole and azoxystrobin in cucumber after field application in China

Residue field trials in cucumber were conducted for the safe use of a commercial formulation of cyproconazole·azoxystrobin 28% suspension concentrate (SC 294 g a.i. ha^-1, three applications at a 7-day interval) in the year 2018, in China. To determine the residues of cyproconazole and azoxystrobin in cucumber, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed using high-performance liquid chromatography coupled with tandem mass spectrometry. This validated method was applied to analyze cucumber samples collected from 12 specified regions. At the 3-day interval to harvest, the highest residue (HR) of azoxystrobin was 0.150 mg kg^-1, which was lower than the maximum residue limit (MRL; 0.5 mg kg^-1) permitted in China, and the HR of cyproconazole was 0.084 mg kg^-1, for which no MRL value has been set in China. The chronic risk quotient values of cyproconazole and azoxystrobin for Chinese adults at a 3-day interval to harvest were 2.56% and 13.72%, respectively. The acute risk quotient values of cyproconazole in cucumber were specified as 5.52% for children (1-6 years old) and 2.83% for the adults (> 18 years old) in China. These results indicate that cyproconazole·azoxystrobin 28% SC sprayed on cucumber at the pre-harvest interval of 3 days has no significant potential risk for Chinese consumers.

Determination of phthalic acid esters and di(2-ethylhexyl) adipate in coffee obtained from capsules

In this work, the ammonium formate version of the QuEChERS method has been applied for the first time to the extraction of a group of nine phthalic acid esters and one adipate from three types of coffee (maximum intensity, intermediate intensity and decaffeinated) prepared from coffee capsules, using gas chromatography coupled to mass spectrometry for analytes separation and determination. Matrix-matched calibration showed good linearity with determination coefficients (R²) higher than 0.9983 for all analytes and matrices. In general, matrix effect assessment revealed a medium effect of signal suppression, while mean relative recovery values were in the range 70-120% with relative standard deviation values ≤19% for most analytes. Several samples of each type of coffee obtained from capsules made of different materials were also analysed, finding concentrations of DBP, DEHA and DEHP in the range 29.3-734 ng/capsule, below the tolerable daily intake established for some of them.

Dissipation and dietary risk assessment of carbendazim and epoxiconazole in citrus fruits in China

BACKGROUND

Carbendazim and epoxiconazole are widely applied to control anthracnose and sand bark fungal diseases in citrus. The residues of these two fungicides in citrus and their potential risk to consumers have generated much public concern. We therefore sought to investigate the dissipation, residue, and dietary risk assessment of carbendazim and epoxiconazole in citrus.

RESULTS

The dissipation kinetics and residue levels of carbendazim and epoxiconazole in citrus under field conditions were measured using dispersive solid-phase extraction and ultra-high-performance liquid chromatography-tandem mass spectrometry. The citrus samples were extracted with acetonitrile and purified by primary secondary amine sorbent. The mean recoveries of carbendazim and epoxiconazole ranged from 86.2 to 105.6% and relative standard deviations were ≤9.8%. The half-lives of carbendazim and epoxiconazole in whole citrus ranged from 2.0 to 18.0 days. Hazard quotient (HQ) and risk quotient (RQ) models were applied to whole citrus for dietary exposure risk assessment based on the terminal residue test. Hazard quotients ranged from 0.066 to 0.134% and RQs from 18.48 to 82.12%.

CONCLUSION

Carbendazim and epoxiconazole in citrus degraded rapidly following first-order kinetics models. The dietary risk of exposure to both carbendazim and epoxiconazole through citrus, based on HQ and RQ, was acceptable for human consumption. This study indicates scientifically validated maximum residue limits in citrus, which are currently lacking for epoxiconazole in China. © 2021 Society of Chemical Industry.

