Specific polyclonal-based immunoassays for sulfathiazole

A highly sensitive and specific enzyme-linked immunosorbent assay has been developed for detection of sulfathiazole (STZ, 4-amino-N-thiazol-2-yl-benzene-sulfonamide). A set of haptens was synthesized in order to produce polyclonal antibodies against sulfonamides. Two ELISA formats (antibody-coated and conjugate-coated) were also investigated using all the serum/coating conjugate combinations that showed specific recognition. The developed ELISA succeeded in detection of STZ at concentrations as low as 0.03 ng mL(-1) over a measurable range of 0.12-6.71 ng mL(-1). Selectivity studies have demonstrated that other sulfonamides do not interfere significantly (< 10%) with analysis of STZ by this immunochemical technique. Analysis of spiked bee honey samples by the developed ELISA method showed recoveries were good. The selectivity and sensitivity (IC50 = 1.6 ng mL(-1)) make it a suitable screening method for determination of low levels of STZ in food samples.