Modified Quick, Easy, Cheap, Effective, Rugged, And Safe Method Research Articles

Dissipation and residue analysis of novel nematicide trifluorocide in ginseng and soil using modified QuEChERS method coupled with HPLC-MS/MS

In the present study, an analytical method that combined a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method and high-performance liquid chromatography coupled with tandem mass spectrometry was developed to determine trifluorocide in fresh and dried ginseng roots, plants (stems and leaves), and soil. At three spiked levels (0.01, 0.1, and 1.0 mg kg−1), the mean recoveries (n = 15) of trifluorocide from fresh and dried ginseng roots, plants, and soil were in the range of 95.6 − 109.7%, with relative standard deviations less than 10.0%. The limits of quantitation of different matrices were determined to be 0.01 mg kg−1. Dissipation and residue study of trifluorocide was conducted in ginseng cultivation ecosystems in Northeast China. The t 1/2 (half-life) of trifluorocide in ginseng fresh roots, plants, and soil were 8.3–13.1 days, 7.4–10.9 days, and 8.8–10.6 days, respectively. The terminal residues of trifluorocide in ginseng fresh roots were less than 0.01 mg kg−1 after 35 days of trifluorocide application. This study could be beneficial in residue analysis and assist in the scientific application of trifluorocide during ginseng cultivation.

Optimization and validation of a method for the determination of acidic pesticides in cabbage and spinach by modifying QuEChERS procedure and liquid chromatography–tandem mass spectrometry

A quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed and combined with liquid chromatography–tandem mass spectrometry to analyze 12 acidic pesticides in cabbage and spinach. The extraction solvents, phase partition salts and sorbents effect was studied to optimize the method followed by dilution before sample injection. The extraction involved 5% formic acid in acetonitrile, and the liquid-liquid partition was salt-induced. Carbopack Z, a high surface area graphitized carbon black, was a new sorbent used in the clean-up. The results show that Carbopack Z effectively removes interferences with little loss of acidic pesticides. All tested pesticide recoveries were satisfactory when Carbopack Z was combined with C18 in the clean-up at optimized condition. After clean-up, the extract was subjected to 10-fold dilution to sufficiently reduce the matrix effect (<20%). The limit of quantification (LOQ) was 1–5 ng/g, and the mean recovery was between 95 and 110% with a relative standard deviation <20% (between 2% and 10%) for the spiking of three concentrations: 5, 50, and 500 ng/g. The extract was less pigmented in the modified QuEChERS method than its original version. Thus, the modified method is a useful alternative for investigating the acidic pesticide residues in cabbage and spinach.

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.

Determination of Hexabromocyclododecanes in Fish Using Modified QuEChERS Method with Efficient Extract Clean-Up Prior to Liquid Chromatography–Tandem Mass Spectrometry

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation method coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS) was proposed for the determination of α-, β-, and γ-hexabromocyclododecane (HBCD) diastereomers in whole-fish homogenate samples. The main modification of the QuEChERS method concerned a clean-up step in which the combination of pH-tuned dispersive liquid–liquid microextraction (DLLME) with 18.4 M H2SO4 digestion allowed to successfully eliminate the matrix substances from the final extract. For the target HBCDs, good response linearity was obtained with coefficients of determination (R2) &gt;0.998 for the concentration range corresponding to 0.1–50 ng of analyte per g of sample. Limits of quantifications (LOQs) were 0.15–0.25 ng g−1 ww (wet weight), and the recoveries from samples spiked at levels of 0.5 and 5 ng g−1 ranged from 89% to 102% with relative standard deviations &lt;7.5%. The accuracy of the method was verified by analysis of the NIST standard reference material SRM 1947, and a good agreement (90%) was obtained with the certified value for the α-HBCD present in the sample. Finally, the method was applied to the analysis of 293 fish samples collected in water bodies from all over Slovakia, in which the highest concentrations were determined for α-HBCD with the maximum value of 31 ng g−1 ww.

