Consumption of asparagus is known to produce a characteristic odor in urine.It has been shown that the cause of the odor is primarily due to the presence of methanethiol, dimethyl sulphide, dimethyl disulphide, dimethyl sulphoxide and dimethyl sulphone.These compounds are believed to be derived from two S-methyl thioesters, S-methyl thioacrylate and S-methyl 3-(methylthio)thiopropionate.These are in turn believed to be dervived from asparagusic acid and dihydroasparagusic acid, which are unique to asparagus.Previous work to determine these components has been done by using solvent extraction, over a period of 48 hours, in either ethyl ether or methylene chloride, followed with analysis by GC-MS.During the extraction process, the sample is heated to above body temperature, which can lead to chemical alterations of compounds in the urine.