Thin Layer Chromatography - The Assay of Sulfamethazine in Pork Carcasses 1


The Assay of Sulfamethazine in Pork Carcasses


Sulfonamides in general are widely used as antibacterial agents in veterinary practice, and sulfamethazine (4-amino-N-(4-6-dimethyl-pyrimdin-2-yl) benzene-sulfonamide) is one that is frequently employed in pig husbandry.


Unfortunately, sulfamethazine can be potentially and easily misused; for example, if there is an inadequate withdrawal period prior to slaughter (i.e. time between administering the drug and killing), there may be a level of the drug in the meat that will exceeds the minimum allowed by law for human safety. It follows, that, a sensitive, rapid and simple on-site analytical procedure is necessary to ensure regulatory compliance. Shearan and O'Keeffe [11] developed a rapid analytical procedure with a TLC 'finish' that allowed the level of sulfamethazine to be determined as either below, above, or coincident with the statuary limit, at a relatively fast rate of 20 samples per day.


The extraction procedure was analogous to that developed by Shearan et al. [12]. 0.5 g of porcine tissue was blended with 2 g C18 reversed phase adsorbent in a mortar and pestle for 30-45 s. The blend was then packed into the syringe barrel of a solid phase extractor and the contents washed with 8 ml of hexane. The blend was then extracted with 8 ml of dichloromethane, the extract evaporated to dryness in a stream of nitrogen and the residue taken up in 100 ml of dichloromethane.