Bestimmung von Carbamatpesticiden in Obst und Gem�se unter Verwendung der Hochdruckfl�ssigkeitschromatographie

Abstract

It is shown that carbamate pesticides can be determined at the ppm level in different kinds of fruits and vegetables using high pressure liquid chromatography. The lower detection limit corresponding to a signal to noise ratio of three is between 0,025 and 0,25 ppm depending on the type of carbamate and plant material. In all cases it is below the maximum permissible value for pesticide residues. Due to the high separating power of high pressure liquid chromatography a simple sample pretreatment procedure can be used. The carbamates are extracted from the biological sample by dichloromethane and injected directly into the liquid chromatograph after replacing the extraction solvent by the mobile phase. In many cases a definite identification and quantitation of the carbamate is possible with a single chromatographic column. Some plants with a more complex matrix require a two-column operation in which the effluent fraction of the first column containing the pesticide is transferred by column switching to a second column in order to achieve a complete separation. The improved resolution in the two-column operation is caused by the relative enrichment effect of the fractionation and the increased column length.

Comprehensive Off-Line, Two-Dimensional Liquid Chromatography. Application to the Separation of Peptide Digests

“…Two-dimensional chromatography was first used successfully by Consden et al, who separated the 22 proteinic amino acids by 2D paper chromatography . Later, complex mixtures were analyzed by combining two gas chromatographic separations, collecting selected fractions at the exit of a first column, and injecting an aliquot of these fractions onto a second column. − This approach was later improved by combining two columns in such a way that the whole sample injected into the first column migrates also through the second column. First developed and used in gas chromatography, − this approach was extended to HPLC. − Numerous applications to separations of complex mixtures encountered in food and polymer analyses and in the biotechnology and life sciences have been recently described. − Considerable interest and abundant theoretical discussions are devoted to the various problems raised by the concepts, designs, implementations, parameter selection, and optimization involved in this area of the separation sciences. ,− Probably the most critical issues to address in the implementation of a multidimensional scheme is the selection of the separation mechanisms that must be nearly independent .…”

Application of multiresidue procedures in pesticides residues analysis

“…In residue analysis, the use of IIPLC is particularly useful for pesticides which are not directly amenable to GLC determination, such as those that lack thermal stability, e.g. methylcarbamate insecticides (73,74,75) or phenylurea herbicides (76,77); cannot be analysed directly (phenoxyacetic acids, 78) or are not sufficiently volatile (e.g. some benzimidazole fungicides, 79,80) without further derivatisation.…”