Screening for twenty-eight target anabolic-androgenic steroids in protein supplements using QuEChERS extraction followed by liquid chromatography-tandem mass spectrometry

ABSTRACT Anabolic-androgenic steroids (AASs) are very potent muscle builders, and professional sportsmen often take protein supplements to improve their performance. Several studies have emphasised that protein supplements may contain undeclared AASs banned by the International Olympic Committee/World Anti-Doping Agency. The widespread occurrence and abuse of contaminated protein supplements is extremely dangerous because of their side effects. To minimise the chances of an unattended positive doping test or to avoid serious health problems, adequate screening methods for the detection of a wide range of steroids is essential. To address this requirement, a rapid and effective modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method was developed and validated to screen and quantify the simultaneous analysis of twenty-eight AASs in protein supplements using LC-MS/MS. The validated method was applied to 198 protein supplements collected from on-line and, off-line markets, and direct purchase from overseas between 2019 and 2020. Of the 198 samples, two samples contained testosterone and stanozolol at concentrations of 0.27 μg/g and 0.023 μg/g, respectively. In addition, 5α-hydroxylaxogenin was detected for the first time in three products purchased in Korea from overseas. The modified QuEChERS method was established and successfully applied to screen and determine AASs as a measure of continuous control and supervision in protein supplements.

Determination of 5-Hydroxymethyl-2-Furaldehyde in Cooked Japonica Rice Using a Modified QuEChERS Method Combined with Dispersive Liquid-Liquid Microextraction Followed by UPLC-ESI-MS/MS

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method combined with dispersive liquid-liquid microextraction (DLLME) pretreatment was developed for the determination of 5-hydroxymethyl-2-furaldehyde (HMF) in cooked japonica rice. Optimum conditions of the proposed method include MgSO4 (1 g), NaCl (0.5 g), C18 (60 mg), PSA (50 mg), the extraction solvent (CHCl3), dispersing solvent volume/extraction solvent volume (4:1), ultrapure water volume/the total volume of dispersing solvent volume and extraction solvent volume (1:1), and pH (7). HMF was concentrated by the clean-up method with the enrichment factor of 1.98. The separation of HMF was performed on an ACQUITY UPLC BEH-RP C18 column (2.1 mm × 100 mm, 1.7 μm) by the UPLC-ESI-MS/MS (ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry). Acceptable values of HMF were achieved for the following parameters: recoveries between 82.87 and 110.48% with the relative standard deviation lower than 8.68%, accuracy in the range of 93.95–114.22%, precision (< 8.76%), limit of detection (LOD) (0.1 μg/L), and limit of quantification (LOQ) (0.3 μg/L). The concentrations of HMF were less than 1.13 μg/kg in rice samples, conspicuously increased with warming time. The color of rice samples, especially the b* value (in the range of 6.02–11.43), was well correlated with the content of HMF and the warming time.

Development and Application of the Dispersive Solid-Phase Extraction Method Based on Molecular Imprinted Polymers for Removal of Matrix Components of Bivalve Shellfish Extracts in the GC–MS/MS Analysis of Amide/Dinitroaniline/Substituted Urea Herbicides

A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation method coupled with gas chromatography–tandem mass spectrometry has been developed for the simultaneous analysis of amide/dinitroaniline/substituted urea herbicides in bivalve shellfish samples. A molecularly imprinted polymer (MIP) synthesized through bulk polymerization exhibited strong group–selective interactions with pigments, including β-carotene, chlorophyll A, and fucoxanthin, in bivalve shellfish extracts. Afterward, a modified QuEChERS method based on MIPs and primary and secondary amines was established to effectively remove matrix components in bivalve shellfish samples. Under the optimal conditions, good linearities were obtained in all of the analytes with R2 larger than 0.9995. Limits of quantification were in the range of 0.03–8.88 μg kg−1, respectively. The recoveries of all of the herbicides spiked at three concentrations of 10, 25, and 50 μg kg−1 in blank bivalve shellfish samples ranged from 81 to 109% with intra-day and inter-day relative standard deviations less than 8%, respectively. Results demonstrated that the proposed QuEChERS method coupled with GC–MS/MS was applied successfully to simultaneously determine 26 amide/dinitroaniline/substituted urea herbicides in bivalve shellfish.