Targeted screening of 11 bisphenols and 7 plasticizers in food composites from Canada and South Africa

A sensitive method based on ultrasound-assisted liquid extraction coupled with liquid chromatography was applied to screen 18 plastic-related contaminants in 168 food composites (namely fish fillets, chicken breast, canned tuna, leafy vegetables, bread and butter) collected in Montreal (Canada), Pretoria and Vhembe (South Africa). Bisphenol A (BPA), bisphenol S (BPS) and seven plasticizers (di-n-butyl phthalate (DBP), diethyl phthalate (DEP), (2-ethylhexyl) phthalate (DEHP), di-(2-ethylhexyl) adipate (DEHA), di-isononyl phthalate (DINP), di-(isononyl)-cyclohexane-1,2-dicarboxylate (DINCH)) were detected in different foods from both countries. DBP and DEP were the most frequently detected contaminants in food collected in Montreal (75% for both) and DINP was the most frequently detected contaminant in food from South Africa (67%). DEHA concentration in packaged fish were significantly higher than the values for non-packaged fish (p < 0.01) suggesting that the packaging film can be one source of DEHA in fish.

Residue, dissipation and dietary intake risk assessment of tolfenpyrad in four leafy green vegetables under greenhouse conditions

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A QuEChERS-GC–MS/MS method was used to detect tolfenpyrad in leafy green vegetables.

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Half-lives of tolfenpyrad were 2.0–6.8 d in greenhouse-grown leafy green vegetables.

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PHI of tolfenpyrad was suggested as 21 d in BCL and 28 d in BBL, SOL and LSL.

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The potential health risk of tolfenpyrad was acceptable in leafy green vegetables.

A novel and accurate analytical method for the determination of tolfenpyrad in four leafy green vegetables, Brassica bara L., Spinacia oleracea L., Lactuca sativa L. and Brassica chinensis L., was developed and applied to investigate the residue distribution and dietary risk under greenhouse conditions. The established approach was determined to be adequate, with recoveries of 79.2%–92.9% and relative standard deviations < 8%. Tolfenpyrad dissipated relatively rapidly in four leafy green vegetables. Terminal residues of tolfenpyrad were below 0.5 mg/kg (maximum residue limit for Brassica bara L. set by China) in leafy green vegetables collected 28 d after the last application. Due to risk quotient values < 100%, the residue levels of tolfenpyrad in leafy green vegetables collected 21 days after the last application were deemed safe for consumers. The results provide field data for the reasonable use and dietary risk assessment of tolfenpyrad in leafy green vegetables.

Accurate Determination of 12 Lactones and 11 Volatile Phenols in Nongrape Wines through Headspace-Solid-Phase Microextraction (HS-SPME) Combined with High-Resolution Gas Chromatography-Orbitrap Mass Spectrometry (GC-Orbitrap-MS)

This paper clarifies the contribution of lactones and volatile phenols to the aroma of nongrape wine. A target method for the simultaneous determination of these two kinds of volatiles in nongrape wines was developed using headspace-solid-phase microextraction (HS-SPME) combined with high-resolution gas chromatography-Orbitrap mass spectrometry (GC-Orbitrap-MS). A high-resolution mass spectrometry database including 12 lactones and 11 volatile phenols was established for qualitative accuracy. Different matrix-matched calibration standards should be prepared for specific samples due to the matrix effects. The method was successfully validated and applied in three nongrape wines. Hawthorn wine contained more lactones (δ/γ-hexalactone, δ/γ-nonalactone, δ/γ-decalactone, γ-undecalactone, δ/γ-dodecalactone, C10 massoia lactone, and whiskey lactone), while blueberry wine contained more volatile phenols (especially 4-vinylguaiacol and 4-ethylguiaiacol). Goji berry wines contained certain concentrations of δ-nonalactone, γ-nonalactone, δ-hexalactone, and 3-ethyl phenol. This study demonstrated that HS-SPME-GC-Orbitrap-MS can be applied for the accurate quantification of trace aroma compounds such as lactones and volatile phenols in fruit wines.

