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Free and conjugated sulfonamides are extracted from edible animal tissue with acetone. Carbohydrate "is precipitated and removed, and the acetone is evaporated. The residue is transferred to a separatory funnel with ethyl ether and 17V HC1. The acid layer is drawn off and a portion of the 17V HC1 is screened, using the Bratton-Marshall reaction. If this portion is positive, the remaining portion is buffered to pH 6.5 and extracted with methylene chloride. The residue is methylated with diazomethane and then acylated with pentafluoropropionic anhydride. The resulting derivatives are detected by gas-liquid chromatography, using electron capture (63Ni) detection and a column packed with 3% OV-17 on Gas-Chrom Q. This method has been validated by recovering sulfathiazole, sulfachloropyrazine, sulfamethazine, sulfadimethoxine, and sulfabromomethazine from liver, kidney, and muscle at levels of 0.1, 0.5, and 1.0 ppm. The 5 sulfonamides were recovered in excess of 60%, with an average mean recovery of 81.5% at the 0.1 ppm level, 79.1% at the 0.5 ppm level, and 76.0% at the 1.0 ppm level.

Dried citrus waste was fed to dairy cows, their milk was extracted, and aflatoxin M1 was quantitated by using both high pressure liquid chromatography (HPLC) and thin layer chromatography (TLC). Results indicate that a compound from the citrus waste, which is excreted into the milk, interferes with the HPLC determination of aflatoxin M1 in milk and causes a false positive test. This interference can be overcome by using TLC with proper selection of developing solvents.

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