[Gas chromatographic determination of S-methylmethionine (vitamin U) in plants].

A quantitative gas-chromatographic method to assay S-methyl methionine (vitamin U) in plants has been developed. The method is based on the disintegration of S-methyl methionine in the alkaline medium to form equimolecular quantities of dimethyl sulphide and homoserine. Dimethyl sulphide is distilled in the flow of an inert gas (nitrogen) and trapped in the toluene trap cooled to--78 degrees. The toluene solution containing dimethyl sulphide and carbon tetrachloride as an inner reference is analyzed in a gas chromatograph. Optimal conditions for the reaction to form 91.1% dimethyl sulphide from S-methyl methionine sulphonium chloirde at concentrations ranging from 0.1--5.0 mg% have been established. The standard error of measurements is +/- 1.5%.