An Experimental Design Approach to the Optimization of Supercritical Fluid Extraction for the Determination of Oil and Grease in Soil

The objective of this study was to examine the extension of supercritical fluid extraction (SFE) to the extraction of polar drugs. The ultimate aim was to extract veterinary residues from food animal products and thereby demonstrate the versatility of SFE. This technique is shown to have many facets that require careful thought and understanding if it is to be successfully used. Our initial studies indicate that polar drugs may be readily solubilized from relatively inert matrices such as sand, with high recoveries and very little discrimination between related compounds while using only moderate extraction conditions and times. SFE of the same drugs from spiked chicken liver and swine muscle is significantly more difficult and requires more drastic conditions. Close to complete recoveries are achieved for some drugs, while considerably less is found in the worst case. For sulphamerazine, sulphamethizole, sulphamethazine, sulphamethoxypyridazine, sulphamethoxazole, and the major metabolite N4-acetyl-sulphamethoxazole, the recoveries are 97, 66, 94, 79, 53, and 65%, respectively, from spiked liver and 95, 27, 86, 91, 96 and 70%, respectively, from spiked swine muscle. Incurred sulphamethazine is recovered from swine muscle in good general agreement with the reference values provided.