Simplified multiresidue method for liquid chromatographic determination of N-methyl carbamate insecticides in fruits and vegetables

J Assoc Off Anal Chem. 1988 May-Jun;71(3):542-6.

Abstract

A simplified method is described for determining 7 N-methyl carbamates (aldicarb, carbaryl, carbofuran, methiocarb, methomyl, oxamyl, and propoxur) and 3 related metabolites (aldicarb sulfoxide, aldicarb sulfone, and 3-hydroxy carbofuran) in fruits and vegetables. Residues are extracted from crops with methanol; coextractives are then separated by gel permeation chromatography (GPC) or GPC with on-line Nuchar-Celite cleanup for crops with high chlorophyll and/or carotene content (e.g., cabbage and broccoli). Carbamates are separated on a reverse-phase liquid chromatography column, using a methanol-water gradient mobile phase. Separation is followed by postcolumn hydrolysis to yield methylamine, and the formation of a fluorophore with o-phthalaldehyde and 2-mercaptoethanol prior to fluorescence detection. Recovery data were obtained by fortifying 5 different crops (apples, broccoli, cabbages, cauliflower, and potatoes) at 0.05 and 0.5 ppm. Recoveries averaged 93% at both fortification levels except for the very polar aldicarb sulfoxide for which recoveries averaged around 52% at both levels. The coefficient of variation of the method at both levels is less than 5% and the limit of detection, defined at 5 times baseline noise, varies between 5 and 10 ppb, depending on the compound.

MeSH terms

  • Carbamates*
  • Chromatography, Gel
  • Chromatography, Liquid
  • Fruit / analysis*
  • Indicators and Reagents
  • Insecticides / analysis*
  • Pesticide Residues / analysis*
  • Spectrometry, Fluorescence
  • Vegetables / analysis*

Substances

  • Carbamates
  • Indicators and Reagents
  • Insecticides
  • Pesticide Residues