Simultaneous determination of pesticides from soils: a comparison between QuEChERS extraction and Dutch mini-Luke extraction methods

The expanding nature of the agricultural sector has fuelled the intensification of plant protection products usage, including pesticides. These pesticides may persist in soils, necessitating their accurate determination in a variety of soil types. However, due to their complex nature, the effective extraction of pesticide residues from soil matrices can present challenges to pesticide detection and quantification. This research compared two well-known extraction methods, QuEChERS and Dutch mini-Luke, by assessing their specificity, sensitivity, accuracy, precision and reproducibility in extracting seven distinct pesticides with a range of chemico-physical characteristics from Irish soils. The HPLC-UV conditions were optimised to separate the seven pesticides, and it was shown that both extraction methods successfully extracted neonicotinoids with recovery values ranging between 85 and 115%. Fluroxypyr and prothioconazole could not be efficiently extracted using QuEChERS, however, the recovery values of both the analytes ranged between 59 and 117% using Dutch mini-Luke. Furthermore, with the exception of prothioconazole using Dutch mini-Luke, both extraction methods resulted in reproducibility and precision values below or equal to 20%. Lastly, Dutch mini-Luke is noted to have a lower matrix effect than QuEChERS, except for prothioconazole. The comparison results showed that Dutch mini-Luke resulted in superior method sensitivity, better recovery, and lower matrix effect towards most investigated analytes and was the only extraction technique that successfully extracted all pesticides analysed in soil matrices.

Probabilistic health risk assessment based on Monte Carlo simulation for pesticide residues in date fruits of Iran

The validation of an analytical procedure based on the quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach is presented for multiresidue analysis of pesticides in dates by liquid chromatography-tandem mass spectrometry (UHPLC-MS²). The proposed methodology was applied for simultaneous quantification of 16 pesticides in 50 different date fruits. Method validation was performed regarding accuracy, precision, LDR, LOD, and LOQ, as well as matrix effects. Results of validation were satisfactory, with recoveries higher than 80% for 75% of the samples for 100- and 500- μg L^-1 spike levels. Evaluation of the matrix effect revealed that for 81% of the samples, a slight matrix effect was observed. Residues in 92% of the real samples were found below national MRLs. Afterward, hazard quotient (HQ) and total hazard quotient (THQ) of human health risk assessment of pesticides was estimated using a probabilistic approach based on the Monte Carlo (MC) algorithm. Total hazard quotient (THQ) in adults based on the consumption of dates in total samples was estimated to be 7.8% and 36.7% for adults and children, respectively. Since the studied pesticides are registered in the country and are the most widely used pesticides on dates, the occurrence of other pesticide residues seems to be unlikely. Consequently, the applied health risk assessment on Iranian date fruit samples showed that the HQ for adults and children populations indicates no risk to human health.

Enantioseparation and determination of triazole fungicides in fruit juice by aqueous biphasic system coupled with HPLC-MS/MS

The aqueous biphasic system based on choline ionic liquids and ethylene/propylene oxide copolymer coupled with high-performance liquid chromatography-tandem mass spectrometry was developed for the simultaneous determination of the enantiomers of two fungicides: myclobutanil and tebuconazole. The influence of mass fractions of ionic liquids and the copolymer on the extraction efficiency of the target fungicides was investigated. The analytes are mainly concentrated in the bottom, copolymer-rich phase. The extraction efficiencies of the selected fungicides were significantly affected by the concentrations of the copolymer, and their extraction efficiencies decreased with the higher mass fractions of the copolymer, while the mass fraction of ionic liquids had little effect on their extraction behavior. Excellent extraction efficiency was achieved using the aqueous biphasic system based on choline L-lysinate and the copolymer. At three spiked concentrations of 0.01, 0.05, and 0.1 mg/kg, the average recoveries of the selected fungicides ranged from 80 to 89%, with the relative standard deviations in the range of 2.1-5.3%. Limits of quantitation for the enantiomers of tebuconazole and myclobutanil were 0.5 and 5.0 µg/kg, respectively. The developed system could be successfully applied to the analysis of triazole fungicides residue in real samples.

