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An analysis method for simultaneous determination of 46 kinds of fungicides and insecticides residues in tomatoes by QuEChERS method combined with gas chromatography-mass spectrometry was established. The samples were extracted with acetonitrile, then purified up with PSA, C18 and anhydrous MgSO4, separated by a HP-5MS chromatographic column, analyzed using multiple reflection monitoring (MRM) mode, and quantified by matrix-matched external standard method. The result showed that, the 46 kinds of pesticides showed good linearity when they were in 0.005～0.500 μg/mL (R2>0.999). The limits of detection of the 46 kinds of pesticides were in 0.07～2.63 μg/kg, and the limits of quantitation were in 0.21～8.39 μg/kg. The average recoveries were 70.40%～115.08% with the relative standard deviations of 0.22%～4.89% at the spiked levels of 0.0025, 0.025 and 0.25 mg/kg. Residues of chlorpyrifos and azoxystrobin were detected in 9 of the 50 batches of tomato samples, with the content ranging from 0.0043～0.0365 mg/kg, which did not exceed the limit value specified in GB 2763-2021. The method was rapid, simple, sensitive and accurate, which could meet the detection of multiple pesticide residues in tomato.

Introduction: Ayahuasca is a psychoactive drink originally consumed by indigenous people of the Amazon. The lack of regulation of this drink leads to uncontrolled consumption, and it is often consumed in religious contexts., Objective: The aim of this work is to compare three miniaturised extraction techniques for extracting the main ayahuasca compounds from beverages., Methodology: Three sample pretreatment techniques were evaluated (dispersive liquid-liquid microextraction [DLLME], microextraction by packed sorbent [MEPS] and QuEChERS [Quick, Easy, Cheap, Effective, Rugged and Safe]) for the simultaneous extraction of N,N-dimethyltryptamine (DMT), tetrahydroharmine (THH), harmine, harmaline, harmol and harmalol from ayahuasca beverage samples. Then, the most promising technique (QuEChERS) was chosen to pre-concentrate the analytes, subsequently detected by high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD)., Results: The procedure was optimised, with the final conditions being 500 μL of extractor solvent, 85 mg of primary secondary amine (PSA) and 4 s of vortexing. The analytical method was validated, showing to be linear between 0.16 and 10 μg/mL for β-carbolines and between 0.016 and 1 μg/mL for DMT, with coefficients of determination (R 2 ) between 0.9968 and 0.9993. The limit of detection (LOD) and lower limit of quantification (LLOQ) were 0.16 μg/mL for all compounds, except for DMT (0.016 μg/mL) and extraction efficiencies varied between 60.2% and 88.0%., Conclusion: The analytical methodology proved to be accurate and precise, with good linearity, LODs and LLOQs. This method has been fully validated and successfully applied to ayahuasca beverage samples., (© 2024 The Authors. Phytochemical Analysis published by John Wiley & Sons Ltd.)

A method utilizing high-performance liquid chromatography-fluorescence detection (HPLC–FLD) has been developed and refined for the simultaneous detection of florfenicol (FF) and its metabolite florfenicol amine (FFA) along with three fluoroquinolone (ciprofloxacin (CIP), enrofloxacin (ENR), and sarafloxacin (SAR)) residues in different parts of eggs (whole egg, egg yolk, and egg albumen). The QuEChERS (“Quick, easy, cheap, effective, rugged, and safe”) procedure utilized 0.1 M disodium EDTA solution, water, and acetonitrile as extractants; sodium sulfate, sodium chloride, and trisodium citrate as dehydrating salts; and N-propylethylenediamine and C18 as adsorbents. A dual-channel FLD method was utilized to analyze the target compounds using an XBridge BEH C18 chromatographic column (4.6 mm × 150 mm, 5 μm). The mobile phase was employed isocratically using a solution of 0.01 M sodium dihydrogen phosphate, 0.005 M sodium dodecyl sulfate, and 0.1% triethylamine (pH 4.8) in combination with acetonitrile at a ratio of 65:35 (V/V). The limits of detection (LOD) and quantification (LOQ) of the analytes ranged from 0.03 to 1.5 µg/kg and from 0.1 to 5.0 µg/kg, respectively. The recoveries of the analytes in the blank egg samples ranged from 71.9% to 94.8% when reference standard concentrations of the LOQ, half of the maximum residual limit (MRL), MRL, and twice the MRL were added. The parameters of the presented protocol were validated and subsequently applied to the analysis of real samples, demonstrating the applicability and reliability of the method.

