Determination of piperacillin and mezlocillin in human serum and urine by high-performance liquid chromatography after derivatisation with 1,2,4-triazole

High-performance liquid chromatographic methods have been developed for the determination of piperacillin and mezlocillin in human serum and urine samples. The methods involve ultrafiltration of samples followed by reaction with 1.5 M 1,2,4-triazole and 0.5.10(-3) M mercury(II) chloride in solution (pH 8.50) at 50 degrees C for 15 min. The resulting products were separated on a C-18 column following stabilisation in an eluent containing sodium thiosulphate. They were detected at 323 nm for both penicillins. The methods have been applied to assays of these penicillins in human serum and urine samples. The procedures, which permit the determination of penicillin concentration down to 0.1 mu g ml(-1) in serum and 1 mu g ml(-1) in urine samples, are specific to intact penicillins without interference from corresponding penicilloates [see J. Haginaka et al., Anal. Sci. 1 (1985) 73]. At concentrations of 1-500 mu g ml(-1) for each compound, the within-and between-day precisions were 1.8-4.8 and 3.7-6.9, respectively. The accuracy was ca. 100% for all samples assayed. (C) 1998 Published by Elsevier Science B.V. All rights reserved.