Evaluation of cleanup procedures in pesticide multi-residue analysis with QuEChERS in cinnamon bark

Exploration of a modified pretreatment process coupled with GC-MS/MS for determination of 18 phthalates in edible oils

Phthalates (PAEs), which are pollutants that most easily migrate from plastic packages to edible oils, have received increasing attention. In this work, a sample preconditioning method was proposed and explored, involving a single-step extraction using a methanol and ethyl hexanoate mixed solvent, followed by clean-up with a mixed absorbent of graphitic carbon nitride (g-C3N4) and N-propyl ethylenediamine (PSA), for the determination of 18 PAEs in oil samples through GC-MS/MS analysis. The triazine ring structure and conjugated aromatic heterocyclic accumulation structure of g-C3N4 and the amino-rich structure of PSA can provide hydrogen bonds, conjugated π-π interactions, and hydrophobic effects for the removal of interferences such as organic acids, aliphatic acids, and pigments. To achieve optimal analytical performance, key extraction and purification parameters that may affect the pretreatment efficiency-such as the extraction solution, its volume ratio, extraction temperature, extraction time, and the amount of the clean-up absorbent-were systematically explored and optimized. When applied to edible oil analysis, an excellent linear range from 0.2 to 8.0 mg kg-1 with a preferable coefficient of determination (R2 > 0.9989) and satisfactory sensitivity (LOD and LOQ ranging from 0.0002 mg kg-1 to 0.08 mg kg-1 and 0.0004 mg kg-1 to 0.2 mg kg-1, respectively) were obtained. Moreover, a relatively satisfactory recovery varying from 71.4% to 107.9% and the corresponding repeatability ranging from 0.3% to 6.8% were acquired. Furthermore, this work offers a new idea for exploring the application of novel nanocomposites in the pretreatment process.

A convenient and effective method for determining organophosphorus pesticides in citrus fruits based on a novel dispersive solid phase extraction using UiO-66/Alg bead as the sorbent

This work presents a novel, convenient and effective method for assaying organophosphorus pesticides (OPPs) in the pulp and peel of citrus fruits. In this method, shaped UiO-66/alginate (UiO-66/Alg) beads were employed to replace the powder sorbents used in traditional dispersive solid phase extraction (d-SPE) methods. The UiO-66/Alg beads can be easily separated by only using a tweezer within 1 min, which effectively simplifies the sample pretreatment and overcomes the shortages brought by the incomplete separation of powder sorbents. Moreover, the matrix compounds can be effectively excluded by UiO-66/Alg beads, and the UiO-66/Alg beads can be reused at least 8 times. The d-SPE conditions were optimized by a single factor test. The method shows satisfactory sensitivity, accuracy and precision. Furthermore, ATR-FTIR and UV-Vis-DRS were employed to investigate the adsorption mechanism. Finally, the developed method was applied to monitor the OPPs in ten different citrus fruits.

Determination of quinclorac and quinclorac methyl ester in honey by online SPE-UPLC-MS/MS

A method employing online solid phase extraction (SPE) coupled to UPLC-MS/MS was developed for the determination of residues of the acid herbicide quinclorac plus its transformation product, quinclorac methyl ester, in honey. The analytical method involved dissolving the honey in a mixture of methanol:water followed by direct injection into a two-dimensional UPLC system which is used to perform an automated SPE cleanup on a reusable phenyl cartridge prior to the target analytes being transferred onto an analytical UPLC column for subsequent chromatographic separation followed by MS/MS detection. The limits of quantitation for quinclorac and quinclorac methyl ester in honey were both set at 0.5 µg kg-1 and the method detection limit was estimated to be 0.012 µg kg-1 for each compound. The working analytical range (0.5-100 µg kg-1) was validated by analysing a series of spiked replicate honey samples. The method was applied to the analysis of various honeys obtained from numerous different commercial sources. Quinclorac was detected in 9 out of 30 samples at concentrations ranging from 0.6 to 31.5 µg kg-1. Quinclorac methyl ester, which is estimated to be significantly more toxic than the parent herbicide itself, was not detected in any honey sample.

Application of Sorbent-Based Extraction Techniques in Food Analysis

This review presents an outline of the application of the most popular sorbent-based methods in food analysis. Solid-phase extraction (SPE) is discussed based on the analyses of lipids, mycotoxins, pesticide residues, processing contaminants and flavor compounds, whereas solid-phase microextraction (SPME) is discussed having volatile and flavor compounds but also processing contaminants in mind. Apart from these two most popular methods, other techniques, such as stir bar sorptive extraction (SBSE), molecularly imprinted polymers (MIPs), high-capacity sorbent extraction (HCSE), and needle-trap devices (NTD), are outlined. Additionally, novel forms of sorbent-based extraction methods such as thin-film solid-phase microextraction (TF-SPME) are presented. The utility and challenges related to these techniques are discussed in this review. Finally, the directions and need for future studies are addressed.

