Determination of fluopicolide in grapes and soil using an easy sample preparation method and gas chromatography-mass spectrometry

A simple analytical method was developed and validated to determine fluopicolide residues in grapes and soil using the “Quick, Easy, Cheap, Effective, Rugged and Safe” approach followed by gas chromatography-mass spectrometry in the selected ion monitoring mode. Fluopicolide residues were extracted from grape and soil samples with acetonitrile, and the extracts were cleaned up by dispersive solid-phase extraction with primary secondary amine sorbent. The limit of quantification was 0.02 mg kg^?1 with grape and soil samples spiked at three levels, and recoveries were from 95% to 101% and 94% to 101% with relative standard deviations from 0.2% to 4.4%. The method is less expensive and safer than existing analytical methods for grapes and soil.     

Pyrimethanil Residues on Table Grapes Italia after Field Treatment

Residues of the pyrimidine fungicide pyrimethanil [N-(4,6-dimethylpyrimidin-2yl)aniline] were determined in table grapes “Italia” by gas chromatography nitrogen-phosphorus detector (GC-NPD). Pesticides were extracted from grapes with ethyl acetate and hexane solution (1:1 v/v), and were analyzed without any further clean up. Pyrimethanil was confirmed by high-performance liquid chromatography (HPLC) fitted with a diode array detector (DAD) and electrospray ionization mass spectrometry (ESI-MS) in the select ion-monitoring mode (SIM). The residue of pyrimethanil was under the legal limit immediately after treatment, and showed a half-life time, calculated as a reaction of pseudo first order, of 12 days, with a regression coefficient of 0.9954. Recoveries from fortified grapes ranged between 90 and 113% with a maximum coefficient of variation (CV) of 11%. The calculated limits of detection and quantitation for pyrimethanil were 0.005 and 0.01 mg/kg, respectively.     

Comparison of gas chromatography and immunoassay methods in quantifying fenitrothion residues in grape juice processed into alcoholic drinks

Abstract

Wine and Arak, the national alcoholic drink in Lebanon, were prepared from grape juice fortified with fenitrothion to a concentration of 20ppm. Samples of the 11 fractions produced by the fermentation and distillation steps were analyzed for fenitrothion residues using gas chromatography (GC) and enzyme‐linked immunosorbent assay (ELISA). Results of residue analyses showed that the two techniques were highly correlated (r = 0.978) and indicated that fenitrothion was stable during the fermentation steps but not during distillation. The clarified wine 35 days later contained about 85% (15.3 ppm) of the fenitrothion concentration found in the juice as determined by GC analysis. Arak was prepared by a two‐steps distillation of the clarified wine. The alcohol distillate and undistilled fraction from the first distillation contained 2.5 ppm and 5.8 ppm of fenitrothion, respectively. No fenitrothion residues were detected by both techniques in the four fractions collected from the second distillation step.     

Behavior of dialifor,dimethoate, and methidathion in artificially fortified grape juice processed into wine

Abstract

Dialifor and methidathion were added to diluted “Zinfandel”; grape concentrate at 25 ppm and dimethoate at 1.0 and 25 ppm prior to fermentation with Saccharomyces cerevisiae. The finished wine 56 days later contained 10% (2.5 ppm) of the dialifor, 46% (12 ppm) of the methidathion and 85% (21 and 0.98 ppm) of the dimethoate added to the grape must. Residues in wine stored at 24°C dissipated by hydrolysis; half‐lives in wine were 7 days for dialifor and methidathion and 30 days for dimethoate. Residues were unchanged in wine in frozen storage for one year. Analysis of seven commercial wines for dimethoate indicated less than 0.03 ppm dimethoate was present; identity could not be confirmed by thin‐layer chromatography at this level.