GLC of Cycloserine

A GLC assay is described for cycloserine (D-4-amino-3-isoxazolidinone). The sample is dissolved in pyridine-water (2:1), an aliquot is evaporated, and the residue is treated with N,O-bis-(trimethylsilyl)acetamide and trimethylchlorosilane. After heating for a few minutes, chromatography is performed using a column containing methyl vinyl silicone, a relatively nonpolar liquid phase. Favorable quantitation is achieved by using hexamethylbenzene as the internal standard. The observed peak is the N,N′-bistri-methylsilyl derivative of cyloserine. The procedure eliminates interference from the cycloserine dimer, which does not chromatograph under these conditions.