Pesticide residues in tomato crops in Western Algeria

This study aimed to evaluate levels of pesticide residues commonly used on tomato crops in Western Algeria. It showed a significant use of pesticides, especially insecticides (47%) and fungicides (41%) among listed pesticides in crop fields. A total of 30 tomato samples were analysed using multi-residue analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after QuEChERS extraction. Five pesticides (difenoconazole, triadimenol, metalaxyl, chlorpyriphos and methomyl) were detected in 14 samples (47%). Among these five samples containing residues of two different types of pesticides. The levels ranged from 2.29 to 64.3 µg/kg. The methomyl residue in one sample was above the maximum limit (MRLs) set by the European Union. Our results indicate an excessive use of pesticides and undeniable non-compliance with good agricultural practices. Routine monitoring for pesticides is recommended to preserve consumer's health.

[Determination of myclobutanil enantiomers in wheat and its processed products by ultraperformance liquid chromatography-tandem mass spectrometry based on a chiral stationary phase]

A valid method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with a chiral stationary phase was established for the determination of myclobutanil enantiomer residue in wheat grain and its processed products (flour, bran, pasta, steamed bun, noodle, and cooking water). The wheat grain and processed product samples were extracted with acetonitrile and purified with primary secondary amine (PSA) and C18. The enantiomers of myclobutanil were separated by Chiral column Lux Cellulose-1 (150 mm×2.0 mm, 3 μm, Phenomenex). The column temperature, sample volume injected, and flow rate were 30 ℃, 5 μL, and 0.25 mL/min, respectively. The mobile phase consisted of phase A (25%), water with 0.1% formic acid and 4 mM ammonium acetate, and phase B (75%), methanol with 0.1% formic acid and 4 mM ammonium acetate. A Waters Xevo TQ-S Micro MS/MS system (Waters, USA) was used for mass spectrometric analysis. An electrospray ionization (ESI) source operating in the positive ionization mode. MS analyses were performed in the multiple reaction monitoring (MRM) mode. The qualitative ions of myclobutanil were m/z 288.9/69.9 and 288.9/124.9, and the quantitative ion of myclobutanil was m/z 288.9/69.9. The source voltage was 3000 V, and the desolvation temperature was 400 ℃. The desolvation gas flow was 800 L/h, and the source temperature was 150 ℃. The matrix effect of wheat grains and their processed products on the determination of myclobutanil enantiomers by UPLC-MS/MS was investigated. S-(+)-myclobutanil and R-(-)-myclobutanil had a mid signal suppression effect on wheat grain, bran, pasta, steamed bun, and noodle, while S-(+)-myclobutanil and R-(-)-myclobutanil had a mid signal enhancement effect on flour and cooking water. Finally, the matrix-matched calibration method was effective in all matrices and was selected for the quantification of the myclobutanil enantiomer residue in the samples. The results showed that the two enantiomers of myclobutanil were well separated by this method. The first and second eluted enantiomers were S-(+)-myclobutanil and R-(-)-myclobutanil, respectively, with the corresponding retention times being 4.34 min and 5.13 min. The limits of detection (LOD) and limits of quantification (LOQ) of S-(+)-myclobutanil and R-(-)-myclobutanil in wheat and its processed products were 0.2 μg/kg and 0.5 μg/kg, respectively. In the linear range of 0.5-25 μg/L, the peak areas of the myclobutanil enantiomers showed a good linear relationship with the concentration, and the R2 values were all greater than 0.99. At fortification levels of 5, 50, and 100 μg/kg (enantiomer concentration), the average recoveries of S-(+)-myclobutanil in wheat grain and its processed products ranged from 82% to 110%, with RSDs between 0.9% and 6.8%. The average recoveries of R-(-)-myclobutanil in wheat grain and its processed products ranged from 80% to 109%, with RSDs between 0.9% and 6.8%. This method fulfils the requirements for pesticide residue analysis. The established method was applied to analyze five flour samples, two noodle samples, and two steamed bread samples. The results showed that S-(+)-myclobutanil and R-(-)-myclobutanil enantiomers were not detected in the samples. In this study, methods for the enantiomeric separation and residue analysis of myclobutanil in wheat were evaluated at the enantiomeric level, which enriched the methods of enantiomeric separation and residue analysis of chiral pesticide myclobutanil enantiomers in raw agricultural product (wheat grain) and its processed foods. This method is effective for the residue analysis of chiral pesticide myclobutanil enantiomers in raw agricultural commodities and its processed products.