Pesticide residue analysis in different spice samples by automatic µSPE clean-up workflow determination using LC-MS/MS

Spices such as paprika, curry, turmeric, dry chilli, and black pepper are grown in various geographic locations and widely used by consumers across the world. Pesticides applied during crop production practices could contaminate the produce, affecting the quality and posing a health risk for consumers. The complexity of the spice matrix and the wide range of target pesticides potentially present require special sample extraction and clean-up treatments to overcome matrix interference and ion suppression. In this study, sample extracts from spice matrices (paprika/curry/turmeric/dry chilli/black pepper) were cleaned up by an automated µSPE clean-up method for multi-residue analysis of pesticides using LC-MS/MS. The automated µSPE clean-up method involves pre-filled cartridges containing various sorbent materials suitable for numerous co-extractives and the automated clean-up process was carried out using an autosampler. The regulatory limit for pesticides in spices varies with type, with a low MRL of 0.05 mg kg-1 or higher for 99% of the analytes. At spiking concentrations of 0.05 and 0.1 mg kg-1, good recoveries between 70 and 120% with RSD values below 20% were achieved for more than 98% of the compounds. With automatic clean-up of samples that takes 5 min/sample, 20% increased output per day shows an important advantage achieved compared to manual clean-up.

Established and emerging organophosphate esters (OPEs) and the expansion of an environmental contamination issue: A review and future directions

The list of organophosphate esters (OPEs) reported in the environment continues to expand as evidenced by the increasing number of OPE studies in the literature. However, there remains a general dearth of information on more recently produced and used OPEs that are proving to be emerging environmental contaminants. The present review summarizes the available studies in a systematic framework of the current state of knowledge on the analysis, environmental fate, and behavior of emerging OPEs. This review also details future directions to better understand emerging OPEs in the environment. Firstly, we make recommendations that the current structural/practical abbreviations and naming of OPEs be revised and updated. A chemical database (CDB) containing 114 OPEs is presently established based on the suspect list from the current scientific literature. There are 12 established OPEs and a total of 83 emerging OPEs that have been reported in human and/or biota samples. Of the emerging OPEs more than 80% have nearly 100% detection frequencies in samples of certain environmental media including indoor air, wastewater treatment plants, sediment, and fish. In contrast to OPEs considered established contaminants, most emerging OPEs have been identified more recently due to the more pervasive use of high-resolution mass spectrometry (HRMS) based approaches and especially gas or liquid chromatography coupled with HRMS-based non-target analysis (NTA) of environmental sample fractions. Intentional/unintentional industrial use and non-industrial formation are sources of emerging OPEs in the environment. Predicted physical-chemical properties in silico of newer, molecularly larger and more oligomeric OPEs strongly suggest that some compounds such as bisphenol A diphenyl phosphate (BPA-DPP) are highly persistent, bioaccumulative and/or toxic. Limited information on laboratory-based toxicity data has shown that some emerging OPEs elicit harmful effects such as cytotoxicity, development toxicity, hepatotoxicity, and endocrine disruption in exposed humans and mammals. Established, and to a much lesser degree emerging OPEs, have also been shown to transform and degrade in biota and possibly alter their toxicological effects. Research on emerging OPE contaminants is presently limited and more study is warranted on sample analysis methods, source apportionment, transformation processes, environmental behavior, biomarkers of exposure and toxicity.

Simultaneous Determination of 147 Pesticide Residues in Traditional Chinese Medicines by GC-MS/MS

Determination of pesticide residues remains a challenge in traditional Chinese medicines in which complex compounds may interfere with analysis signals. This study reports the development of a simple, effective, and high-throughput method combining gas chromatography-tandem mass spectrometry (GC-MS/MS) with either QuEChERS or solid phase extraction (SPE) to determine 147 pesticide residues in traditional Chinese medicines simultaneously. In SPE, the mixture of n-hexane and ethyl acetate (1:1, v/v) was selected to extract 147 pesticides in honeysuckle, and the extracted pesticides were determined by GC-MS/MS. The limits of detection for all pesticides were within 0.01-0.05 mg/kg. The recoveries were within 70-120% and the relative standard deviations were below 20% for over 90% pesticides. The coefficients of determination were up to 0.999 for the linearity between MS signals and different concentrations of pesticides (20-200 ng/mL). The analytical performance was confirmed in determining pesticide residues in dried tangerine peel. SPE achieved comparable recoveries for all pesticides compared to the QuEChERS method.

