Supercritical fluid extraction of sulphamethazine and its metabolites from meat tissues.

An investigation is reported of factors affecting the supercritical fluid extraction of sulphamethazine and five of its metabolites from spiked meat (swine liver and kidney). The addition of the polar modifier methanol to the carbon dioxide extracting fluid was found to generally enhance recoveries under subcritical and supercritical conditions. Recoveries of the ionic metabolites were increased by up to 72% when employing tetramethylammonium hydroxide for ion pairing in situ with the supercritical fluid extraction. Extraction efficiency is demonstrated to be dependent on the matrix. Extractions of the less polar compounds from the kidney are more successful than from the liver, which corresponds to their partitioning into the supercritical fluid and/or the greater fraction of highly extractable fatty materials. The kidney was more retentive than liver for the relatively more polar compounds, which suggests that the liver offers a less polar environment under the same extraction conditions.