Relationship between imidacloprid residues and control effect on cotton aphids in arid region

In this case, the dissipation and residues of imidacloprid as well as its control efficacy against aphids (Aphis gossypii Glover) in cotton cropping system were reported. After the final spray at the rates of 10.5-42.5 g a.i. ha^-1, the initial deposits were 0.59-2.25 mg kg^-1 with half-lives of 2.12-2.84 days on leaves and 0.06-0.21 mg kg^-1 with half-lives of 1.51-4.20 days in soil, respectively. The initial residues were significantly higher with longer persistence in the upper position of the leaf than in middle and lower positions. The different application dosages could induce a significant difference in the initial deposits, but not show consistent correlation with the dissipation rate. The repeated applications of imidacloprid could alter its residue levels and dissipation rates. The long-term residue concentrations of imidacloprid (60 days after the final application) reached to the nondetectable level in soil. Combined with the control efficacy results, it was considered that the recommended dose of imidacloprid on cotton could be used effectively and safe in this arid area from the view of crop protection and environmental contamination.

Rapid MSPD-LC-MS/MS Procedure for Determination of Pesticides in Potato Tubers

The program of potato protection recommended by the producers of agrochemicals requires application: thiamethoxam, lambda-cyhalothrin, deltamethrin, rimsulfuron and metalaxyl. Therefore, there is a risk that these pesticides are present in tubers, thus posing a toxicological risk to the consumer. In this respect, it is necessary to monitor the presence of these compounds in edible plants. Therefore, the aim of this paper was to develop a novel, simple and robust analytical procedure for simultaneous determination of above-mentioned pesticides in potato tubers. To develop an analytical procedure that fulfills SANTE demands, quick, easy, cheap, effective, rugged and safe method and matrix solid phase dispersion technique were investigated. The final determination was conducted by liquid chromatography with tandem mass spectrometry. The obtained experimental data were analyzed by analysis of variance. For the extraction of analytes, matrix solid phase dispersion with octadecyl sorbent and methanol as eluent was chosen, since it provides the validation parameters according to SANTE requirements (recovery: 77-111%, relative standard deviation: 1-10%, limit of quantification: 0.9-5.0 μg/kg). This innovative analytical procedure is a practical analytical tool, which was successfully proven by applying it for target pesticides determination in potato tuber samples of different varieties randomly chosen at local markets.

A comparison of the effectiveness of QuEChERS, FaPEx and a modified QuEChERS method on the determination of organochlorine pesticides in ginseng

