Determination of plasma testosterone by mass fragmentography using [3,4-13C]testosterone as an internal standard

The combination of glass capillary gas chromatography--mass spectrometry is especially suitable for the recognition of compounds. The use of [3,4-13C]testosterone as internal standard, mass fragmentography and isotope ratio measurement have been applied to the quantitative determination of testosterone in plasma. This paper describes the method, using tert.-butyldimethylsilylmethoxime and di-heptafluorobutyrate derivatives. The calibration graph in isotopic dilution is examined. The results obtained are compared with the results obtained by radioimmunoassay. The sensitivity of the method is judged from the lower limit of detection: 4.5 pg. The precision, and inter- and intra-assay are calculated.