Objective: To achieve rapid, quantitative and high-throughput detection of aminoglycoside antibiotic residues in pork. Methods: Square-array aligned SERS substrates based on Au nanoflowers （AuNFs） were prepared using PP synthetic paper as a substrate. Pork samples were pre-treated by QuEChERs method and subjected to SRES. Results: Using 4-mercaptobenzoic acid as the SERS probe molecule, the substrate exhibited good homogeneity, SERS enhancement effect, reproducibility and stability. the SERS signal intensities at the characteristic peaks at 475, 619 cm-1 showed good linear relationships with the logarithms of the concentrations of gentamicin sulphate and neomycin sulphate, respectively （R2 of 0.991 6 and 0.990 7, respectively）. The limits of detections （LODs） were as low as 1×10-9, 1×10-8 mol/L, respectively, and were successfully applied to the rapid, quantitative and high-throughput determination of aminoglycoside antibiotics in pork. Conclusion: The experimental method provides an economical, efficient, time-saving and highly sensitive way for the application of SERS technology for the detection of antibiotic residues in real meat samples.

Recently, hexahydrocannabinol (HHC) was posed under strict control in Europe due to the increasing HHC-containing material seizures. The lack of analytical methods in clinical laboratories to detect HHC and its metabolites in biological matrices may result in related intoxication underreporting. We developed and validated a comprehensive GC-MS/MS method to quantify 9(R)-HHC, 9(S)-HHC, 9αOH-HHC, 9βOH-HHC, 8(R)OH-9(R)-HHC, 8(S)OH-9(S)HHC, 11OH-9(R)HHC, 11OH-9(S)HHC, 11nor-carboxy-9(R)-HHC, and 11nor-carboxy-9(S)-HHC in whole blood, urine, and oral fluid. A novel QuEChERS extraction protocol was optimized selecting the best extraction conditions suitable for all the three matrices. Urine and blood were incubated with β-glucuronidase at 60 °C for 2 h. QuEChERS extraction was developed assessing different ratios of Na2SO4:NaCl (4:1, 2:1, 1:1, w/w) to be added to 200 µL of any matrix added with acetonitrile. The chromatographic separation was achieved on a 7890B GC with an HP-5ms column, (30 m, 0.25 mm × 0.25 µm) in 12.50 min. The analytes were detected with a triple-quadrupole mass spectrometer in the MRM mode. The method was fully validated following OSAC guidelines. The method showed good validation parameters in all the matrices. The method was applied to ten real samples of whole blood (n = 4), urine (n = 3), and oral fluid (n = 3). 9(R)-HHC was the prevalent epimer in all the samples (9(R)/9(S) = 2.26). As reported, hydroxylated metabolites are proposed as urinary biomarkers, while carboxylated metabolites are hematic biomarkers. Furthermore, 8(R)OH-9(R)HHC was confirmed as the most abundant metabolite in all urine samples. [ABSTRACT FROM AUTHOR]

Background: Maternal fluids play a key role in the risk assessment regarding early life pesticide exposure as the chemicals can transfer to neonate through prenatal exposure and lactation. Aim: A developed UHPLC-DAD and modified QuChERS methods were validated for human serum and breast milk. Matrix effect of the biological samples were evaluated. Methods & results: Serum was extracted by unbuffered QuChERS method while breast milk was extracted by citrate buffered method with addition of hexane. Remaining lipid in breast milk extract was later removed using lipid-removal sorbent. Sample matrices caused huge impacted on low-sensitivity pesticides. Conclusion: The modified QuEChERS methods coupled with UHPLC-DAD were fully validated. Application in paired-serum and breast milk samples revealed 6 detected pesticides.

