Direct application of an enzyme-linked immunosorbent assay method for carbaryl determination in fruits and vegetables. Comparison with a liquid chromatography-postcolumn reaction fluorescence detection method

The insecticide carbaryl was quantified in fruit and vegetable juices obtai ned from seven crops without any previous treatment. A previously developed enzyme-linked immunosorbent assay (ELISA) was applied by simply analysing the fruit and vegetable juices diluted in the buffer assay and adjusting th e pH of the final solution to the optimum value (pH similar to 7.5), in cas e of citric samples. The similarity and parallelism between the standard cu rves obtained from the diluted crop juices and the assay buffer indicate th at the matrix interference is minimal for most samples. Limits of detection , calculated at the pesticide concentration giving 90% of the B-0 (working range), varied from 0.13 to 6.05 mu g 1(-1) in the crop juices. Accuracy of carbaryl ELISA method from crops spiked at 10 and 100 mu g 1(-1) was compa rable to liquid chromatography-postcolumn fluorescence method. Recoveries a veraged 95% (85-108%) for immunoassays and 103% (100-106%) for LC analysis. (C) 1999 Elsevier Science B.V. All rights reserved.