A rapid and efficient screening test is needed for the evaluation of
antibiotic residues in catfish tissues. Procedures were developed to determine the optimum R
processing of catfish tissues for use with the EZ Screen TestR kit method. EZ Screen
TestR system is commercially available and approved for use in the detection of SDM
in chicken products at the level of 0.1 ppm.
Catfish filet was spiked with sulfadimethoxine (SDM). Ten-fold and two-fold
serial dilutions of samples were prepared to determine the sensitivity of the test. EZ Screen
TestR system detected SDM in catfish filet at the level of 0.1 ppm by the ten-fold
dilution method. While using two-fold dilutions, EZ Screen TestR system detected SDM
level as low as 0.0125 ppm. In subsequent study, channel catfish were force-fed in a single or
double dose of Romet 30R comparable to 3% of their body weight for either 5 days or
10 days. Catfish filet were taken every day post-feeding for 14 days. There was no SDM detected
at the level of 0.1 ppm in filet from any of SDM-treated groups at and after 5 days
post-feeding. When data from EZ ScreenR. Test were compared to those from HPLC, EZ
Screen TestR had 100% sensitivity and 90% specificity. The results indicate that EZ
Screen TestR can be used to detect SDM residue in catfish fillet and may be applied
to the field samples.