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 Original Research Article

The insecticide carbaryl was quantified in fruit and vegetable juices obtained 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 the pH of the final solution to the optimum value (pH ∼7.5), in case of citric samples. The similarity and parallelism between the standard curves obtained from the diluted crop juices and the assay buffer indicate that the matrix interference is minimal for most samples. Limits of detection, calculated at the pesticide concentration giving 90% of the B0 (working range), varied from 0.13 to 6.05 μg l−1 in the crop juices. Accuracy of carbaryl ELISA method from crops spiked at 10 and 100 μg l−1 was comparable to liquid chromatography–postcolumn fluorescence method. Recoveries averaged 95% (85–108%) for immunoassays and 103% (100–106%) for LC analysis.