This study aimed to develop and validate a multi-mycotoxin analysis method applied to cashew nuts by employing a miniaturized QuEChERS method followed by determination by ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Satisfactory recoveries for the concentrations 1, 10 and 30 ng g -1 , ranging from 66% (fumonisin B 1 ) to 110% (ochratoxin A) and relative standard deviations lower than 9% (fumonisin B 2 ) were obtained for the target compounds. Limits of quantification ranged from 0.004 ng g -1 (sterigmatocystin) to 0.59 ng g -1 (alternariol). The applicability of the analytical method was verified by analyzing 30 cashew nut samples from the city of Rio de Janeiro, RJ, southeastern Brazil. Aflatoxins M1, G2, G1, B2, B1, ochratoxin A and sterigmatocystin were detected, respectively, in 27%, 10%, 17%, 30%, 30%, 30% and 50% of the analyzed samples, at maximum concentrations of 0.56, 0.67, 1.43, 2.02, 4.93, 4.81, and 0.35 ng g -1 . The maximum limit established by Brazilian legislation for aflatoxins was not exceeded by any of the analyzed samples.

A UHPLC-MS/MS analysis method was established for simultaneous determination of 8 plant growth regulators (PGRs) residues in citrus and unhusked rice. The QuEChERS technique was used for extracting and purifying the target sub- stances from the samples, with MRM monitoring mode and the quantification was carried out using a matrix-matched working curve external standard method. Under the optimized conditions, good linearity was achieved for the 8 PGRs in the linear range, including Chlormequat chloride Uniconazole Forchlorfenuron Ethychlozate Diethyl aminoethyl hexanoate Indole-3-butyric Acid, Thidiazuron 2,4-D, the linear correlation coefficients are all more than 0.995, with recovery ranging from 70.1% to 105.6% with the RSD below 10.8% (n=6). The sample matrix type and sensitivity are better than or equivalent to the existing national testing standards and this method has been successfully applied to the detection of plant growth regulator residues in citrus fruits and unhusked rice samples. The above results show that the method is accurate and sensitive, and can be used for qualitative and quantitative analysis of plant growth regulators residues in citrus fruits and unhusked rice. [ABSTRACT FROM AUTHOR]

ObjectiveA qualitative and quantitative method was established for the simultaneous detection of 60 mycotoxins in nuts and dried fruits.MethodsPeanuts and raisins， two typical food substrates rich in fat and sugar， were pre-processed by QuEChERS technique （900 mg MgSO4， 150 mg PSA， 150 mg C18）， and analyzed by ultra-high performance liquid chromatography-high resolution mass spectrometry （UPLC-Orbitrap/MS） with full scan and data-dependent scanning （dd-MS2） mode. It was qualitatively determined by the retention time and accurate mass of mycotoxins， the chromatographic peak area was quantified， and the fragment ion information was used for confirmation.ResultsThe results showed that the pH value of the extraction solution significantly affected the dissociation state of mycotoxins， which in turn affected the recovery rate. The interference of components such as carbohydrates and lipids in the sample was effectively removed by QuEChERS purification， and the accuracy of qualitative and quantitative analysis was improved. A blank matrix-matched standard curve was used for calibration to reduce the matrix effect and meet the quantitative analysis requirements. The mycotoxins had a good linear relationship within their respective mass concentration ranges （correlation coefficient R2>0.95）， and the recoveries were 60%-120% with relative standard deviation less than 20%. The other seven mycotoxins with R2 less than 0.95 can be qualitatively analyzed.ConclusionCompared with the detection method based on triple quadrupole mass spectrometry， the high-resolution mass spectrometry method is easier to quantify， and there is no need to optimize the parent ion， product ion and collision energy for the target one by one，which can effectively reduce the difficulty and time consuming for multi-target analysis. The method has high sensitivity， accuracy and reliable results， and is suitable for the qualitative and quantitative analysis of 60 mycotoxins in nuts and dried fruits.

