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Rates of degradation of λ-cyhalothrin and methomyl residues in grape are reported. The dissipation behavior of both insecticides followed first-order rate kinetics with similar patterns at standard and double-dose applications. Residues of λ-cyhalothrin were lost with pre-harvest intervals (PHI) of 12.0–12.5 and 15.0–15.5 days, corresponding to the applications at 25 and 50  g a.i. ha -1 , respectively. In the case of methomyl, residues were lost with PHI of 55.0 and 61.0 days, following applications at 1 and 2  kg a.i. ha -1 , respectively. The PHI, recommended on the basis of the experimental results, was shown to be effective in minimizing residue load of these insecticides below their maximum residue limits (MRLs) in vineyard samples. [ABSTRACT FROM AUTHOR]

The rate of degradation of kresoxim methyl and its effect on soil extra-cellular (acid phosphatase, alkaline phosphatase and β-glucosidase) and intra-cellular (dehydrogenase) enzymes were explored in four different soils of India. In all the tested soils, the degradation rate was faster at the beginning, which slowed down with time indicating a non-linear pattern of degradation. Rate of degradation in black soil was fastest followed by saline, brown and red soils, respectively and followed 1st or 1st + 1st order kinetics with half-life ranging between 1–6 days for natural soil and 1–19 days for sterile soils. The rate of degradation in natural against sterilized soils suggests that microbial degradation might be the major pathway of residue dissipation. Although small changes in enzyme activities were observed, kresoxim methyl did not have any significant deleterious effect on the enzymatic activity of the various test soils in long run. Simple correlation studies between degradation percentage and individual enzyme activities did not establish any significant relationships. The pattern and change of enzyme activity was primarily due to the effect of the incubation period rather than the effect of kresoxim methyl itself. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dissipation kinetics of the residues of CPPU, 6-BA, GA3 and Ethephon in grape are reported. [•] Dissipation of residues followed 1st +1st order kinetics. [•] Initial residue of GA3 was below MRL and hence no pre-harvest interval (PHI) is applicable. [•] CPPU, 6-BA and Ethephon residues dissipated with PHIs of 33.5, 12 and 32days, respectively. [Copyright &y& Elsevier]

Abstract: A single quadrupole GC–MS method was optimized for multiresidue determination of 47 pesticides in grapes with limit of quantifications of each compound in compliance with the EU-MRL requirements. Sample preparation involved extraction of 10g sample with 10ml ethyl acetate (+10g sodium sulphate) by homogenization at 15,000rpm followed by centrifugation at 3000rpm. The supernatant was cleaned by dispersive solid phase extraction with primary secondary amine and acidified with 0.1% formic acid. Residues were estimated in selected ion monitoring mode with programmable temperature vaporizer-large volume injection (8μl). All the GC and MS parameters were thoroughly optimized to achieve satisfactory linearity (R 2 >0.99) within 0.01–0.25mgkg−1 with minimum matrix interferences. Recoveries at 0.01 and 0.02mgkg−1 were within 67–120% with associated precision RSD below 19%. The method was successfully applied for analysis of the real world samples for incurred residues. [Copyright &y& Elsevier]

Abstract: Food safety aspects of buprofezin, dimethoate and imidacloprid residues in pomegranate are reported. The residue analysis involved extraction of samples (15g) with 10ml ethyl acetate, cleanup by dispersive solid phase extraction with 25mg primary secondary amine and 25mg C18 sorbents and estimation by LC–MS/MS. The limit of quantification of each analyte was 0.001mgkg−1 with recoveries within 76–109%. The residues of buprofezin and dimethoate were confined to outer rind, which degraded to below the maximum residue limit for the European Union (EU-MRL) after 10.5 and 31.5days at standard dose and 32.0 and 44.0days at double dose. Residues of imidacloprid penetrated into the albedo and membrane, although at less than the MRL in all samples even at double dose. The dietary exposure of buprofezin and imidacloprid was safe on all sampling days; whereas samples with dimethoate appeared safe after 15 and 30days of field applications at standard and double doses, respectively. [Copyright &y& Elsevier]

