Dissipation and distribution behavior of azoxystrobin, carbendazim, and difenoconazole in pomegranate fruits.

The dissipation behavior and degradation kinetics of azoxystrobin, carbendazim, and difenoconazole in pomegranate are reported. Twenty fruits/hectare (5 kg) were collected at random, ensuring sample-to-sample relative standard deviation (RSD) within 20-25%. Each fruit was cut into eight equal portions, and two diagonal pieces per fruit were drawn and combined to constitute the laboratory sample, resulting in RSDs <6% (n = 6).

Multiresidue analysis of synthetic pyrethroid pesticides in grapes by gas chromatography with programmed temperature vaporizing-large volume injection coupled with ion trap mass spectrometry.

A multiresidue analysis method was optimized and validated for simultaneous estimation of 21 synthetic pyrethroid pesticides and their isomers in grape matrix at 10 ng/g and higher levels. The method involves extraction of a 10 g sample with 10 mL ethyl acetate, cleanup by dispersive SPE with primary-secondary amine (25 mg) sorbent, and estimation by GC/MS/MS large volume injection (LVI) through a programmed temperature vaporizer (PTV) injector. The PTV-LVI parameters of the gas chromatograph and the multiple reaction monitoring (MRM) parameters of the ion trap mass spectrometer were optimized for each compound to achieve the highest SIN.

Optimization of two-dimensional gas chromatography time-of-flight mass spectrometry for separation and estimation of the residues of 160 pesticides and 25 persistent organic pollutants in grape and wine.

Two-dimensional gas chromatography (GCxGC) 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. GCxGC-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.

Ultrasound-assisted emulsification microextraction for determination of 2,4,6-trichloroanisole in wine samples by gas chromatography tandem mass spectrometry.

A fast and effective microextraction technique is proposed for preconcentration of 2,4,6-trichloroanisole (2,4,6-TCA) from wine samples prior gas chromatography tandem mass spectrometric (GC-MS/MS) analysis. The proposed technique is based on ultrasonication (US) for favoring the emulsification phenomenon during the extraction stage. Several variables influencing the relative response of the target analyte were studied and optimized.

Multiresidue analysis of 50 pesticides in grape, pomegranate, and mango by gas chromatography-ion trap mass spectrometry.

A selective and sensitive multiresidue analysis method is reported for simultaneous determination of 50 pesticides of different chemical classes in three commercially important fruits of different nature viz. grape, pomegranate, and mango. The sample preparation method involves extraction of a 10 g sample with 10 mL of ethyl acetate; cleanup by dispersive solid phase extraction with primary secondary amine (PSA, 25 mg) for grape and PSA + graphitized carbon black (25 + 5 mg) for pomegranate and mango; and determination by gas chromatography-ion trap mass spectrometry through multiple reaction monitoring (MRM).

Multiresidue determination and uncertainty analysis of 87 pesticides in mango by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method was optimized and validated for the multiresidue analysis of 87 pesticides in mango at the ≤ 10 ng g(-1) level. The method involves extraction of 10 g of homogenized mango samples (+10 mL of water + 1 g of sodium acetate + 10 g of sodium sulfate) with 10 mL of ethyl acetate; cleanup by dispersive solid-phase extraction with a combination of primary secondary amine (PSA, 50 mg), graphitized carbon black (GCB, 25 mg), and anhydrous sodium sulfate (150 mg); and final estimation by LC-MS/MS with multiple reaction monitoring. Direct analysis (no clean up) resulted in significant suppression in ionization of the majority of the test compounds over the electrospray ionization probe.

Multiresidue analysis of 83 pesticides and 12 dioxin-like polychlorinated biphenyls in wine by gas chromatography-time-of-flight mass spectrometry.

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 20 mL 1% HCl) were extracted with 10 mL ethyl acetate (+20 g sodium sulphate) and cleaned by dispersive solid-phase extraction (DSPE) with anhydrous calcium chloride and Florisil successively. The final extract (5 mL) 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 31 min run time.

