Merck, T-070-1ML, Testosterone-2,3,4-¹³C₃ solution

A stable-labeled internal standard for monitoring serum testosterone levels in men, women, and children by LC-MS/MS. The Centers for Disease Control (CDC) Hormone Standardization Project cites Testosterone-2,3,4-¹³C₃ as the internal standard of choice for measurement of testosterone at low concentrations in biological fluids by LC-MS/MS. For these analyses, ¹³C-labeled internal standards can eliminate potential issues of isotopic exchange and minimize separation of later-eluting analytes from a higher substituted deuterium-labeled internal standard. Acetonitrile was chosen as diluent for its ease of handling and miscibility with water and biological specimens.