Determination of Multi-pesticides Residues in Jasmine Flower and Its Scented Tea

For minor crops such as jasmine, the lack of pesticide registration and maximum residue limits are important issues that need to be solved in order to facilitate trading and ensure food safety. Meanwhile, reliable and quick analytical methods for multi-pesticide residues in these commodities are few, but required by various stakeholders. In this study, a method for detecting twenty-five most frequently used pesticides in jasmine flower and its scented tea by multi-plug filtration cleanup and ultra-high-performance liquid chromatography-tandem mass spectrometry was developed and validated. The cleanup process was optimized and compared with the dispersive solid phase extraction procedure. The method was validated, showing that except for methomyl, recoveries of twenty-five pesticides were 64%-108%, with relative standard deviations (n = 5) of 0.33%-10%. The method was successfully applied to detect pesticide residues in marketed samples. The results showed that some flower and tea samples contained a combination of different pesticide residues.

Simultaneous detection of ten kinds of insecticide residues in honey and pollen using UPLC-MS/MS with graphene and carbon nanotubes as adsorption and purification materials

An analytical method of simultaneous detection of ten insecticide residues in honey and pollen was established. The samples were purified with QuEChERS approach using new adsorbents and analyzed with UPLC-MS/MS. The results showed that both of graphene and carbon nanotubes were highly efficient adsorbents for the dSPE clean up to eliminate coextractives in the samples, and graphene was superior to carbon nanotubes for the detection of pesticide residues in honey and pollen samples. The proposed method was used to detect pesticide residues in 25 honey samples and 30 pollen samples which were randomly collected from more than ten provinces in China. All honey samples contain 1-27 μg/kg of chlorpyrifos residues. Only 4% of the honey samples were detected containing acetamiprid and imidacloprid, while the other seven pesticides were not detected. Chlorpyrifos residues were found in all pollen samples (5-66 μg/kg), among which twenty percent exceeded the maximum residue limits (MRLs, 50 μg/kg, European Commission Regulation). Most of the pollen samples containing pesticide concentrations higher than MRLs were collected from rape, followed by lotus, camellia, and rose. Besides, 36.7% and 33.3% of the pollen samples had imidacloprid and flupyradifurone higher than 5 μg/kg. A total of 26.7% pollen samples were detected containing bifenthrin, while none of the other six pesticides were detected in pollen samples.

Magnetic mesoporous material derived from MIL-88B modified by l-alanine as modified QuEChERS adsorbent for the determination of 6 pesticide residues in 4 vegetables by UPLC-MS/MS

More and more attention has been paid to the improved QuEChERS (quick, easy, cheap, effective, rugged and safe) method in dealing complex sample matrices, especially for the study of QuEChERS adsorbents. In this study, a magnetic mesoporous material, which was derived from MIL-88B modified by l-alanine, was synthesized as modified QuEChERS adsorbents for the simultaneous determination of multiple pesticides (Methomyl, Isoprocarb, Carbofuran, 3-Hydroxycarbofuran, Acetamiprid, Imidacloprid) in Chinese cabbage, celery, long bean and leek. The prepared magnetic adsorbents can effectively remove interfering substances from the sample, and the proposed modified QuEChERS method can reduce sample pretreatment time via an external magnetic field. To achieve the best performance of QuEChERS method, the clean-up time and amount of QuEChERS adsorbents were investigated. Under the optimized conditions, a simple, rapid and sensitive method for the determination of 6 pesticide residues in vegetables was established by coupling the modified QuEChERS to ultrahigh-performance liquid chromatography-tandem mass spectrometry. Excellent sensitivity (The limit of detection for the 6 pesticides ranged from 0.001 to 0.020 µg kg^-1), satisfactory linearity (r² ≥ 0.9952), good recovery (73.9-107.7%) and good precision (3.6-16.9% for intraday relative standard deviation, 0.5-15.0% for interday relative standard deviation) were obtained. Compared with traditional QuEChERS method, the proposed method is simple, cost-effective, and efficient, which indicates that the method can be used to detect carbamate and neonicotinoid pesticides in real samples and provide an excellent pretreatment technique for the detection of trace multi-analytes from complex substrates.