Determination of 10 pesticides, newly registered in Egypt, using modified QuEChERS method in combination with gas and liquid chromatography coupled with tandem mass spectrometric detection

ABSTRACTThe analysis of pesticide residues in food is currently an increasingly important task. In this work, a rapid and sensitive protocol has been developed for the determination of ametoctradin, amisulbrom, bromoxynil-octanoate, chlorantraniliprole, cyhalofop-butyl, hymexazol, metaldehyde, prodiamine (dithiopyr), sulcotrione and tolfenpyrad. The extraction was done using the citrate buffer acetonitrile-based QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation technique. Acetonitrile extracts were directly injected into the liquid chromatography-tandem mass spectrometry system, and solvent exchange was used prior to the injection in the gas chromatography system. Different exchange solvents were evaluated and a mixture of n-hexane:acetone (9:1) was chosen. Matrix effects were evaluated and a relation between the signal suppression/enhancement and the co-extracted matrix was established. The validation study was carried out on cucumber, banana and lemon matrices following SANTE/11813/2017 of the European quality control guidelines. The precision and trueness of the method were determined from recovery experiments on six replicates of spiked blank samples at 0.01, 0.05, and 0.1 mg/kg for each commodity. The range of the obtained recoveries was 70–111%, with RSD values of <18% for all the tested concentrations. The only exception was hymexazol at 0.01 mg/kg in banana and cucumber.

Determination of Phenolic Compounds in Red Sweet Pepper (Capsicum annuum L.) using a Modified QuEChERS Method and UHPLC-MS/MS Analysis and Its Relation to Antioxidant Activity

In the present work, a fast, easy and efficient analytical method was developed and validated for the determination of phenolic compounds (4-hydroxybenzoic, vanillic, caffeic, p-coumaric, sinapic, ferulic and ellagic acids, and naringenin) in red sweet pepper. Extraction of phenolic compounds was carried out using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method, followed by separation and detection using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). When the acetate version of the QuEChERS method was used, higher amounts of the phenolic compounds were extracted. In the dispersive solid phase extraction (d-SPE) clean-up step, combination of 50 mg of octadecylsilane (C18) and 7.5 mg of graphitized carbon black (GCB), resulted in the greatest removal of interferents, especially carotenoids, without significant retention of phenolic compounds. The recoveries for the proposed method were 82-103%, the limits of quantification were 2-150 µg kg-1, and the precision values expressed in terms of relative standard deviation (RSD) were ≤ 15%. The method developed was successfully applied to the analysis of different red sweet pepper cultivars.

Development of a modified QuEChERS method based on magnetic multiwalled carbon nanotubes for the simultaneous determination of veterinary drugs, pesticides and mycotoxins in eggs by UPLC-MS/MS.

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was developed for the simultaneous determination of veterinary drugs, pesticides and mycotoxins in eggs by ultrahigh-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Several extraction conditions were tested and optimized, and the obtained extraction efficiency of all the targeted compounds (particularly macrolides) could fulfill the requirements. In the purification procedure, magnetic multiwalled carbon nanotubes (Fe3O4-MWCNTs) were used as adsorbents, and an external magnet was utilized to achieve a faster adsorbent separation, compared to the traditional centrifugation process. The recoveries of all analytes were in the range of 60.5%-114.6% at three fortified levels with relative standard deviations (RSDs) of less than 20%, and the LOQs ranged from 0.1 μg·kg-1 to 17.3 μg·kg-1. This method was successfully applied to the analysis of egg samples, demonstrating its applicability and suitability for the routine analysis of multiclass residues in egg samples.

Quantification of five neonicotinoids in human urine by modified QuEChERS with isotope dilution mass spectrometry: a preliminary study for the development of certified reference material