Abstract Background The quick, easy, cheap, effective, rugged, and safe (QuEChERS) method can be employed for multi-residue analyses instead of traditional extraction methods due to its advantages in terms of extraction time and required equipment. A modified version of the QuEChERS method has been developed for quantifying eight pharmaceuticals belonging to different classes in three real soils with different chemical properties. Firstly, the soils have been polluted with all contaminants and the recoveries were determined by liquid chromatography tandem–mass spectrometry. Due to similar recoveries from the three soils, the validation of the method has been carried out only on a soil by determining linearity, recovery, precision, limit of detection (LOD) and limit of quantification (LOQ) values. A matrix-matched calibration for the soil has been adopted in order to avoid the matrix effect and three levels of fortification (50, 100 and 500 µg L−1) were used. Results The recovery of all pharmaceuticals, with the exception of tetracycline, from any soil was between 72 and 113%. In the validation procedure, recoveries of fortified samples ranged from 80 to 99%, the relative standard deviations ranged between 1.2 and 11.8%, and the LOQ between 20 and 36.9 μg kg−1. Conclusion The results of the present study confirmed the validity of the modified QuEChERS method for the extraction of pharmaceuticals from soils in the range 50–500 μg kg−1. Graphical Abstract

A method was developed for the determination of 14 anabolic androgenic steroids including trenbolone, boldenone and nandrolone in animal derived foods by liquid chromatography-tandem mass spectrometry. The samples were added to ammonium acetate buffer and enzymatic hydrolyzed by β-glucuronidase and arysulfatase. The hydrolyzates were extracted with 20 mL acetonitrile, and then 10 mL supernatant was degreased by 10 mL acetonitrile saturated hexane, purified with 50 mg C18, 50 mg PSA and 300 mg neutral alumina powder including 300 mg MgSO4. Then the analytes were separated by C18 column with gradient elution using 0.1% formic acid and acetonitrile as the mobile phase, detected in positive multiple reaction monitoring (MRM) and quantified with matrix-matched external standards. The linear regression correlation coefficients for the compounds were all higher than 0.992 in the range from 0.1 to 10 ng/mL. The limits of detection and the limits of quantification were 0.3 and 1.0 μg/kg respectively. The recoveries at the addition levels of 1.0, 2.0 and 10 μg/kg were in the range of 75.7%~104.1%, with relative standard deviations (RSDs) of 3.60%~12.1%. This method had high effectivity, good reproducibility, simple operation and high efficiency, and could be used for the rapid determination needs of common anabolic androgenic steroids in foodborne stimulants in the Winter Olympic Games.

Chlorothalonil is an organochlorine fungicide that blocks the respiratory process of cells and persists in agricultural products because it is used extensively to prevent fungal diseases. An analytical method of chlorothalonil using the modified QuEChERS method and gas chromatography– mass spectrometry (GC-MS/MS) was developed to analyze the residue in agricultural commodities distributed in Republic of Korea. Acetonitrile, including acetic acid and formic acid, was used to compare the extraction efficiency. The extraction and purification processes were established by comparing three versions of the QuEChERS method and various dispersive solid-phase extraction (d-SPE) combinations. Ultimately, 1% formic acid in acetonitrile with QuEChERS original salts and d-SPE (PSA, C18) were selected for the extraction and clean-up procedures for method validation and establishment. Five agricultural commodities, viz., brown rice, mandarin, soybean, pepper, and potato, were examined to validate the established method, which displayed excellent linearity, with a coefficient of determination of R2 = 0.9939–0.997 in the calibration curve range of 0.002–0.1 mg/kg. The limits of detection (LOD) and quantification (LOQ) were calculated to be 0.003 mg/kg and 0.01, respectively, for the method. The LOQ value satisfied the suitable level for the Positive List System (PLS). The mean recovery of chlorothalonil was 79.3–104.1%, and the coefficient of variation was