This study provides a review of methods used in the determination of organochlorine pesticides (OCPs) in ginseng and compares the effectiveness of three extraction methods (Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), a modified QuEChERS and a Fast Pesticide Extraction (FaPEx)) in the analyses of 20 OCPs in ginseng root samples. For each method, sample mass, solvent volume and sorbent mass were varied to identify the optimum combination to effectively isolate analytes of interest from the complex sample matrix. Extracts were analyzed using the gas chromatography-μ-electron capture detector (GC-μ-ECD), and confirmatory analyses performed by gas chromatography-tandem-mass spectrometry (GC-MS/MS). Eighteen out of 20 OCPs spiked onto in-house prepared ginseng samples produced acceptable recoveries (51-156%) when extracted using QuEChERS and FaPEx. All 20 analytes, including dichlorodiphenyldichloroethane (p, p'- DDD) and dichlorodiphenyltrichloroethane (o, p'-DDT), produced acceptable recoveries (51-129%) with the use of a modified QuEChERS method. The applicability of the modified QuEChERS method was demonstrated through the analysis of ginseng samples grown in endosulfan-treated soil. The samples were analyzed by both GC-μ-ECD and GC-MS/MS with no significant difference identified in the results of each analytical method. This study highlights the applicability of the modified QuEChERS method, in combination with GC- μ-ECD, to determine organochlorine pesticides in ginseng. This may be especially useful for laboratories in developing countries and less advanced institutions without access to MS/MS instrumentation.

Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Analysis of 353 Pesticides in the Edible Insect Tenebrio molitor Larvae (Mealworms)

Tenebrio molitor larvae (mealworm) is an edible insect and is considered a future food. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), a novel method for simultaneous analysis of 353 target analytes was developed and validated. Various sample preparation steps including “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) extraction conditions, number of acetonitrile-hexane partitions, and dispersive-solid phase extraction (dSPE) sorbents were compared, and the optimal conditions were determined. In the established method, 5 g of homogenized mealworms was extracted with acetonitrile and treated with QuEChERS EN 15662 salts. The crude extract was subjected to three rounds of acetonitrile-hexane partitioning, and the acetonitrile layer was cleaned with C18 dSPE. The final solution was matrix-matched and injected into LC-MS/MS (2 μL). For target analytes, the limits of quantitation (LOQs) were ≤10 μg/kg, and the correlation coefficient (r²) of calibration was >0.990. In recovery tests, more than 90% of the pesticides showed an excellent recovery range (70–120%) with relative standard deviation (RSD) ≤20%. For more than 94% of pesticides, a negligible matrix effect (within ±20%) was observed. The analytical method was successfully applied and used for the detection of three urea pesticides in 4 of 11 mealworm samples.

Comprehensive investigation of lactones and furanones in icewines and dry wines using gas chromatography-triple quadrupole mass spectrometry

A number of lactones and furanones associated with pleasant odorants play a vital role in grape and wine aroma profiles. However, they are usually present at trace levels and are particularly challenging to measure. In this work, an optimized method based on solid-phase extraction (SPE) coupled with gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS) was developed for simultaneous determination of 14 lactones and 3 furanones. The validation was carried out using different types of wine as matrices, and satisfactory linearity, sensitivity, trueness and precision were confirmed. Furaneol and sotolon showed significantly lower limits of detection (LODs) in three real wines compared to model wine due to the matrix effect. Furthermore, the method was successfully applied to investigate the concentration range of lactones and furanones in several icewines, dry red and white wines. Icewines contained higher concentrations of most lactones and furanones compared with dry red and white wines. Partial least squares-discriminate analysis (PLS-DA) also indicated that γ-hexa-, γ-octa-, γ-nona-, γ-deca-, δ-hexa-, and δ-decalactone, as well as 5,6-dihydro-6-pentyl-2H-pyran-2-one (C10 massoia lactone), sotolon and homofuraneol contributed greatly to the discrimination between icewines and dry wines. Moreover, the calculation of odor activity value (OAV) suggested that γ-octa-, γ-nona-, and γ-decalactone, as well as furaneol and homofuraneol contributed greatest to the aroma of icewines.

