Analysis for Carbamate Insecticides and Metabolites

Abstract

Of the more conventional pesticidal chemicals, the carbamate insecticides pose some unique problems relative to residue analysis. Most of these compounds are unstable under conditions normally used for GLC analysis and require special attention if this technique is to apply to the carbamates. Moreover, the carbamates are commonly metabolized to products which are toxicologically significant and which must be included in any analytical considerations. These and other problems inherent in carbamate residue methodology are discussed in this report along with technique currently utilized or having potential as sound procedures for the analyses of carbamate insecticides.

Gas chromatographic determination of carbamate pesticides after flash-heater methylation with trimethylsulfonium hydroxide

“…Their thermolability complicates gas chromatographic (GC) determination by forming the corresponding phenols and other fragments in unreproducible amounts through thermal degradation inside the injector or during the GC run (Thier and Frehse, 1986). Such difficulties may be overcome by using special conditions (Hall and Harris, 1979;Dorough and Thorstenson, 1975) or by derivatization of either the intact substances or the phenols after complete hydrolysis (Greenhalgh and Kovacicova, 1975). Fishbein and Zielinski (1965) described the preparation of thermally stable trimethylsilyl derivatives of some carbamates.…”

Five-way ANOVA Interaction Analysis of the Selective Extraction of Carbaryl, Pirimicarb and Aldicarb From Soils by Supercritical Fluid Extraction

“…Due to the thermal lability of this class of compounds and consequent incompatibility with GC methods, previous work involving the analysis of carbamates has focused on the use of reverse phase C 18 liquid chromatography with both UV and fluorescence methods of detection. The derivatisation of the carbamates using 2,4-dinitrophenyl phenyl ether 1 or trichloroacetate 2 has also been used in this context with Dorough and Thorstenson 3 providing a thorough review on determining carbamates and their metabolites by GC. Previous work on alternative methods has included mass spectrometric detection (HPLC-thermospray-MS) 4 and 'spot-test' colorimetric reactions in off-line determinations.…”

Derivatization of several carbamate pesticides with methanesulfonyl chloride and detection by gas-liquid chromatography with the flame photometric detector: application to residues of carbaryl on lentil straw

“…Because direct analysis of carbamates by gas-liquid chromatography (GLC) is difficult (since most carbamate pesticides degrade on the GLC column), the most common approach is to hydrolyze the carbamate ester linkage and derivatize the resultant phenol with a chloro, fluoro, or bromo compound to yield a product that can be readily detected by a GLC equipped with an electron-capture detector (ECD). Many of these procedures are discussed in reviews by Williams (1971) and by Dorough and Thorstenson (1975).…”