Determination of Multiresidue Pesticides in Botanical Dietary Supplements Using Gas Chromatography-Triple-Quadrupole Mass Spectrometry (GC-MS/MS)

Simultaneous Screening and Quantification of 479 Pesticides in Green Tea by LC-QTOF-MS

A high-throughput screening and quantification method for 479 pesticides in green tea was established based on solid-phase extraction combined with liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Pesticides were extracted from samples using an optimized SPE (TPT cartridges) procedure. LC-QTOF-MS in All Ions MS/MS scan mode acquired full MS data for quantification and product ion spectra for identification. LC-QTOF-MS quantification was achieved using matrix-matched standard calibration curves to achieve the optimal method accuracy. The method performance characteristics included the linearity, overall recovery, precision, and measurement uncertainty being evaluated. The validation results exhibited a good sensitivity with the LOQs of 5-55 µg/kg, which was satisfactory for their MRLs in China or the EU. The recoveries of more than 92.7% of the 479 pesticides in green tea were 70-120% at the three spiked levels with a precision of ≤20%. Finally, this method was employed to analyze 479 pesticides in 95 tea samples from markets in China. The test results of the tea samples showed that tolfenpyrad, buprofezin, and pyridaben were found with lower concentrations. The method has effectively improved the determination efficiency of pesticide residue screening by high-resolution mass spectrometry in green tea.

Validation and interlaboratory comparison of anticoagulant rodenticide analysis in animal livers using ultra-performance liquid chromatography-mass spectrometry

Anticoagulant rodenticides (ARs) are used to control rodent populations. Poisoning of non-target species can occur by accidental consumption of commercial formulations used for rodent control. A robust method for determining ARs in animal tissues is important for animal postmortem diagnostic and forensic purposes. We evaluated an ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS) method to quantify 8 ARs (brodifacoum, bromadiolone, chlorophacinone, coumachlor, dicoumarol, difethialone, diphacinone, warfarin) in a wide range of animal (bovine, canine, chicken, equine, porcine) liver samples, including incurred samples. We further evaluated UPLC-MS in 2 interlaboratory comparison (ILC) studies; one an ILC exercise (ICE), the other a proficiency test (PT). The limits of detection of UPLC-MS were 0.3-3.1 ng/g, and the limits of quantification were 0.8-9.4 ng/g. The recoveries obtained using UPLC-MS were 90-115%, and relative SDs were 1.2-13% for each of the 8 ARs for the 50, 500, and 2,000 ng/g spiked liver samples. The overall accuracy from the laboratories participating in the 2 ILC studies (4 and 11 laboratories for ICE and PT studies, respectively) were 86-118%, with relative repeatability SDs of 3.7-11%, relative reproducibility SDs of 7.8-31.2%, and Horwitz ratio values of 0.5-1.5. Via the ILC studies, we verified the accuracy of UPLC-MS for AR analysis in liver matrices and demonstrated that ILC can be utilized to evaluate performance characteristics of analytical methods.

Dietary Supplements with Proline-A Comprehensive Assessment of Their Quality

Dietary supplements are food products commonly used worldwide to obtain nutritional and physiological effects. They can contain a wide variety of active substances and can be administered for health and disease. Their use can be beneficial if justified, and their quality is adequate. Unfortunately, data on the quality of supplements is scarce. As part of this work, we assess the quality of seven dietary supplements containing proline. The preparations were produced in the EU and the USA. The quality assessment consisted of the detection of potential impurities, the determination of the content of the main ingredient, and the release of proline. The technique used to analyse impurities and proline (Pro) content was liquid chromatography coupled with tandem mass spectrometry. We detected five contaminants. The main ingredient content was in the range of 73-121% in capsules and 103-156% in tablets. Five of the seven analysed dietary supplements released below 80% Pro (for each tablet/capsule at pH 1.2). One of the supplements may be inactive because a very low release of Pro was reported. The results, we hope, will increase consumer awareness of the quality of these preparations and result in a change in the regulations governing the marketing of these preparations, at least by making release testing mandatory.