ABSTRACTA study for the quantification method of neonicotinoid pesticides (Neos) in human urine that aims to develop the certified reference material (CRM) in the future was carried out. A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method based on dispersive solid phase extraction (d-SPE) with isotope dilution mass spectrometry (IDMS) was evaluated for the quantification of five Neos (acetamiprid, dinotefuran, imidacloprid, thiacloprid and thiamethoxam) in human urine control by optimisation of the extraction solvent, and the type and amount of d-SPE material. Two types of human urine controls (sample A and B) containing 5 μg/kg and/or 25 μg/kg of Neos were prepared and employed for this study. The results of spike test using sample A (2 mL) obtained by modified QuEChERS method with acetone extraction (10 mL) and d-SPE using a strong cation exchanger (silica gel modified with benzenesulphonic acid phase, SCX) 500 mg were as follows: 97.8%–103.1% for 5 μg/kg and 97.2%–102.7% for 25 μg/kg (described as percentage by the quantification results of IDMS relative to the spiked amount of pesticides). These results were comparable to those by SPE cartridge method using SCX functionalised hydrophilic styrene divinylbenzene (PCX). The repeatabilities of the analyses, represented as relative standard deviations, were also comparable for spike level 5 μg/kg and 25 μg/kg of Neos: 0.1%–7.2% for modified QuEChERS with IDMS and 0.2%–5.6% for PCX cartridge method. The results of spike test using sample B for a spike level 5 μg/kg were 96.0%–100.6%. These results indicate that modified QuEChERS method with IDMS can be used for the development of certified reference material and has the potential to use for the quantification of Neos in real human urine.

Determination of organochlorine pesticides (OCPs) in breast milk from Rio Grande do Sul, Brazil, using a modified QuEChERS method and gas chromatography-negative chemical ionisation-mass spectrometry

ABSTRACTThe food chain is the main source of exposure to humans by organochlorine pesticides (OCPs) due to the bioaccumulation. Breast milk can accumulate OCPs, so this matrix is often used as an environmental bioindicator. The currently available methods for the determination of several OCPs and metabolites in breast milk involve, in general, multi-step sample preparation and quantification techniques with low selectivity, high cost and much time and labour. Thus, a fast and efficient method based on sample preparation using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with gas chromatography coupled to mass spectrometry with negative chemical ionisation (GC-NCI-MS) was developed, validated and applied for determination of 16 OCPs and metabolites in breast milk samples. The extract was cleaned by dispersive solid-phase extraction (d-SPE) using MgSO4 and C18, evaporated in a Turbovap® system, redissolved and analysed by GC-NCI-MS. The method was validated showing acceptable recoveries (72–118%) and precision (RSD <19%). Method limits of detection (LODs) and quantification (LOQs) ranged from 0.75 to 7.5 ng g−1 and from 2.5 to 25 ng g−1 lipid, respectively. The method was successfully applied to 20 samples of breast milk from different regions of the Rio Grande do Sul state, Brazil, of which 75% contained residues below the LOQs.

Dissipation Dynamic and Final Residues of Oxadiargyl in Paddy Fields Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry Coupled with Modified QuEChERS Method.

Oxadiargyl, which binds to the protoporphyrinogen oxidase IX to exhibit herbicide activity, is mainly used in the prevention of certain perennial broadleaved and grass weeds during the preemergence of rice in paddy fields. However, oxadiargyl affects the germination and seedling growth of rice, causing damage to the plant and reducing rice yield. Hence, monitoring fate and behaviour of oxadiargyl in rice paddy fields is of great significance. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation method coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established in paddy water, paddy soil, rice straw, paddy hull, and brown rice. We validated this method for the first time in the analysis of the dissipation dynamic and residues of oxadiargyl over two years (2015–2016) at three sites in China. The average recoveries of oxadiargyl ranged from 76.0 to 98.8%, with relative standard deviations of 3.5–14.0%. The dissipation curves for paddy soil fit to a first-order kinetic equation, revealing that oxadiargyl degraded rapidly in paddy soil with half-lives (t1/2) of 4.5–7.6 days. The final oxadiargyl residues in all samples remained below the detection limit and the maximum residue limit in China (0.02 mg kg−1) and Japan (0.05 mg kg−1) during the harvesting dates and were not detected in rice straw.

Determination of fipronil and its metabolites in chicken egg, muscle and cake by a modified QuEChERS method coupled with LC-MS/MS

ABSTRACTAn easy-to-use method for determining the levels of fipronil and its metabolites (fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide) in chicken egg, muscle and cake was developed and validated using a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) approach coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The samples were extracted using acetonitrile, salted out with sodium chloride at −20°C, and then purified by combined PSA and C18 phases and anhydrous magnesium sulphate. The recoveries were 80.4–119% with relative standard deviations (RSDs) < 10% for the different matrixes. The validated method was used to analyse the target compounds in 214 real samples collected in Beijing. The metabolite fipronil-sulfone was detected in most of the samples and was identified as the main residue in the egg and cake. The method was validated using a proficiency test for fipronil in products of animal origin published by Wageningen University & Research in 2017.

