Determination of carbaryl, carbofuran and methiocarb in cucumbers and strawberries by monoclonal enzyme immunoassays and high-performance liquid chromatography with fluorescence detection - An analytical comparison

Carbaryl, carbofuran and methiocarb are three of the most important N-methy lcarbamate pesticides. In the present work, the application of laboratory-d eveloped monoclonal antibody-based enzyme-linked immunosorbent assays (ELIS As) to the determination of these compounds in fruits and vegetables is des cribed. Cucumbers and strawberries were spiked with the three carbamates at 10, 50 and 200 ppb. After extraction and clean-up, samples were analyzed b y immunoassay and by HPLC with post-column derivatization and fluorescence detection (US Environmental Protection Agency Method 531.1). Results obtain ed by ELISA correlated well with those obtained by HPLC, both in terms of a ccuracy and precision. Recoveries were in the 60-90% range by ELISA and in the 50-90% range by HPLC, depending on the particular combination of commod ity, pesticide, and fortification level under consideration. ELISAs were al so applied to the analysis of non-purified sample extracts with excellent r esults: recoveries close to 100% were obtained, while maintaining similar p recision values, This approach avoids the use of solid-phase extraction col umns, saves time, and considerably increases the sample throughput. Results clearly indicate that the developed immunoassays may be suitable for the q uantitative and reliable determination of carbaryl, carbofuran and methioca rb in fruits and vegetables even without including clean-up steps. These co nsiderations make these ELISAs very useful analytical tools for monitoring and regulatory programs, without the need of complex and expensive instrume ntation. (C) 1999 Elsevier Science B.V. All rights reserved.