Application of Liquid Chromatography Coupled to Mass Spectrometry in Quality Assessment of Dietary Supplements—A Case Study of Tryptophan Supplements: Release Assay, Targeted and Untargeted Studies

Dietary supplements are widely consumed in the EU and the USA. Based on their similarity to pharmaceuticals, consumers mistakenly believe that dietary supplements have also been approved for safety and efficacy. However, in the absence of mandatory testing, data on supplement quality is scarce. Thus, we applied liquid chromatography coupled with tandem mass spectrometry to analyse the quality of dietary supplements containing tryptophan (Trp). We examined 22 supplements in tablets or capsules, produced in the USA, Great Britain, Germany, France, Czech Republic, and Poland. Trp release, crucial for bioavailability and efficiency, was assessed. Additionally, we performed a qualitative analysis of the main ingredient and screened for contaminants. Among the contaminants, we detected Trp’s metabolites, condensation products of Trp and carbonyl compounds, Trp degradation products, degradation products of kynurenine, and other contaminants such as glucosamine and melatonin. The main ingredient content was in the range of 55–100% in capsules and 69–87% in tablets. Surprisingly, almost no Trp release was noted from some supplements. Our study confirms the need to advance research on supplements. We believe that the high-quality analysis of supplements based on reliable analytical techniques will be an important contribution to the discussion on the regulatory framework of these products.

Analysis of dietary exposure and risk assessment of pesticide residues in roots and rhizomes of Chinese herbs

Medicine food homologous (MFH) plants provide therapeutic and health care effects through diet. Thus, a risk assessment system for hazardous ingredient residues is urgently required to ensure their safe use. In this study, the pesticide contamination of six root and rhizome Chinese herbs, Ginseng Radix et Rhizoma, Panacis Quinquefolii Radix, Pseudostellariae Radix, Salviae Miltiorrhizae Radix et Rhizoma, Codonopsis Radix, and Glehniae Radix, and the risks associated with their intake were investigated. A total of 420 MFH plant samples collected from 22 provinces in China were tested, and 61 pesticides were detected in 413 samples. Multiple pesticide residues were detected in each MFH sample, with contents ranging from 0.0002 to 3.010 mg/kg dry weight. Carbendazim (≥47.14%) and propham (≥40%) were the most frequently detected pesticides. Risk assessment determined by hazard quotients indicated that the risks were acceptable, with no short- or long-term adverse health effects. However, considering the high incidence of residues and the detection of unregistered or even prohibited pesticides, strict supervision of soil quality and pesticide application (particularly cadusafos) in MFH plant cultivation are recommended to aid in monitoring MFH plant quality and ensuring diet and drug safety. PRACTICAL APPLICATION: Ensure the diet and drug safety of Chinese herbs.

The Effect of Mycotoxins and Silymarin on Liver Lipidome of Mice with Non-Alcoholic Fatty Liver Disease

Milk thistle-based dietary supplements have become increasingly popular. The extract from milk thistle (Silybum marianum) is often used for the treatment of liver diseases because of the presence of its active component, silymarin. However, the co-occurrence of toxic mycotoxins in these preparations is quite frequent as well. The objective of this study was to investigate the changes in composition of liver lipidome and other clinical characteristics of experimental mice fed by a high-fat methionine-choline deficient diet inducing non-alcoholic fatty liver disease. The mice were exposed to (i) silymarin, (ii) mycotoxins (trichothecenes, enniatins, beauvericin, and altertoxins) and (iii) both silymarin and mycotoxins, and results were compared to the controls. The liver tissue extracts were analyzed by ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry. Using tools of univariate and multivariate statistical analysis, we were able to identify 48 lipid species from the classes of diacylglycerols, triacylglycerols, free fatty acids, fatty acid esters of hydroxy fatty acids and phospholipids clearly reflecting the dysregulation of lipid metabolism upon exposure to mycotoxin and/or silymarin.

Facile synthesis of an aggregation-induced emission (AIE) active imidazoles for sensitive detection of trifluralin

A novel imidazoles fluorescent probe (2) was synthesized from vanillin, o-phenylenediamine, and N,N-diphenylcarbamyl chloride. Its structure was characterized by fluorescence spectra, UV-Vis spectra, ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry (HRMS). Moreover, its aggregation-induced emission (AIE) feature was investigated in THF/MeOH solution. Furthermore, the fluorescence quenching experimental results suggest that compound 2 is the potential fluorescent probe of small organic molecules showing high selectivity and sensitivity for nitroaromatic compounds. In addition, the probe could be applied in the determination of trifluralin with fast response and stability. The fluorescence response of the probe exhibited a good linear correlation with the concentration of trifluralin ranging from 10 to 100 μM, and the limit of detection (LOD) was as low as 5.066 μM. Finally, the probe was successfully utilized to determine the amount of trifluralin in real samples, and the recoveries were 91.1% to 111.2%, indicating the applicability and reliability of the probe.