Comprehensive assessment for the residual characteristics and degradation kinetics of pesticides in Panax notoginseng and planting soil

Incorrect and excess usage of pesticides during crop cultivation poses a serious threat to human health and ecosystems. In this study, we tested for the presence of 201 pesticide residues in 90 batches of Panax notoginseng (P. notoginseng) and 10 batches of planting soil. Pesticide residue characteristics and the relationship between pesticides present in P. notoginseng and the soil were discussed. Twenty-nine pesticides were detected in P. notoginseng samples and 15 pesticides were found in the soil samples. In P. notoginseng samples, the 68.9% of the identified pesticides were fungicides, and six fungicides (procymidone, iprodione, pyrimethanil, propiconazole, dimethomorph and tebuconazole) were found in >90% of the samples. Nine insecticides were found, with one insecticide, chlorpyrifos, detected in 93.3% of the P. notoginseng samples. The residual concentrations of 17 pesticides were found at levels exceeded the "non-Chinese" maximum residue levels (MRLs) for Ginseng and 17 pesticides were found at levels exceeding the MRLs set by China for "pollution-free" P. notoginseng. We observed no significant differences in pesticide residues were found on P. notoginseng from different cultivation areas. We also analyzed the degradation kinetics of pesticides in the soil, as well as their bioconcentration factors (BCFs), and found that the fungicides iprodione and myclobutanil displayed strong uptake from the soil to the root of P. notoginseng. Together, our data suggest that fungicides should be considered as key monitoring substances in P. notoginseng and planting soil.

Selective Detection of Folic Acid Using 3D Polymeric Structures of 3-Carboxylic Polypyrrole

The detection of folic acid in biological samples or pharmaceutical products is of great importance due to its implications in the biological functions of the human body, along with the development and growth of the fetus. The deficiency of folic acid can be reversed by the intake of different pharmaceutical formulations or alimentary products fortified with this molecule. The elaboration of sensing platforms represents a continuous work in progress, a task in which the use of conductive polymers modified with different functionalities represents one of the outcoming strategies. The possibility of manipulating their morphology with the use of templates or surfactants represents another advantage. A sensing platform based on carboxylic functionalized polypyrrole was synthesized via the electrochemical approach in the presence of a polymeric surfactant on a graphite-based surface. The sensor was able to detect the folic acid from 2.5 μM to 200 μM with a calculated limited of detection of 0.8 μM. It was employed for the detection of the analyte from commercial human serum and pharmaceutical products with excellent recovery rates. The results were double checked using an optimized spectrophotometric procedure that confirmed furthermore the performances of the sensor related to real samples assessment.

Extraction of Phthalic Acid Esters and Di(2-ethylhexyl) Adipate from Tap and Waste Water Samples Using Chromabond® HLB as Sorbent Prior to Gas Chromatography-Mass Spectrometry Analysis

In this work, Chromabond® HLB was evaluated as an extraction sorbent of a group of seven phthalic acid esters (PAEs; i.e., dipropyl phthalate, DPP, dibutyl phthalate, DBP, diisopentyl phthalate, DIPP, di-n-pentyl phthalate, DNPP, butylbenzyl phthalate, BBP, dicyclohexyl phthalate, DCHP, and di(2-ethylhexyl)phthalate, DEHP) and one adipate (di(2-ethylhexyl) adipate, DEHA) from tap and waste water prior to gas chromatography-mass spectrometry. After the optimization of the extraction conditions (200 mg of sorbent conditioned with 10 mL of acetonitrile and 2 mL of Milli-Q water, extraction of 50 mL of water at pH 6.0, vacuum drying for 20 min and elution with 10 mL of ethyl acetate), a recovery study was developed at different concentration levels in each matrix, which revealed that most of the target analytes could be recovered between 75 and 112%, with relative standard deviation values for all of them below 20%. Matrix effect was evaluated, finding that matrix-matched calibration should be developed for most analytes in both matrices. The limits of quantification (LOQs) of the method were in the 0.82–71 ng L−1 range. The developed method was also applied to the extraction of the target PAEs in different water samples finding some of them, in particular, DNPP in tap water samples, and BBP and DCHP in waste water, but below the LOQs of the method.