Single-laboratory validation and uncertainty analysis of 82 pesticides determined in pomegranate, apple, and orange by ethyl acetate extraction and liquid chromatography/tandem mass spectrometry.

Single-laboratory validation results are reported for the multiresidue determination of 82 pesticides at < or = 10 ng/g levels in pomegranate, apple, and orange. Samples were extracted with ethyl acetate, and the extracts were cleaned up by dispersive solid-phase extraction with primary secondary amine sorbent. The concentrations of the pesticides were estimated within 18 min of chromatographic run time by liquid chromatography/mass spectrometry with multiple-reaction monitoring.

Degradation kinetics and safety evaluation of buprofezin residues in grape (Vitis vinifera L.) and three different soils of India.

Background: This work was undertaken to determine the preharvest interval (PHI) of buprofezin to minimize its residues in grapes and thereby ensure consumer safety and avoid possible non-compliance in terms of residue violations in export markets. Furthermore, the residue dynamics in three grapevine soils of India was explored to assess its environmental safety.

Results: Residues dissipated following non-linear two-compartment first + first-order kinetics.

Degradation kinetics of forchlorfenuron in typical grapevine soils of India and its influence on specific soil enzyme activities.

The rate of degradation of forchlorfenuron, a cytokinin-based plant growth regulator (PGR) was explored in typical grapevine soils of India with simultaneous evaluation of its effect on biochemical attributes of the test soils in terms of the activities of specific soil microbial enzymes. In all the test soils, namely clay, sandy-loam and silty-clay, the dissipation rate was faster at the beginning, which slowed down with time, indicating a non-linear pattern of degradation. Degradation in soils could best be explained by two-compartment 1st+1st order kinetics with half-life ranging between 4-10 days.

Optimization of separation and detection conditions for the multiresidue analysis of pesticides in grapes by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

A comprehensive GCxGC-TOFMS method was optimized for multiresidue analysis of pesticides using a combination of a non-polar (RTX-5MS, 10 m x 0.18 mm x 0.2 microm) and a polar capillary column (TR-50MS, 1 m x 0.

Sorption of thiamethoxam in three Indian soils.

The sorption behavior of the insecticide thiamethoxam [3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine] on three Indian soils with different physico-chemical properties was investigated. The soils represent the major grapevine growing areas of India, where the vineyards frequently receive thiamethoxam applications as foliar spray, soil drenching and through drip irrigation for the management of various insect pests. The rate constants for adsorption and desorption at two different temperatures were obtained from the Lindstrom model, which simultaneously evaluated adsorption and desorption kinetics.

Degradation kinetics and safety evaluation of tetraconazole and difenoconazole residues in grape.

Background: Tetraconazole and difenoconazole are triazole fungicides with proven bioefficacy against grapevine powdery mildew disease. In the present work, the authors explored the residue dynamics of these two compounds in grapes and determined their preharvest intervals (PHIs) corresponding to multiple field applications at recommended and double rates considering the most critical use pattern in Indian viticulture. A confirmatory residue analysis method was validated for trace-level determination of both the compounds.

Sorption behaviour of forchlorfenuron in soil.

Adsorption of forchlorfenuron on three Indian soils reached equilibrium within 48 h with rate of adsorption being highest on sandy-loam followed by clay and silty-clay soils. The relative adsorptivity of the test soils could be attributed to the different organic matter and clay contents. Desorption rate followed the reverse trend.

Validation and uncertainty analysis of a multi-residue method for pesticides in grapes using ethyl acetate extraction and liquid chromatography-tandem mass spectrometry.

A method was validated for the multi-residue analysis of 82 pesticides in grapes at View Article and Find Full Text PDF

Rate of degradation of lambda-cyhalothrin and methomyl in grapes (Vitis vinifera L.).

Rates of degradation of lambda-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 lambda-cyhalothrin were lost with pre-harvest intervals (PHI) of 12.