[Rapid screening and confirmation of 415 pesticide residues in red cabbages by liquid chromatography-quadrupole-time of flight-mass spectrometry]

An analytical method for the simultaneous rapid screening and accurate confirmation of 415 pesticide residues in red cabbages was established using liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-QTOF/MS) with single acquisition. In the established method, the pesticides in red cabbage were extracted using acetonitrile-acetic acid (99∶1, v/v) and salted-out using anhydrous magnesium sulfate and sodium chloride. The resultant solution was then cleaned-up by automatic solid phase extraction using a Carbon/NH2 cartridge. The SPE cartridge was activated with 4 mL acetonitrile-toluene (3∶1, v/v) and the effluents were discarded. The resultant solution was transferred to the Carbon/NH2 cartridge, using 3×2 mL acetonitrile-toluene (3∶1, v/v) to wash the test sample concentrate bottle, and waited until the surface of the test sample concentrate liquid reached the top layer of anhydrous Na2SO4 before transferring the washing liquid to the cartridge. A 30-mL reservoir was attached to the upper part of the SPE cartridge and 25 mL acetonitrile-toluene (3∶1, v/v) was used to wash the SPE cartridge again. The eluent was evaporated in the glass tube in a water bath at 37 ℃ and shaking speed 150 r/min to reduce the volume to 0.5 mL. Nitrogen was used to dry the concentrates, and the residues were dissolved in 1.0 mL acetonitrile-water (3∶2, v/v), homogenized by ultrasonication, and passed through 0.22-μm filtering membrane before determination. The dissolved sample solution was loaded onto a ZORBAX SB-C18 column (100 mm×2.1 mm, 3.5 μm) and separated under gradient elution using 0.1% (v/v) formic acid aqueous solution containing 5 mmol/L ammonium acetate and acetonitrile as the binary mobile phase. The eluent from the column was further detected by QTOF/MS under electrospray positive ionization in the MS/MS scanning mode. A matrix-matched external calibration method was used for quantitation. By optimizing the different parameters under Auto MS/MS and All Ions MS/MS acquisition modes, the optimal conditions for All Ions MS/MS under each acquisition mode were obtained, which were then compared for selection of a better mode. The results demonstrated that the developed method can be used to accurately screen and quantify all 415 pesticides in red cabbage. The linear regression correlation coefficients (r2) for the 415 pesticides were all greater than 0.990 in the corresponding linear concentration range. In addition, the screening detection limits (SDL) of 411 pesticides were no more than 5 μg/kg, and the limits of quantification (LOQs) of 413 pesticides were no more than 10 μg/kg. At the spiked levels of LOQ, two-fold LOQ, and 10-fold LOQ, the recoveries were in the ranges of 65.7%-118.4%, 72.0%-118.8% and 70.2%-111.2%, with relative standard deviations (RSDs) in the ranges of 0.9%-19.7%, 0.2%-19.9% and 0.6%-19.9%, respectively. The method was applied to detect pesticide residues in the red cabbage samples provided by the 2019 European proficiency test project for unknown pesticide screening (EUPT-SM-11) and accurate quantitation (EUPT-FV-21). For EUPT-SM-11, all the spiked and incurred pesticides in red cabbage were qualified accurately, without false positives or false negatives. This is completely consistent with the final results published by the EU official. For EUPT-FV-21, there were 19 non-volatile pesticides that can be detected by LC-MS, which were then accurately quantitated with the corresponding pesticide standard. The results demonstrate that the proposed method is accurate and reliable. It is also rapid and time-saving, and can be used for high-throughput screening and quantitative determination of pesticide residues in cabbage. It can also be extended to other fruits and vegetable matrices.

