A fast, specific, sensitive high-performance liquid chromatographic method for the determination of cefmetazole in human serum was developed. The serum samples were deproteinized by adding 5% trichloroacetic acid in methanol containing barbital as an internal standard and were injected onto a reverse-phase column (mu-Bondapak C18) with a mobile phase of 10 to 15% acetonitrile in 0.005 M citrate buffer (pH 5.4). Eluted components were detected by UV absorption at 254 nm. Cefmetazole and the internal standard were separated from interfering serum components by this method. The peak height ratio of cefmetazole to the internal standard was proportional to the cefmetazole concentration in the range from 0.4 to 100 micrograms/ml. Serum samples obtained from three patients after a single intravenous injection of cefmetazole were assayed by this method and by a microbiological method. There was a good correlation between two assay methods (correlation, coefficient, 0.98). The stability of cefmetazole in human serum was (correlation coefficient, 0.98). The stability of cefmetazole in human serum was also determined by this method. Cefmetazole was stable in human serum for 2 weeks at 4 degrees C or for at least 8 weeks if it was kept frozen. As the high-performance liquid chromatography method is simple, specific, accurate, and reproducible, it appears to be more suitable for routine assay of cephalosporins than other assay methods.
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