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in n-decane. The mass spectrometer employed was the Finnigan MATTSQ 70 and the separation was carried out on a BPX5 column 25 m long, 250 mm I.D. The column was operated isothermally at 150ûC for one minute, programmed at 5ûC per minute to 300ûC and then maintained at 300ûC for a further minute.   To follow the metabolic process, it was necessary to understand the basic nature of the fragmentation that was taking place in the mass spectrometer. In the electron ionization of the 17a-alkyl steroids the fragment pattern is dominated by the D-ring fragment ions. In the case of the fragmentation of 17a-methyltestosterone, the process involves the cleavage at the C13 to C17 bonds and at the C14 to C15 bonds.   This yields positively charged a, b-unsaturated ketone fragments at m/z 143. Consequently, observation of a pair of ions at m/z 143 and 146 in the EI mass spectra (the latter resulting from the labeled d3 steroids) is indicative that the D-ring is unaltered in the

the use of GC/MS for a wide variety of applications that have accumulated over nearly 50 years. GC/MS has been used extensively for forensic work, pollution studies quality control purposes and widely in all aspects of fundamental research. It is impossible to deal systematically with GC/MS applications in a simple monograph. Consequently, a few selected examples will be given to illustrate the versatiity of the technique and the more popular fields of application.   Analysis of Anabolic Steroids in Biological Materials An example of the use of the GC/MS system in metabolite studies is afforded by the work of Schoene et al. (19) who employed a GC/MS tandem instrument to examine the metabolism of 17a-alkyl anabolic steroids in horses after oral administration of the drugs. 100 mg of 17a-methyl testosterone together with the deuterated analog were fed to two horses via their normal food diet. Naturally voided urine was collected over 72 hours, 5 ml samples were extracted with

other technique if more appropriate. Chromatography Applications Gas chromatography has an entirely different field of applications to that of liquid chromatography. In general, gas chromatography is used for the separation of volatile materials and liquid chromatography for the separation of involatile liquids and solids. There are certain compounds, however, that can be separated with either techniques, and more importantly, many involatile substances such as amino acids, steroids and high molecular eight fatty acids can be derivatized to form volatile substances that can be separated by GC. The derivatization must be highly reproducible and usually proceed to completion in order to maintain adequate accuracy. The capillary columns in GC can have much higher efficiencies than their LC counterpart and thus GC can more easily handle multicomponent mixtures such as essential oils. On the other hand, only LC can separate the peptides, polypeptides, proteins

nbsp; It is clear, that the peaks depicted on the single ion monitoring chromatograms represent metabolites in which the D-ring has been preserved. This example illustrates how the GC/MS technique can be a valuable tool for following the metabolic processes associated with the 17a-alkyl anabolic steroids.   Analysis of Waxes and Lipid Type Materials   The metabolism of fatty acids in cell cultures can be very important, particularly with regard to cancer cells. The possible conversion of the fatty acids to peroxides and the role of these compounds in carcinogenesis is still not completely understood. To aid in this type of work Wallace and Coleman (20) developed a procedure for the fatty acid assay of cell tissue employing a GC/MS instrument. According to their publication,