Detection of Pesticide Residues in Vegetables Sold in Changchun City, China

ABSTRACT

We evaluated fresh vegetables for residues of 18 pesticides with different chemical structures, including organochlorine pesticides, organophosphorus pesticides, carbamate pesticides, and pyrethroid pesticides and estimated that the potential health risks for consumers. A total of 313 samples were collected from 12 kinds of vegetables in Changchun, the capital of Jilin Province, People's Republic of China. Pesticide residues were analyzed by gas chromatography and mass spectrometry, and the curves were highly linear at 0.01 to 1.00 μg/mL (R2 ≥ 0.99). The mean recovery rate of the pesticides was 62 to 110% (relative standard deviation of <5%). The limit of detection was 0.0001 to 0.0167 mg/kg, the limit of quantification was 0.0002 to 0.0556 mg/kg, and the overall detection rate was 28.43%. The prevalence of pesticides and of samples above the standard limit were highest in celery, the prevalence of pesticides was lowest in potatoes, and the prevalence of samples above the standard limit was lowest in cucumber. Three of the 18 pesticides were not detected: omethoate, chlorpyrifos, and fenvalerate. Among the 15 pesticides detected, the maximum risk factor of six (carbofuran, omethoate, phorate, dicofol, dimethoate, and dichlorvos) is >1, indicating possible harm to human health. Residues of a single pesticide may not adversely affect a person's health, but multiple pesticide residues could present a health risk.

HIGHLIGHTS

Removal of Matrix Interferences by Nano-MgO and Co-Adsorbents for Accurate Multi-Pesticide Residue Analysis in the Chinese Medicinal Herb, Paeoniae Radix Alba

A simple, accurate, and high-throughput analytical method was developed to detect 123 pesticide residues in Chinese medicinal herb Paeoniae Radix Alba (PRA) by introducing nano-MgO as a highly efficient purification material based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) design concept. Various PRA samples were extracted using 8 mL 0.5% acetic acid-acetonitrile solution and purified by a dispersive solid-phase extraction method with 30 mg nano-MgO, 40 mg primary secondary amine (PSA), and 40 mg octadecylsilane (C18) as the cleanup adsorbents, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). 70.7% of pesticides showed a weak matrix effect after the purification process, indicating that this method can give the precise quantitative analysis of trace pesticides residue. The method was systematically validated under optimal conditions in five different kinds of PRA samples; good linearity was observed in the concentration range of 0.5-250 μg/L or 1-250 μg/L. Pesticide recovery in each sample spiked at concentrations of 20, 50, and 200 μg/kg ranged from 98.0% to 111% and the mean relative standard deviation ranged from 2.72% to 5.70%. Furthermore, the method comparison with the traditional QuEChERS method suggested the feasibility, advantages, and potential application prospect of the present method for the multi-pesticide residue analysis in various PRA samples.

Evaluation of clean-up procedures and sample dilution in multi-residue pesticide analysis of spices and herbs by UPLC-MS/MS

The matrix effect in complex spices and herbs presents a great challenge to the simultaneous, rapid, quantitative analysis of multiple pesticides by mass spectrometry. The aim of this work was to develop and validate an effective UPLC-MS/MS multi-residue method for the analysis of pesticide residues to reduce matrix effects in four spices and one herb and infer which component caused the matrix effect in black pepper. In this paper, we highlight the importance of reducing matrix effects. SPE and dilution factors combined with d-SPE were two approaches to reduce matrix effects compared with d-SPE, and dilution (5-fold) combined with d-SPE was more effective than SPE in reducing matrix effects. With the validated d-SPE method combined with dilution (5-fold), 22 pesticides showed satisfactory recovery (77 to 114%) and RSDs (1.4%-19.1%) at three spiked concentrations in dried chilli pepper, star anise, mint, and cinnamon skin, but not in black pepper. Compared to the other three spices and one herb, black pepper appeared to have a stronger matrix effect. D-SPE method combined with dilution (5-fold) was not suitable for black pepper and required more efficient purification methods and higher dilution factors. With the validated SPE method combined with 10-fold dilution, 19 pesticides showed satisfactory recovery (71% to 113%) and RSDs (2.1%-18.2%) at three spiked concentrations in black pepper. We ascertained that piperine was the component contributing most to the matrix effect in black pepper. The method was used to monitor 15 market samples.

Analytical methods to analyze pesticides and herbicides

This paper reviews studies published in 2019, in the area of analytical techniques for determination of pesticides and herbicides. It should be noted that some of the reports summarized in this review are not directly related to but could potentially be used for water environment studies. Based on different methods, the literatures are organized into six sections, namely extraction methods, electrochemical techniques, spectrophotometric techniques, chemiluminescence and fluorescence methods, chromatographic and mass spectrometric techniques, and biochemical assays. PRACTITIONER POINTS: Totally 141 research articles have been summarized. The review is divided into six parts. Chromatographic and mass spectrometric techniques are the most widely used methods.

