Methiocarb residues in grapes and wine and their fate during vinification

Abstract

An analytical method developed for the determination of total methiocarb residues on grapes included initial extraction with acetonitrile, oxidation of residues to methiocarb sulfone with m-chloroperbenzoic acid, derivatization with methanesulfonyl chloride, and quantitation by sulfur pecific flame photometric gas chromatography. Grape juice, pomace, and wine were analyzed to determine the fate of methiocarb during vinification. Samples were also analyzed for the individual metabolites of methiocarb by using similar methods but omitting the oxidation step. Total residue on Pinot noir grapes treated 4 times at 4.5 kg /ha was 46 ppm 7 days after a handgun application and 7.4 ppm if the material was applied by airplane. Residues on White Riesling grapes treated with a concentrate sprayer at the same rate ranged from 12 to 19 ppm 7 days after last application. About 50-80% of the residue on fruit was removed from the vinification process with pomace and additional reductions occurred during the settling of juice. Total residue in wines made from grapes treated 7 days before harvest was 4.9 ppm in White Riesling wine and 4.6 ppm in Pinot noir wine which represented 26 and 13% of the initial residue on grapes.

Evolution of Residual Levels of Six Pesticides during Elaboration of Red Wines. Effect of Wine-Making Procedures in Their Dissappearance

“…In bibliographical references some contradictions exist on the influence of this wine-making step in the elimination of residues. In this way, Flori et al (1982a) andCabras et al (1986) indicate that there is a loss in maceration for vinclozolin, metalaxyl, penconazole, and fenarimol, whereas other authors (Miller et al, 1985;Cabras et al, 1995) conclude that for methiocarb and some organophosphorus insecticides (chlorpyrifos, methidation, quinalphos, and parathion-methyl) do not exist significant differences when the maceration is or is not carried.…”

Food processing a tool to pesticide residue dissipation – A review

“…About 50-80% of the residue on fruit was removed from the vinification process with pomace and additional reductions occurred during the settling of juice. Total residues in wines made from grapes treated seven days before harvest was 4.9 ppm in wine which represented 26% of the initial residues on grapes (Miller, Kiigemagi, Thomson, Heatherball, & Deinzer, 1985).…”

Hapten Synthesis and Production of Monoclonal Antibodies to the N-Methylcarbamate Pesticide Methiocarb

“…Methiocarb hydrolyzes quite rapidly in water under natural sunlight to afford 4-(methylthio)-3,5-xylenol (Chiron et al, 1996). In plants, methiocarb is metabolized to its sulfoxide and sulfone derivatives (Miller et al, 1985). Like the parent compound, methiocarb sulfoxide and methiocarb sulfone are cholinesterase inhibitors.…”