Graphitized carbon black (GCB) in the traditional QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was used to remove the interfering substance chlorophyll in vegetable and fruit samples for pesticide residues determination. However, it not only adsorbs pigments, but also adsorbs some planar and aromatic pesticides. In order to solve the shortcoming, a core-shell magnetic molecularly imprinted polymer (Fe3O4@MIP) that can specifically recognize and adsorb chlorophyll was synthesized, and an advanced QuEChERS method with the Fe3O4@MIP as a purification material was developed. This advanced method presents detection that is highly sensitive, specific, and reproducible for planar and aromatic pesticides. The limits of detection (LOD) ranged from 0.001–0.002 mg kg−1, and the limit of quantification (LOQ) was 0.005 mg kg−1. The recovery for the planar and aromatic pesticides was within 70–110% with the associated relative standard deviations < 15% in leek samples by the advanced QuEChERS method. However, in the traditional QuEChERS method with GCB, the recovery of most planar and aromatic pesticides was

Linear alkyl benzene sulfonates (LASs) with alkyl chains from C10 to C14 are the most commonly used anionic surfactants in household laundry. However, LAS toxicity toward agricultural soil further could be formed at a risk for fruits and vegetables grown on the land, so that to develop a sensitive and precise analytical technique for determination of trace residual sulfonates in vegetables is very important for health. This study developed a QuEChERS extraction coupled to liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for analyzing LASs in vegetables and fruits. The best results were obtained using acetonitrile as the extraction solvent combined with 25 mg primary secondary amine and 25 mg graphitized carbon black as sorbents. The linearity ranged between 1 and 250 ng/mL as well as limit of quantification (LOQ) was obtained in the range of 0.01–0.23 ng/mL of the proposed analytical method. The proposed method was utilized to detect the real spinach samples and water spinach planted with LASs‐spiked water, and the results showed the trace LASs were detected with concentration between 1.8 and 29.1 ng/g. In this study, a thorough optimization and validation of different amount of sorbent cleanup efficiency approaches was performed for the first time for the analysis of LAS. [ABSTRACT FROM AUTHOR]

Background Antibiotic residues in milk are a well-known hazard in the dairy food chain. Detection methods for these residues, such as nonspecific microbiological inhibitor tests or group-specific receptor tests, are relatively inexpensive, easy to use, and widely applied to ensure food safety. In contrast, specific detection by liquid chromatography–tandem mass spectrometry (LC–MS/MS)—although a critical, complimentary method to confirm the results of nonspecific testing—is relatively costly, time-consuming, and laborious. Furthermore, sample processing before LC–MS/MS analysis requires unique preparation procedures for different groups of antibiotic compounds. Objective To simplify and speed up specific antibiotic residue detection, a low-cost, passive, and single-step method to fractionate analytes in raw milk was developed. Methods Untreated raw milk was fractionated into its water and fat/protein phases using a Fractionation of Milk for Trace Analysis of Contaminants and Residues for Antibiotics (FraMiTrACR® AB) fractionation unit. The water fraction was then analyzed by LC–MS/MS. The analyte fractionation method was evaluated against a Quick Easy Cheap Effective Rugged and Safe (QuEChERS)-based method for sample preparation. Results Our method allows qualitative and quantitative detection of substances from the penicillin, cephalosporin, macrolide, lincosamide, sulfonamide, tetracycline, and fluoroquinolone groups of antibiotics. Detection limits are below the legally prescribed maximum residue levels, allowing reliable, specific, and rapid validation of a positive result in nonspecific microbiological inhibitor tests. Conclusion Analyte fractionation by FraMiTrACR AB is a faster alternative to QuEChERS-based sample preparation for the detection of antibiotic substances in milk. Highlight This method describes a low-cost, environmentally friendly, passive, and single-step milk analyte fractionation. As an alternative to QuEChERS-based preparation, this fractionation method simplifies and speeds up the process for specific antibiotic residue detection. [ABSTRACT FROM AUTHOR]