Inexpensive, effective novel activated carbon fibers for sample cleanup: application to multipesticide residue analysis in food commodities using a QuEChERS method.

Phenolic resin based activated carbon fibers (ACFs) were applied for the first time as a reversed-dispersive solid-phase extraction (r-DSPE) sorbent. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied to determine 26 pesticides (organophosphates, organochlorines, synthetic pyrethroids, and herbicides) in different complex matrices, including cauliflower, cucumber, banana, apple, wheat, and black gram. Different physicochemical characterization techniques were used to investigate the engineering and structural properties of the r-DSPE sorbent. All the chromatographic analyses were performed with a gas chromatograph equipped with an electron capture detector. The recoveries of all 26 pesticides were acceptable (70-120%), with relative standard deviations of less than 15%. The limit of detection and the limit of quantification were 1.13-5.48 ng/g and 3.42-16.60 ng/g, respectively. In the original QuEChERS method, primary secondary amine is extensively used as the r-DSPE sorbent in the cleanup process, but it is eightfold more expensive than the ACFs used in this study. Therefore, the modified QuEChERS method using ACFs during the cleanup process is more efficient, cheaper, and more robust to determine pesticides from different types of matrices, including vegetables, grains, and fruits, and ACFs could be used as a cost-effective alternative to primary secondary amine. Graphical Abstract Sample clean-up using PSA and ACF as r-DSPE sorbent in QuEChERS method.

Validation of a Modified QuEChERS Method for the Determination of 167 Pesticides in Milk and Milk Products by LC-MS/MS

A liquid chromatography tandem mass spectrometry (LC-MS/MS) method with modified QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction cleaning process was comprehensively validated for determination of 167 pesticide residues in three matrices: milk, cheese and cream. Optimisation of the mass spectrometry parameters was performed by injecting pesticide standard solutions into the electrospray ion (ESI) source. The mass spectrometer was operated in the positive ESI mode. The validation data fulfilled the requirements of the European SANTE/11945/2015 Guideline. The specificity of the developed method is considered satisfactory. Good linearity (R 2 > 0.99) was obtained for all pesticide matrix calibration curves within the range of 0.1–100 μg kg−1. Mean recoveries of all target analytes ranged from 80.4 to 117.3%, and limits of quantification (LOQ) ranged from 1.1 to 13.1 μg kg−1, depending on pesticide residues. The repeatability and within-laboratory reproducibility ranged from 0.2 to 15.1% and from 1.3 to 19.4%, respectively. The uncertainty was not higher than 48% for target analytes in the three matrices. The validated method was successfully applied to screening of milk and milk products, and none of the 167 pesticides investigated was detected in 92 real samples.

Development and validation of modified QuEChERS method coupled with LC-MS/MS for simultaneous determination of cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite in various types of honey and royal jelly.

Over the past few decades, honey products have been polluted by different contaminants, such as pesticides, which are widely applied in agriculture. In this work, a modified EN - quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method was developed for the simultaneous quantification of pesticide residues, including cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite 2,4-dimethylaniline (2,4-DMA), in four types of honey (acacia, wild, chestnut, and manuka) and royal jelly. Samples were buffered with 0.2M dibasic sodium phosphate (pH 9), and subsequently, acetonitrile was employed as the extraction solvent. A combination of primary secondary amine (PSA) and C18 sorbents was used for purification prior to liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI+/MS-MS) analysis. The estimated linearity measured at six concentration levels presented good correlation coefficients (R2)≥0.99. The recovery, calculated from three different spiking levels, was 62.06-108.79% in honey and 67.58-106.34% in royal jelly, with an RSD<12% for all the tested compounds. The matrix effect was also evaluated, and most of the analytes presented signal enhancement. The limits of quantification (LOQ) ranged between 0.001 and 0.005mg/kg in various samples. These are considerably lower than the maximum residue limits (MRL) set by various regulatory authorities. A total of 43 market (domestic and imported) samples were assayed for method application. Among the tested samples, three samples were tested positive (i.e. detected and quantified) only for cymiazole residues. The residues in the rest of the samples were detected but not quantified. We concluded that the protocol developed in this work is simple and versatile for the routine quantification of cymiazole, 2,4-DMA, fipronil, coumaphos, amitraz, and fluvalinate in various types of honey and royal jelly.

