Evaluation of a commercial immunoassay system for sulfamethazine and aflatoxin detection in biological fluids and...

Commercial immunoassay systems produced by International Diagnostics to analyze for sulfa drugs and aflatoxin residues have been evaluated with milk, urine, feed and serum samples. Neither system produced satisfactory results with feeds. The sulfa test reproducibility was good enough to provide semiquantitative results on milk (40 ul sample) and urine, but should be regarded as qualitative on urine or feed. The reproducibility of the aflatoxin test was acceptable for semiquantitative use on serum, but should be regarded as qualitative on urine and semiquantitative on milk with a solid phase concentration. The overall reproducibility was at least +/- 10% if the test was used semiquantitatively. The sensitivity of the test was 10 ng for both sulfamethazine and aflatoxin B1. The range of the color change was very narrow (0-20 ng). The aflatoxin test was designed for aflatoxin B1 and was roughly twice as sensitive to B1 as to M1 aflatoxin. These procedures can be used on appropriate matrices at suitable sensitivities to rapidly screen samples for sulfa drugs and aflatoxin residues. The use of proper standards to demonstrate effectiveness in each matrix is very important.