Objective: A rapid method for determination of bongkrekic acid in Auricularia auricular was developed using QuEChERS in combination with UHPLC-MS/MS. Methods： In this study, Several important experimental parameters, including type of extraction solvent, extraction time, adsorbent type and adsorbent dosage were effectively optimized using spiked samples. The sample were shaken with methanol containing 1% ammonia water, and then carried out by the C18 adsorbent purification. Results： The bongkrekic acid was determined within 4 minutes by negative ion multiple reaction monitoring mode analysis and external standard method. The linear range was 0.05~10.00 ng/mL （r＞0.998 3）. The limit of detection （LOD） was 2 μg/kg, respectively. The average recovery rate at different levels（low, medium and high） the intra-batch （n=6） was 74.4%~91.6%, the inter-batch （n=3） were 74.9%~89.4% with a RSD ranging from 3.3%~9.2%. Conclusion： The developed method shows simple, rapid, excellent recovery and stable repeatability, and the limit of detection lower than the existing detection standards. It is suitable for the effective detection of bongkrekic acid in Auricularia auricular samples.

QuEChERS method was used in pretreatment, and 10 kinds of organophosphorus pesticide residues in mango samples were detected by triple quadrupole GC-MS. The accuracy and feasibility of the method were determined by linear relationship, relative standard deviation and addition recovery rate. The linear correlation coefficient R of 10 organophosphorus pesticides in the range of 0. 01-0. 40 mg / L is greater than 0. 996, and the linear relationship is good. The relative standard deviation of 10 organophosphorus pesticides in 0. 04 mg / L mixed standard solution is 1. 44%-4. 10%, which meets the detection requirements. The average recovery rate of 10 organophosphorus pesticides was 75. 00- 112. 50% when the mixed standard solution with the concentration of 0. 02, 0. 04, 0. 08, 0. 16 and 0. 32 mg / L was added. The results show that the method is accurate in qualitative analysis and simple in operation, and it is suitable for the daily detection of organophosphorus pesticide residues in mango samples. [ABSTRACT FROM AUTHOR]

A modified rapid, simple quick, cheap, effective, robust and safe (QuEChERS) extraction method was developed for the simultaneous extraction and purification of seven antibiotic residues in lettuce, carrot and tomato using liquid chromatography UV detector. The method was validated for linearity, sensitivity, accuracy, repeatability, and reproducibility at six concentration levels for all matrices, according to the guidelines of UNODC. A matrix-matched calibration method was used for the quantitative analysis. Linear range of 0.01–250 μg kg−1 for target compounds with correlation coefficient (R2) 0.9978–0.9995 was obtained. The limits of detections (LODs) and quantifications (LOQs) were 0.02–2.48 μg kg−1 were 0.06–7.52 μg kg−1, respectively. The average recoveries of the seven antibiotics ranged from 74.5 to 105.9%, with relative standard deviation RSD (%)

An effective and sensitive analytical method was developed to quantify the most common pesticide residues (difenoconazole, dimethoate, pymetrozine, and chlorantraniliprole) used for brinjal cultivation in Bangladesh. The quantification of the analytes was done using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted using a modified QuEChERS method and followed by purification with dispersive solid phase extraction (d-SPE) sorbents (PSA, GCB, and C18). Matrix-matched calibration with a regression coefficient R2 ≥ 0.9964 were used to minimize the brinjal matrix effect. The method was validated in quintuple (n = 5) at five different spiked levels (8–400 μg/kg) having recoveries in the range of 70.3–113.2% with relative standard deviations RSDs ≤6.8%, limits of detection (LOD) and limits of quantification (LOQ) was in the range of 0.15–0.66 μg/kg and 0.4–2.0 μg/kg, respectively, for the four analytes. A total 100 samples (50 samples directly from fields of Jessore district, Bangladesh and 50 samples from local market of Dhaka, Bangladesh) were collected to analyse the pesticides residue. The result showed that pesticides residue was found in both the field and market collected samples, 54% and 38%, respectively. The overall mean residue levels of four pesticides in field samples were significantly higher than those of market samples. Moreover, 20% of the field samples and 10% of the market samples had dimethoate residues, which were the most abundant among the four analytes and it ranged from 0.017 to 0.252 mg/kg. In terms of health risk assessments, dimethoate showed the highest estimated daily intake (EDI) and hazard quotient (HQ) values that are 3.02 × 10−5 mg/kg/day and 1.51%, respectively, in field samples. Till now, there have been no regulations or guidelines for the maximum admissible pesticide residue in Bangladesh. Therefore, the above findings will be an initial step for the regulatory authorities of Bangladesh to implement regulations and guidelines for pesticide usage.