A Study of Opiate, Opiate Metabolites and Antihistamines in Urine after Consumption of Cold Syrups by LC-MS/MS

Studying the origin of opiate and/or opiate metabolites in individual urine specimens after consumption of cold syrups is vital for patients, doctors, and law enforcement. A rapid liquid chromatography-tandem mass spectrometry method using "dilute-and-shoot" analysis without the need for extraction, hydrolysis and/or derivatization has been developed and validated. The approach provides linear ranges of 2.5-1000 ng mL^-1 for 6-acetylmorphine, codeine, chlorpheniramine, and carbinoxamine, 2.5-800 ng mL^-1 for morphine and morphine-3-β-d-glucuronide, and 2.5-600 ng mL^-1 for morphine-6-β-d-glucuronide and codeine-6-β-d-glucuronide, with excellent correlation coefficients (R² > 0.995) and matrix effects (< 5%). Urine samples collected from the ten participants orally administered cold syrups were analyzed. The results concluded that participants consuming codeine-containing cold syrups did not routinely pass urine tests for opiates, and their morphine-codeine concentration ratios (M/C) were not always < 1. In addition, the distribution map of the clinical total concentration of the sum of morphine and codeine against the antihistamines (chlorpheniramine or carbinoxamine) were plotted for discrimination of people who used cold syrups. The 15 real cases have been studied by using M/C rule, cutoff value, and distribution map, further revealing a potential approach to determine opiate metabolite in urine originating from cold syrups.

Simultaneous analysis of seven neonicotinoid pesticides in agricultural products involving solid-phase extraction and surrogate compensation using liquid chromatography-tandem mass spectrometry

This study proposes a practical and precise method for the simultaneous analysis of seven neonicotinoid pesticides in agricultural products using liquid chromatography-tandem mass spectrometry from two different approaches. First, the applicability of a cleanup cartridge, comprised of a polymer sorbent consisting of a styrene-divinylbenzene copolymer with N-containing polar groups and methacrylate, in food samples was demonstrated for the first time. Second, applying an internal standard (IS) calibration method at a lower cost was considered by changing the timing of the IS addition and selecting the minimum number of ISs by referring on the matrix effect. The proposed method resulted in excellent recoveries in all tested matrices (brown rice, grapes, and peanuts) at a spiked concentration of 0.01 mg/kg. Subsequently, a residue analysis of hagobou (young burdock) was conducted. Imidacloprid was detected at 0.02 mg/kg, and the recoveries calculated in parallel with the analysis were satisfactory.

An electroanalytical platform for nereistoxin-related insecticide detection based on DNA conformational switching and exonuclease III assisted target recycling

In this work, an electroanalytical platform for nereistoxin (NRT)-related insecticide detection is proposed on the basis of NRT induced DNA conformational switching and exonuclease III (Exo III) assisted target recycling. NRT-related insecticides were first hydrolyzed and converted into NRT with two thiol groups (-SH). Then, a cytosine-Ag+-cytosine (C-Ag+-C) mismatched base pair was adopted to induce a blunt-ended hairpin configuration of HP DNA. In the presence of converted NRT, it could take up Ag+ from HP DNA to change its conformation from a hairpin to single-stranded structure (HP ssDNA). Thereafter, the obtained HP ssDNA was further hybridized with an H1 hairpin probe on the electrode surface to trigger the Exo III cleavage process, releasing HP ssDNA for recycling leaving the G-quadruplex fragment of H1, which was used for hemin/G-quadruplex complex formation. The reversible redox reaction of Fe(iii)/Fe(ii) of hemin gave a remarkable electrochemical response for quantitative determination of the NRT-related insecticides. As an analytical model, a low detection limit of 3.9 ng L-1 and a wide linear range of 0.01-1500 μg L-1 with excellent selectivity were achieved for cartap detection. The proposed method also displayed great applicability for cartap detection in agricultural products.