USEFULNESS OF ENZYME-IMMUNOASSAY (EIA) AS AN ANALYTICAL METHOD OF SULFAMETHOXAZOLE RESIDUES IN ANIMAL-TISSUES

Applicability of enzyme immunoassay (EIA) for determination of drug re sidues in animal tissues was examined by using sulfamethoxazole (SMX) as a test drug. EIA of SMX was specific for SMX, though N4-acetyl SMX showed a higher reactivity in the system. Control swine serum and plas ma spiked with 8 ng/ml SMX were negative. Control liver or other tissu es showed reactivity consistent with that expected when spiked with up to 25 ng/g (ml) SMX. It seems necessary for the accurate determinatio n of SMX in tissues to use standard curves prepared by adding SMX to c ontrol tissues, and in some cases by use of HPLC as well. EIA was howe ver, applicable as a screening method to detect SMX in chicken muscle without using control muscle when an adequate cut-off value was used.