A method for the determination of 14 pesticide residues in tea was developed by QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) pretreatment combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The tea samples were extracted with acetonitrile (with 1% acetic acid), purified using QuEChERS purification columns and then analyzed by UPLC-MS/MS. The effects of four purification columns on tea extracts and the recoveries of pesticide residues were compared. The column with better purification effect and recovery was selected to further investigate the matrix effect, linear relationship, and recovery of the method. The results showed that the detection limit of the method was 0.001~2.000 μg/L, and the limit of quantification was 0.003~5.000 μg/L. Reliable linear relationship within the corresponding concentration range were observed for 14 pesticides, with coefficient of determination between 0.9926 and 0.9989. The average recoveries were 71.2%~117.4% at the spiking levels of 100, 500, and 800 μg/kg with RSDs at the range of 1.1%~14.2%. This method showed its advantages of simple and fast operation, sensitivity and recovery rate, meeting the requirements for determination of multi pesticide residues in tea.

A method for the simultaneous determination of 24 sulfonamide antibiotics including sulfamethazine, sulfaguanidine, sulfanilamide and so on in fish products was established by QuEChERS coupled with ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). The optimal experimental conditions were determined by optimizing the chromatographic and mass spectrometric conditions and the QuEChERS pre-treatment technique. The samples were extracted by acetonitrile under ultrasonication, and then purified by C18 and anhydrous MgSO4. The solvent was detected by UPLC-MS/MS after filtering through 0.20 μm microporous membrane. The separation was performed on an Eclipse XDB-C18 column (4.6 mm × 100 mm, 1.8 μm) using acetonitrile −0.1% formic acid aqueous solution as the mobile phase, and determined with positive ion mode of electrospray ionization (ESI) under multiple reaction monitoring (MRM). Then the matrix matching external standard method was used for quantitative analysis. The results indicated that the 24 sulfonamide antibiotics showed good linearity in the respective linear range with the correlation coefficients (r) higher than 0.999. The average recoveries at three spiked levels of 5, 10 and 50 µg/kg ranged from 80.0% to 116.4% with the relative standard deviation (RSD) of 0.8%~9.4% (n=7). Moreover, the limits of detection (LOD) were 0.01~0.48 µg/kg and the limits of quantification (LOQ) were 0.02~1.59 µg/kg. The method was simple, rapid, selective and sensitive for the high-throughput detection of 24 sulfonamide antibiotics in fish products.

Tsampa may contain pesticide residues and mycotoxins, which may pose a risk to human health. Currently, pesticide detection and mycotoxin detection are two independent experiments. To improve the efficiency of the analysis, a method based on QuEChERS combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the simultaneous determination of 78 pesticides and 16 mycotoxins in tsampa was developed. All the target compounds showed good linear correlation with correlation coefficients ( R 2 ) greater than 0.9990. The limits of detection (LODs) and limits of quantification (LOQs) were in the ranges of 0.10-3.00 μg kg -1 and 0.40-10.00 μg kg -1 , respectively. The average recoveries of the pesticides and mycotoxins spiked at the 1, 2, and 10-fold LOQ were in the range of 73.0-115.2%, and the relative standard deviations (RSDs) were lower than 11.7%. This method was applied to 19 batches of real samples in which 32% of samples exceeded the maximum residue limits of the European Union involving aflatoxin G2, ochratoxin A, and hexaconazole. It proved to be excellent, efficient, greatly simplified, and highly applicable, which could reduce the workload and time significantly for the daily monitoring of the pesticides and mycotoxins in tsampa.