Enzyme-linked immunosorbent assay for the quantitation of the fungicide tetraconazole in fruits and fruit juices

An antibody-immobilized ELISA test for the detection of the triazole tetraconazole is described. The minimum detection limit was 2 ng/mL (ppb), and the linearity of the assay extended from 1.9 to 1000 ng/mL (ppb), with a variation of absorbance (Delta OD) of similar to 0.83 +/- 0.04. Good reproducibility and reliability of the ELISA assay was found for fruit commodities spiked with different amounts of tetraconazole. The effect of fruit matrices on the sensibility of the ELISA was investigated, and a matrix interference index (I-m) is proposed for quantitation of tetraconazole recovery in the analyzed fruit homogenates. Analysis of fruit juices was optimized to minimize matrix interference. This study could represent an approach for validation of ELISA tests for analysis of tetraconazole in fruit commodities and it should be adaptable to other food matrices.