DETERMINATION OF SULFAMETHAZINE IN ANIMAL-TISSUES BY ENZYME-IMMUNOASSAY

An enzyme immunoassay for sulphamethazine was developed using an antiserum raised in rabbits by immunization against a sulphamethazine diazo derivative coupled to bovine serum albumin. Horseradish peroxidase coupled to sulphamethazine by a carbodiimide method was selected as a tracer. The dose of sulphamethazine that caused 50% binding inhibition was 3.8 ng per well with a 2-h incubation time at 37-degrees-C and 1.2 ng per well with a 16-h incubation time at 4-degrees-C. The assay was evaluated by using control and sulphamethazine-fortified muscle and liver samples. These samples were treated by the matrix solid-phase dispersion method for the subsequent isolation of the drug. The method allowed a detection limit well below the tolerance limit (0.1 mg kg-1) generally applied for sulphamethazine.