DEVELOPMENT OF AN IMMUNOAFFINITY COLUMN AND AN INDIRECT IMMUNOASSAY WITH A BIOTIN STREPTAVIDIN DETECTION SYSTEM FOR AFLATOXIN M(1) IN MILK

A sensitive and rapid screening method for the estimation of aflatoxin M1 (AFM1) in milk has been developed. Milk samples were first purified by immunoaffinity chromatography (IAC) using polyclonal antibodies raised in rabbits against aflatoxin M1-bovine serum albumin (AFM1-BSA) and coupled to an activated sepharose matrix. The eluate was analyzed in an indirect competitive streptavidin-biotin modified enzyme linked immunoassay (EIA). Microtitre plates were coated with AFM1-BSA that competes with the analyte in the sample for binding with the biotinylated antibody. Bound biotinylated antibody was detected using a streptavidin biotinylated horseradish peroxidase complex. The limit of detection of the EIA is 2 ng kg-1. By combination of IAC and EIA, spiked milk samples were analyzed. In conclusion, IAC-EIA is a sensitive and rapid method for the estimation of AFM1 in milk.