A rapid quantitative lateral flow test for the detection of total aflatoxins in maize

Abstract

IntroductionAflatoxins (B1, B2, G1 and G2) are toxic secondary metabolites of, primarily, the fungi Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are potent carcinogens which cause liver diseases in livestock, domestic animals and humans throughout the world. Regulations for aflatoxins in commodities and food exist in more than 100 countries. A rapid quantitative lateral flow test, namely “Agrastrip”, was developed to measure total aflatoxin levels in maize. The test is developed based on the competitive immuno-chromatography principle. The total assay time for a sample extract is approximately 5 minutes. The results from the test are comparable to the reference HPLC or LC-MS/MS methods. ObjectiveTo validate the quantitative AgraStrip total aflatoxin test in maize samples. MethodsAflatoxins were extracted from ground maize sample using 70% methanol. To start an assay, buffer was added into a microwell to dissolve the pre-coated antibody-colloidal gold conjugate particle in the microwell. This was followed by mixing the dissolved conjugate with sample extract. A test strip was then placed into the mixture in microwell and incubated in a heat block incubator for 3 minutes. The test line zone in the test strip is able to capture the conjugate and form a visible line. The concentration of aflatoxins present in the sample is inversely proportional to the colour intensity of the test line. A line is always visible in positive control zone regardless of the presence of aflatoxins. The test strip is analyzed by the AgraVision® Reader and concentration of aflatoxins is determined. Results & DiscussionThe test was able to measure aflatoxins in the range of 5–100μg/kg. Limit of detection for the test kit on corn sample was 3.6μg/kg. Accuracy and precision of the test on maize sample naturally contaminated with aflatoxins were comparable to the results form reference HPLC or LC-MS/MS methods. The shelf-life of the test kit was 12 months. ConclusionAgrastrip total aflatoxin test is able to screen total aflatoxins in maize samples in its quantitation range.