Recent advances in metal-organic frameworks for pesticide detection and adsorption

The large-scale use of pesticides such as organophosphate pesticides (OPPs) and organochlorine pesticides (OCPs) has led to serious environmental problems worldwide, and their high toxicity could cause serious damage to human health. It is crucial to remove and track them precisely in the environment and food resources. As novel nanomaterials, metal-organic frameworks (MOFs) have attracted significant attention in the fields of adsorption and luminescence sensing due to their rich topology, tunable pore size and shape, high surface area, and abundant active sites. Luminescent metal-organic frameworks (LMOFs) have sprung up as great potential chemical sensors to detect pesticides with fast response, high sensitivity, high selectivity and easy operation. Therefore, in this highlight, we focus on recent progress of MOFs in sensing and adsorbing pesticides, as well as in the possible mechanism of sensing, so as to attract more attention to pesticide detection and adsorption.

Quantification of persistent organic pollutants in dietary supplements using stir bar sorptive extraction coupled with GC-MS/MS and isotope dilution mass spectrometry

In this work, we describe a method developed to quantify persistent organic pollutants (POPs) including polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in dietary supplement samples using stir-bar sorptive extraction (SBSE)-GC-MS/MS-isotope dilution mass spectrometry (IDMS). This method enables accurate, precise, and sensitive quantification of POPs in plant-extract based dietary supplement products commercially available in the United States. When compared with calibration curves, IDMS provided more accurate and precise measurements. The mean error of measurements using this method was 7.24% with a mean RSD of 8.26%. The application of GC-MS/MS enabled approximately two-order-of-magnitude lower limit of quantifications compared with GC-MS. 12 commercially available plant-extract based dietary supplement samples were analysed using this method. PAHs including naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo[a]pyrene were detected in most of the products and had average concentrations over 1 ng/g. OCPs were detected less frequently than PAHs in these products, and none of the OCPs had mean concentrations over 1 ng/g. The mean toxin concentration of each product was calculated, and the highest value was 3.20 ng/g. These results were compared with existing guidelines and none of the analytes in the samples were found to be above the daily allowable limits.

Contaminants: a dark side of food supplements?

Food supplements (FS) are often consumed as one of the strategies to fight ageing-associated pathologies, especially in the case of oxidative stress-related diseases. Despite the popularity of FS, some concerns about their quality and safety have been raised, especially regarding the presence of contaminants. This paper reviews and discusses the occurrence of contaminants in marketed samples of FS in the last two decades, considering both scientific literature and notifications registered on RASFF portal. The most relevant classes of contaminants were included namely metals, toxins, pesticides, dioxins and PCBs, as well as pharmacologically active ingredients. Variable amounts of contaminants were reported in a significant number of commercially available FS. Although the presence of contaminants does not necessarily mean that their levels exceed the regulatory limits or that the FS intake constitutes a risk to human health, it alerts for the need to further monitor FS safety. The evaluation of the risk associated to the consumption of FS, especially in the elderly population, is particularly challenging due to the frequent exposure to multiple toxicants and to different exposure sources, as well as due to possible pre-existing diseases and respective therapeutics. Therefore, improved quality control procedures and monitoring programs should be pursued in order to avoid undesirable products and assure the safety of FS.

Investigation of the Presence of 22 Organochlorine Pesticide Residues in Ginseng from Jilin Province, China

The purpose of this study was to investigate the status of organochlorine pesticide residues in 186 ginseng samples collected in Jilin, People's Republic of China. Based on the Chinese Pharmacopoeia 2015 method for detection of organochlorine pesticide residues in ginseng, 22 organochlorine pesticide residues were identified. Chlordane, aldrin, epichlorohydrin, and dieldrin and their isomers were not detected in ginseng from this region. Heptachlor was detected in only one ginseng sample, and the concentration did not exceed the maximum residual limit (MRL) prescribed in the Pharmacopoeia (0.05 mg/kg). Benzene hexachloride was detected in two samples, one of which was above the MRL. Hexachlorobenzene and pentachloronitrobenzene (quintozene) were found in 11.8 and 52.1% of the samples, respectively, and the residues in these samples exceeded the MRL by 4.3 and 8.6%, respectively.