Abstract: Water based samples such as flavored drinks, juices and drinking water may contain contaminants at ultra trace level belonging to different chemical classes. A novel, simple, low-cost and fast method was developed and validated for trace residue extraction of pesticides, dioxin-like PCBs and PAHs from water and water based samples followed by analysis through gas chromatography (GC) coupled with time-of-flight mass spectrometry (ToFMS). The extraction solvent type, volume; sample volume and other extraction conditions were optimized. This was achieved by extracting 10mL sample with 250μL chloroform by vortexing (1min, standing time of 2min) followed by centrifugation (6000rpm, 5min). The bottom organic layer (200μL) was pipetted out, evaporated to near dryness and reconstituted in 20μL of ethyl acetate+cyclohexane (1:9) mixture resulting in an enrichment factor of 400. The recoveries of all compounds were within 76–120% (±10%) with the method detection limit (MDL) ranging from 1 to 250ng/L depending on the analyte response. The MDLs were 400 times lower than the instrument quantification limits that ranged from 0.4 to 100ng/mL. The method was further validated in water based drinks (e.g. apple, lemon, pineapple, orange, grape and pomegranate juice). For the juices with suspended pulp, the extraction was carried out with 400μL chloroform. The extract was analyzed by GC-ToFMS at both 1D and GC×GC modes to chromatographically separate closely eluting interfering compounds the effect of which could not be minimized otherwise. The resulting peak table was filtered to identify a range of compounds belonging to specific classes viz. polycyclic aromatic hydrocarbons, chlorinated, brominated, and nitro compounds. User developed scripts were employed on the basis of identification of the molecular ion and isotope clusters or other spectral characteristics. The method performed satisfactorily in analyzing both incurred as well as market samples. [Copyright &y& Elsevier]

Abstract: A novel method for the residue analysis of wine spoilage compound 2,4,6-trichloroanisole is reported. Wine (60ml) was extracted with 2ml toluene in presence of 24g MgSO4 and 6g NaCl. Cleanup of the toluene phase by dispersive solid phase extraction with mixture of 100mg CaCl2, 25mg primary secondary amine and 50mg MgSO4 was effective in minimising co-extractives and matrix effects. Time-of-flight and tandem mass spectrometric parameters were optimised to achieve linearity over 0.25–500ngml−1 and method detection limit 0.0083ngml−1 which is well below the odour threshold of 0.04ngml−1. Recoveries at 0.04, 0.2 and 0.8ngml−1 were within 80–110% (±8%). The method was reproducible when tested for Argentinean wines with intra-laboratory Horwitz ratios being <0.20 in white and red wines at both the laboratories of India and Argentina. The method could be successfully applied for incurred wine samples. [ABSTRACT FROM AUTHOR]

Abstract: Two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometric (TOFMS) method was optimized for simultaneous analysis of 160 pesticides, 12 dioxin-like polychlorinated biphenyls (PCBs), 12 polyaromatic hydrocarbons (PAHs) and bisphenol A in grape and wine. GC×GC–TOFMS could separate all the 185 analytes within 38min with >85% NIST library-based mass spectral confirmations. The matrix effect quantified as the ratio of the slope of matrix-matched to solvent calibrations was within 0.5–1.5 for most analytes. LOQ of most of the analytes was ≤10μg/L with nine exceptions having LOQs of 12.5–25μg/L. Recoveries ranged between 70 and 120% with <20% expanded uncertainties for 151 and 148 compounds in grape and wine, respectively, with intra-laboratory Horwitz ratio <0.2 for all analytes. The method was evaluated in the incurred grape samples where residues of cypermethrin, permethrin, chlorpyriphos, metalaxyl and etophenprox were detected at below MRL. [Copyright &y& Elsevier]

