Development and Validation of an Immunoaffinity Column for Detection of Aflatoxins in Agricultural Produce

Introduction:  Aflatoxins are recognized as the most important group of mycotoxins. They are naturally synthesized by a few Aspergillus species, mainly A. flavus and A. parasiticus.  There are several aflatoxins; types B₁, B₂, G₁ and G₂ are most common.  Aflatoxin B₁ is considered the most toxic and carcinogenic substance produced in nature. FDA has established action levels for the amount of aflatoxin allowed in food or feed to protect human and animal health.

Purpose:  To develop and validate immunoaffinity columns for accurate and reliable detection of aflatoxin in different food matrixes.

Methods:  The immunoaffinity column was prepared by attaching high affinity monoclonal antibodies against aflatoxin to agarose matrix in the column. The optimal amount of antibodies to use and the buffer system were developed. Performance of immunocolumns was evaluated as percent of aflatoxin recovery from spiked food matrices such as corn, peanuts and almonds. Aflatoxin was spiked into the sample extraction solution at concentrations ranging from 2 to 120 ppb, processed and tested by HPLC according to the AOAC Official Method 991.31 (JL Analytical Services Test Method SOP#: 3A00150, Ver. 14).  The performance of the immunocolumns was compared with that of the VICAM AflaTest WB SR (the currently AOAC approved product) on spiked as well as field samples.

Results:  Immunoaffinity columns were developed for accurate and reliable aflatoxin detection in different food matrices. Based on 35 samples spiked with 8 ppb of aflatoxin, the mean percent recovery of IEH AflaColumns was 90.58%, with a standard deviation of 4.54 and recovery range of 84-100%. This values compared favorably against those obtained when using VICAM AflaTest columns.

Significance:  We developed and validated an improved immunoaffinity method for aflatoxin detection in different food matrices.