Reverse phase liquid chromatographic determination of sulfathiazole residues in honey

Sulfathiazole residues were extracted from honey by homogenizing samples in acetone, filtering, and then evaporating the acetone under nitrogen at 40 degrees C. The remaining extract was transferred to a separatory funnel with 1N HCl and ethyl ether. An aliquot of the retained acid layer was screened by using the Bratton-Marshall reaction. If the test was positive, the remaining portion was analyzed directly through a mu Bondapak phenyl column monitored by a UV detector at 254 nm. The mobile phase was potassium phosphate monobasic in 10% acetonitrile adjusted to pH 3.0. Time for elution was 13 min. Average recoveries were 78% at the 0.1 ppm spiking level and 68% at the 1.0 ppm level. The minimum detectable amount was 0.06 ppm based on a spiked sample extract.