Abstract: A multiresidue method is described for simultaneous estimation of 83 pesticides and 12 dioxin-like polychlorinated biphenyls (PCBs) in red and white wines. The samples (20mL wine, acidified with 20mL 1% HCl) were extracted with 10mL ethyl acetate (+20g sodium sulphate) and cleaned by dispersive solid-phase extraction (DSPE) with anhydrous calcium chloride and Florisil successively. The final extract (5mL) was solvent exchanged to 1mL of cyclohexane:ethyl acetate (9:1), further cleaned by DSPE with 25mg primary secondary amine sorbent and analyzed by gas chromatography–time-of-flight mass spectrometry (GC–TOF-MS) within 31min run time. The limits of quantification of most analytes were ≤10–20μg/L. Acidification of wine prior to extraction prevented hydrolysis of organophosphorous pesticides as well as dicofol, whereas treatment with CaCl2 minimized the fatty acid co-extractives significantly. Solvent exchange to cyclohexane:ethyl acetate (9:1) further minimized the co-extractives. Recoveries at 5, 10 and 20ng/mL were >80% for most analytes except cyprodinil, buprofezin and iprodione. The expanded uncertainties at 10ng/mL were <20% for most analytes. Intra-laboratory precision in terms of Horwitz ratio of all the analytes was below 0.5, suggesting ruggedness of the method. Effectively, the method detection limit for most analytes was as low as up to 1ng/mL in both red and white wine, except for cyfluthrin and cypermethrin. [Copyright &y& Elsevier]

Abstract: A comprehensive GC×GC–TOFMS method was optimized for multiresidue analysis of pesticides using a combination of a non-polar (RTX-5MS, 10m×0.18mm×0.2μm) and a polar capillary column (TR-50MS, 1m×0.1mm×0.1μm), connected in series through a dual stage thermal modulator. The method resolved the co-elution problems as observed in full scan one-dimensional GC–MS analysis and allowed chromatographic separation of 51 pesticides within 24min run time with library-searchable mass spectrometric confirmation. Four pesticides, viz. chlorpyrifos-methyl, vinclozoline, parathion-methyl and heptachlor could be baseline separated on GC×GC, which were otherwise closely eluting and interfering each other''s detection in 1D GC–MS run. Similarly, it could be possible to separate myclobutanil, buprofezin, flusilazole and oxyfluorfen on GC×GC. Although in 1D GC–MS, these closely eluting compounds could be identified through deconvolution algorithm and ‘peak-find’ option of the Chromatof® software but the spectral purity significantly improved on GC×GC analysis. Thorough optimization was accomplished for the oven temperature programming, ion source temperature and GC×GC parameters like modulation period, duration of hot pulses, modulation-offset temperature, acquisition rate, etc. to achieve best possible separation of the test compounds. The limit of detection significantly improved by 2–12 times on GC×GC–TOFMS against GC–TOFMS because of sharper and narrower peak shapes. The method was tested for grape matrix after preparing the samples using previously described method and recoveries of the entire test pesticides were within 70–110% at 10ng/g level of fortification. GC×GC–TOFMS was found to be an excellent technique for library-based screening of pesticides with high accuracy and sensitivity. [Copyright &y& Elsevier]

Abstract: A method was validated for the multi-residue analysis of 82 pesticides in grapes at ≤25ng/g level. Berry samples (10g) mixed with sodium sulphate (10g) were extracted with ethyl acetate (10mL); cleaned by dispersive solid phase extraction and the results were obtained by liquid chromatography–tandem mass spectrometry. Reduction in sample size and proportion of ethyl acetate for extraction did not affect accuracy or precision of analysis when compared to the reported methods and was also statistically similar to the QuEChERS technique. The method was rugged (HorRat<0.5) with <20% measurement uncertainties. Limit of quantification was <10ng/g with recoveries 70–120% for most pesticides. The method offers cheaper and safer alternative to typical multi-residue analysis methods for grape. [Copyright &y& Elsevier]