Poor chemical and microbiological quality of the commercial milk thistle-based dietary supplements may account for their reported unsatisfactory and non-reproducible clinical outcomes

Herbal-based dietary supplements have become increasingly popular. The extract from milk thistle (Silybum marianum), is often used for the treatment of liver diseases. However, serious concerns exist regarding the efficacy, composition, as well as the safety of these over-the-counter preparations. Therefore, the aim of the present study was to investigate the composition as well as chemical and biological safety of 26 milk thistle-based dietary supplements purchased from both the U.S. and Czech markets between 2016 and 2017. The study was focused on a determination of the composition of active ingredients, as well as analyses of possible contaminants including: mycotoxins, plant alkaloids, and pesticide residues, as well as the microbial purity. High-throughput analyses were performed using advanced U-HPLC-HRMS techniques. Large differences in the silymarin content were observed among individual milk thistle preparations, often in contrast with the information provided by the manufacturers. In addition, substantial inter-batch differences in silymarin content were also demonstrated. In all milk thistle preparations tested, large numbers and high concentrations of mycotoxins and several pesticides, as well as the substantial presence of microbiological contamination were detected, pointing to serious safety issues. In conclusion, our results strongly indicate the need for strict controls of the composition, chemical contaminants, as well as the microbiological purity of commercial milk thistle extracts used for the treatment of liver diseases. Poor definition of these preparations together with contamination by biologically active substances may not only account for the inconsistency of clinical observations, but also be responsible for possible herbal-based dietary supplements-induced liver injury.

Recent Advances and Perspectives of Molecularly Imprinted Polymer-Based Fluorescent Sensors in Food and Environment Analysis

Molecular imprinting technology (MIT), also known as molecular template technology, is a new technology involving material chemistry, polymer chemistry, biochemistry, and other multi-disciplinary approaches. This technology is used to realize the unique recognition ability of three-dimensional crosslinked polymers, called the molecularly imprinted polymers (MIPs). MIPs demonstrate a wide range of applicability, good plasticity, stability, and high selectivity, and their internal recognition sites can be selectively combined with template molecules to achieve selective recognition. A molecularly imprinted fluorescence sensor (MIFs) incorporates fluorescent materials (fluorescein or fluorescent nanoparticles) into a molecularly imprinted polymer synthesis system and transforms the binding sites between target molecules and molecularly imprinted materials into readable fluorescence signals. This sensor demonstrates the advantages of high sensitivity and selectivity of fluorescence detection. Molecularly imprinted materials demonstrate considerable research significance and broad application prospects. They are a research hotspot in the field of food and environment safety sensing analysis. In this study, the progress in the construction and application of MIFs was reviewed with emphasis on the preparation principle, detection methods, and molecular recognition mechanism. The applications of MIFs in food and environment safety detection in recent years were summarized, and the research trends and development prospects of MIFs were discussed.

Selective sensing and visualization of pesticides by ABW-type metal–organic framework based luminescent sensors

A new ABW-type luminescent metal–organic framework (MOF) namely (H₃O)[Zn₂L(H₂O)]·3NMP·6H₂O (1), constructed with eco-friendly Zn²⁺ and the multicarboxylate intraligand (LH₅) was designed, synthesized and fully characterized by X-ray single-crystal diffraction, steady-state absorption and emission spectroscopy, and SEM observations. The MOF-based suspension sensor 1 (NMP) demonstrated high sensitivity to low-concentration pesticides of chlorothalonil (CTL), nitrofen (NF), trifluralin (TFL), and 2,6-dichloro-4-nitroaniline (DCN), which was assigned to the synergistic effect of the photoinduced electron transfer and the fluorescence resonance energy transfer. With the highest luminescent detection efficiency (K_SV up to 11.194 μmol⁻¹ and LOD down to 2.93 ppm) to DCN, 1 (NMP) was successfully applied for the selective sensing of DCN. The MOF-based film sensor 1 (film) illustrated the selective visualization sensing of trace amounts of DCN. In addition, based on the high saturated vapor pressure of TFL and the unique bathochromic shift effect to the emission maxima of 1, the MOF-based luminescent vapor sensing device 1 (LED) successfully exhibited operability for sensing of TFL vapor. The results illustrated a feasible approach to construct new MOF-based luminescent sensors for selective sensing and visualization of pesticides.

A novel ABW-type luminescent metal–organic framework was applied for selective visualization sensing of trace amounts of 2,6-dichloro-4-nitroaniline and vapor sensing of trifluralin.

