Immunoanalysis of endosulphan residues in spices

ELISA based endosulfan assay was developed using antibodies raised against a hapten for endosulfan. The competitive assay formatted had a sensitivity of 14 ppb and the minimum detection level was 1.4 ppb. The application and efficiency of the assay was tested for the detection of residues in spices like red chillies (var. Byadagi), pepper and cardamom. For red chilli six different matrix clean-up approaches such as dilution, coagulation of matrices and adsorption florisil column were tested. Clean-up was not achieved by individual methods (IC 50 >100 ppb). A combination of dilution and coagulation methods improved the efficiency of the clean-up resulting in an IC 50 of 11-14 ppb. Spike and recovery studies were conducted and the recovery was 75-100%. For pepper, extraction with 65% acetonitrile appeared to be good while for cardamom a matrix effect was seen in all the extracts. Clean-up of matrices is yet to be achieved. The ELISA technique reported could be effectively used to alert endosulfan contamination in red chillies and pepper which have great export potential.