Screening of multiclass pesticide residues in maca and Moringa oleifera by a modified QuEChERS sample preparation procedure and UPLC-ESI-MS/MS analysis

In the present study, a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was proposed for the simultaneous analysis of 75 pesticides in maca and Moringa oleifera with ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). The developed method was validated in accordance with linearity, linear range, limit of detection, limit of quantification, accuracy, precision, and matrix effect. Each analyte had good linearity (R² > 0.99) in the corresponding concentration range. The method LOD and LOQ values of all the analytes ranged from 0.01 μg kg⁻¹ to 303.35 μg kg⁻¹ and 0.03 μg kg⁻¹ to 1011.15 μg kg⁻¹, respectively. The recoveries (n = 6) of the analyzed pesticides were in the range of 75.92–113.43%. The RSDs of precision were between 0.60% and 7.36%. All matrix effect values ranged from 81.79% to 118.71% and 80.36% to 119.64% in maca and Moringa oleifera, respectively. The analysis of 103 samples showed the presence of isofenphos-methyl in some of them. The method had a good application prospect and could be used as a general approach for the quantitative determination of pesticide residues in food.

In the present study, a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was proposed for the simultaneous analysis of 75 pesticides in maca and Moringa oleifera with UPLC-ESI-MS/MS.

Pesticide residues determination in common bean using an optimized QuEChERS approach followed by solvent exchange and GC-MS/MS analysis

BACKGROUND

Common bean is a staple food in Latin America and Africa; however, studies about contamination of common bean with pesticides are rarely reported. So, the goals of this study were to validate a multiresidue method and apply it in monitoring of pesticides in common beans. Extraction was performed applying the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach to ground samples. Octadecylsilane and primary-secondary amine were used for clean-up, and a solvent exchange step was performed before injection for gas chromatography-tandem mass spectrometry analysis. Method validation was done analyzing blank samples spiked at 20, 30, 50, and 100 μg kg^-1 (n = 5). Linearity and linear range were assessed by the analysis of standard solutions at concentrations of 5, 15, 25, 50, 75, 100, and 150 μg L^-1 .

RESULTS

The method was successfully validated for 91 (64.1%) of the 142 compounds studied (139 pesticides and three degradation products). Limits of quantification were equal to 20 μg kg^-1 , 30 μg kg^-1 , 50 μg kg^-1 , and 100 μg kg^-1 for 18 (12.7%), 17 (12.0%), 21 (14.8%) and 35 (24.6%) compounds respectively. Fifteen (10.6%) compounds were not detected at any level, and 36 (25.4%) did not fulfill the requirements for a quantitative method. Sixteen common bean samples of South of Brazil were analyzed. Two samples were positive: one for tebuconzole and a second for picoxystrobin, permethrin, and cyproconazole. Cyproconazole is not allowed for use in the common bean crop, its use being a violation.

CONCLUSION

As demonstrated, the validated approach is suitable for pesticide residues determination in common bean. Results of the sample analysis show that the control of pesticide residues in common bean is necessary to ensure food safety. © 2020 Society of Chemical Industry.

Determination of pendimethalin in water, sediment, and Procambarus clarkii by high performance liquid chromatography-triple quadrupole mass spectrometry

We established a high-performance liquid chromatography-triple quadrupole mass spectrometry method for the analysis of pendimethalin residues in water, sediments, and Procambarus clarkii (Louisiana crayfish) tissues. Water samples were concentrated on a HLB solid-phase extraction column and eluted with dichloromethane and acetone (1:1). After drying under a stream of nitrogen gas, the sample volume was adjusted to 1 mL with the mobile phase solvent methanol/water/acetic acid (8:20:0.1). Pendimethalin was extracted with ethyl acetate containing 0.1% acetic acid, after rotary evaporation to dryness at 35 °C, the residue was dissolved in mobile phase solvent, purified by a neutral alumina column and graphitized carbon black powder (0.1 g). The mass characterization was conducted in positive ion mode, and the corresponding ions were detected in multi-reaction monitoring mode. The linear equations were y = 1 × 10⁶x + 14275, at pendimethalin levels of 0.05-20 μg L^-1 and y = 691029 × - 414368 for 20-200 μg L^-1. The detection limits of pendimethalin in water, sediments, and P. clarkii tissues were 1.0 × 10^-4μg L^-1 , 5.0 × 10^-3μg kg ^-1 and 5.0 × 10^-3 μg kg ^-1, respectively. The spiked recoveries ranged from 81.6 to 106.3%, and the relative standard deviations ranged from 4.58 to 13.6% (n = 6). The method provided an efficient and low-cost extraction and purification procedure that enabled a sensitive determination of pendimethalin in water as well as complex matrices.