Occurrence and distribution of pesticides in precipitation as revealed by targeted screening through GC-MS/MS

Facing the tough challenge of precise measurement of ever-increasing numbers of organic contaminants in the environment, there is an urgent need for more reliable and cost-effective methodologies. In this study, we developed and validated a screening method for analysis of over 450 pesticides in precipitation using gas chromatography with tandem mass spectrometry (GC-MS/MS) in multiple reaction monitoring (MRM) mode. Solid phase extraction (SPE) was applied to extract target analytes from precipitation. Using this targeted approach, we managed to detect 123 pesticides with maximum retention time shifts below 0.1 min (except for DEET) in 101 precipitation samples collected between October 2015 and March 2017 in Singapore. This is probably the first study to report the measurements of a wide range of pesticides in precipitation. A spectrum of insecticides, herbicides, fungicides and their synergists were detected and among them DEET, malathion and carbaryl were the most frequently detected pesticides (detection frequency: 100%, 96% & 67%). The Spearman correlations suggest that some pesticides of different subgroups had significant correlations. It is believed that these finding could shed light on the understanding of the contribution of precipitation to environmental contaminants in water cycle.

Pressurized Solvent Extraction with Ethyl Acetate and Liquid Chromatography-Tandem Mass Spectrometry for the Analysis of Selected Conazole Fungicides in Matcha

The extraction of powdered nutraceuticals is challenging due to the low water content and high concentration of matrix components that can lead to significant matrix effects in liquid chromatography-positive ion electrospray ionization-tandem mass spectrometry (LC-ESI⁺-MS/MS). In this study we assess the feasibility of using pressurized solvent extraction with ethyl acetate to reduce the co-extraction of polar matrix components. Pigment attributed to chlorophyll was removed with in-cell clean-up utilizing Anasorb 747, Florisil^®, and C18. Visible inspection of the extracts showed that pigment was removed from matcha, a powdered green tea sample. Pressurized solvent extraction with in-cell clean-up can be utilized to remove pigments from powdered samples such as nutraceuticals. Average matrix effect of the 32 target analytes that observed mass spectrometric signal suppression or soft MS signal enhancement was -41 ± 19% with the majority of analytes having a protonated molecular ion with m/z of 250 to 412. As generally moderate signal suppression was observed for conazole fungicides and structurally related compounds analyzed by LC-ESI⁺-MS/MS, it is recommended that matrix matched or standard addition calibration is used for quantitation. Catachins, other polyphenols, and caffeine are expected to contribute to the matrix effects observed in LC-ESI⁺-MS/MS. Diniconazole, fenbuconazole, and tebufenozide were the only target analytes with severe MS signal enhancement. Low levels (0.002⁻0.004 mg/kg) of prothioconazole-desthio and flusilazole were detected, along with trace levels of tebuthiuron in matcha.

Rapid and Simultaneous Analysis of 360 Pesticides in Brown Rice, Spinach, Orange, and Potato Using Microbore GC-MS/MS

A multiresidue method for the simultaneous and rapid analysis of 360 pesticides in representative agricultural produce (brown rice, orange, spinach, and potato) was developed using a modified QuEChERS procedure combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). Selected reaction monitoring transition parameters (e.g., collision energy, precursor and product ions) in MS/MS were optimized to achieve the best selectivity and sensitivity for a wide range of GC-amenable pesticides. A short (20 m) microbore (0.18 mm i.d.) column resulted in better signal-to-noise ratio with reduced analysis time than a conventional narrowbore column (30 m × 0.25 mm i.d.). The priming injection dramatically increased peak areas by masking effect on a new GC liner. The limit of quantitation was <0.01 mg/kg, and the correlation coefficients (r²) of matrix-matched standards were >0.99 within the range of 0.0025-0.1 mg/kg. Acetonitrile with 0.1% formic acid without additional buffer salts was used for pesticide extraction, whereas only primary-secondary amine (PSA) was used for dispersive solid phase extraction (dSPE) cleanup, to achieve good recoveries for most of the target analytes. The recoveries ranged from 70 to 120% with relative standard deviations of ≤20% at 0.01 and 0.05 mg/kg spiking levels (n = 6) in all samples, indicating acceptable accuracy and precision of the method. Seventeen real samples from local markets were analyzed by using the optimized method, and 14 pesticides in 11 incurred samples were found at below the maximum residue limits.