HIGH-PRESSURE LIQUID-CHROMATOGRAPHY DETECTION OF THE ANTI-THYROID COMPOUND 5-VINYLOXAZOLIDINE-2-THIONE IN MILK

A method is described for the analysis in milk of low levels of the goitrogen 5-vinyloxazolidine-2-thione (OZT), a hydrolytic product of a glucosinolate present in some rapeseed meal used in animal feed. Milk at pH 8.5 was treated with hydrogen sulfide prior to extraction with diethyl ether. The residue obtained from the ether extract was reextracted with hexane-water (pH 7) and recovered from the aqueous phase (pH 8.5) using diethyl ether. The OZT in the ether residue was separated by high-pressure liquid chromatography on a Lichrosorb Si60 (5 µm) column in isooctane containing 10% isopropyl alcohol and 0.1% ammonium hydroxide. The absorption was measured at 254 nm. Less than 2 µg of OZT per liter of milk can be detected on a relatively small sample (50 mL). OZT was not detected in winter milk from two dairies in Manitoba, Saskatchewan, and Alberta and three dairies in Ontario. © 1979, American Chemical Society. All rights reserved.