Modified QuEChERS method for 24 plant growth regulators in grapes using LC-MS/MS

A multiresidue analytical method was developed for grapes for the following 24 plant growth regulators: 1-naphthylacetamide, 2,3,5-triiodobenzoic acid, 2,4,5-T, 2-naphthoxyacetic acid, 3-indolylacetic acid, 4-(3-indolyl)-butyric acid, 4-chlorophenoxyacetic acid, 4-nitrophenol, 6-benzylaminopurine, N6-isopentenyladenine, butralin, chlormequat chloride, chlorphonim-Cl, cloprop, forchlorfenuron, gibberellic acid 3, gibberellic acid 4, gibberellic acid 7, inabenfide, mepiquat chloride, paclobutrazol, prohydrojasmon, thidiazuron and uniconizole-P. The compounds were extracted from grape samples using an extraction method modified from the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method. Liquid chromatography – tandem mass spectrometry was used for the detection and quantification of the compounds. Validation of the method was performed by using recovery studies at both intra-day and inter-day intervals, as well as by evaluation of the matrix effect, limit of quantification, trueness and precision. We used matrix-matched calibrations for the quantification of the compounds, which all resulted in determination coefficients (r2) higher than 0.995. The limit of quantification ranged from 0.1 to 5 ng/mL. Recovery studies using three spiking concentrations at varying levels showed recoveries of 70.2–112.6% and 67.5–101.8% at intra-day and inter-day intervals, respectively. Relative standard deviations were below 20% for the recovery studies. The extraction method were further validated by performing recovery study and matrix effect test in six different grape varieties from Taiwan and the United States and all resulted in comparable results. Application of the established method to 50 grape samples, resulted in the detection of chlormequat chloride and forchlorfenuron residues in the tested grapes. The results of the method validation and real sample analysis shows the extraction method is therefore suitable for routine monitoring of residue in grapes.

Determination of Polychlorinated Biphenyls in Fish Tissues from Shanghai Seafood Markets Using a Modified QuEChERS Method.

Optimized Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) pretreatment methods for determination of six polychlorinated biphenyls (PCBs) residues in fish and aquatic invertebrates samples were investigated. Large volume injection (LVI) coupled gas chromatography tandem mass spectrometry (GC-MS/MS) with selected reaction monitoring (SRM) was used to provide a very sensitive and selective means of analyzing PCBs via internal calibration. Three analytical processes were validated and compared, and the florisil Celite®545 pretreatment method was selected. Performance characteristics, such as linearity, limit of detection (LOD), limit of quantization (LOQ), recovery and precision (relative standard deviation, RSD) were studied. The method was applied to 233 samples obtained from local markets, which was useful and thus suggested that the method could serve as a screening model for PCB residues analysis.

Determination of mancozeb residue in fruit by derivatization and a modified QuEChERS method using ultraperformance liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry method with derivatization and a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation was developed for the determination of mancozeb in fruits. The target compound was determined in less than 4.0min with use of an electrospray ionization source in positive mode. The limits of detection and the limits of quantification ranged from 1.0 to 3.2μgkg-1 and from 10 to 15μgkg-1 in fruit respectively. The linearity was excellent for mancozeb (R 2 ≥ 0.9920). Recoveries in five matrices were obtained at three spiking levels (0.02, 0.1, and 1mgkg-1). For all concentrations, the mean recoveries ranged from 84.0% to 95.9%, with repeatability relative standard deviation (n = 5) of 0.6 - 7.0%. The interday reproducibility relative standard deviation (n = 3) ranged from 1.4% to 5.5%. This method could be used for the routine detection of mancozeb residues in fruit. Graphical abstract The derivation of mancozeb and the detection process of derivative product by UPLC-MS/MS.