Tosylsarcosine-d3 is an intermediate in the synthesis of Creatinine-d3 (C781502), which is a labelled Creatinine. The end product of creatine catabolism. Normal constituent of urine. Also found together with creatine in muscle tissues and blood. Occurs in all soils and in grain seeds and other vegetable matter. Has been found in certain fish and in crab meat extract.