Development of a screening method for five sulfonamides in salmon muscle tissue using thin-layer chromatography

A thin-layer chromatographic (TLC) method was developed for the analysis of five sulfonamides [sulfadiazine (SDZ), sulfamerazine (SMRZ), sulfamethazine (SMTZ), sulfadimethoxine (SDMX) and sulfapyridine (SP)] in salmon muscle tissue. "Matrix solid-phase dispersion" was employed whereby the tissue sample was ground with C18-derivatized silica gel. This material was packed into a column and washed with 10% toluene in hexane (discarded) followed by dichloromethane which was evaporated. The residue was chromatographed on a high-performance TLC plate using ethyl acetate-n-butanol-methanol-aqueous ammonia (35:45:15:2, v/v). Sulfonamides were detected after spraying the plate with a solution of fluorescamine. Method parameters were determined by analyzing spiked salmon muscle tissue samples. The method detection limits at the 99% confidence level were 0.11, 0.44, 0.07, 0.13 and 0.13 ppm for SDZ, SMRZ, SMTZ, SDMX and SP, respectively. The lowest-detectable levels were approximately 0.04 ppm for SDZ, SMTZ, SDMX and SP, and 0.10 ppm for SMRZ. The average recoveries of analyses were 61, 63, 60, 63 and 57% for SDZ, SMRZ, SMTZ, SDMX and SP, respectively, and were found to be analyst-dependent. The method was found to give linear detector responses for all analytes over spiking levels ranging from 0 to 2 ppm.