SPA enhanced FPIA-based detection of pesticide residue with ppb/ppt level detection limit.

Pesticide residue in fruits & vegetables is one of the key issues affecting the export of rural products in India. Pesticide exposure or intake causes major nervous system problems in children. The solutions to quantitate them in field are rare and the pesticide residue detection in the parts per billion (ppb) ranges is challenging. Except ELISA, none of the existing methods can detect pesticide residues in ppb range in the field. We employed a new approach of concentrating field samples and used sodium polyacrylate (SPA) as water absorbing material. The SPA beads concentrate the field samples and obtained a sub ppb range detection using an existing FPIA system and could improve overall sensitivity by 10-100 fold. The developed assay can be done in few seconds. We have used three pesticides 2,4-D, atrazine and methyl parathion with 0.1, 0.5 and 3 ppb detection limit respectively. We developed a simple field ready FPIA device and used sodium poly acrylate (SPA) in this biochemical FPIA to enhance sensitivity. Our tests with spiked field samples offers a possibility of using SPA concentration assisted FPIA in field. This study will have far reaching applications of both qualitative & quantitative analysis chemical analytes in field samples.