Microbore Liquid Chromatography for Pediatric and Neonatal Therapeutic Drug Monitoring and Toxicology: Clinical Analysis of Chloramphenicol

Abstract

Microbore liquid chromatographic assay of chloramphenicol was developed, using 5 uL samples and reversed-phase liquid chromatographic analysis with a C-18, 20% carbon load column. For protein precipitation, serum samples were mixed with 20 uL of methanolic internal standard solutions. After centrifugation, 0.5 uL aliquots were injected for analysis. Two procedures were evaluated: procedure A-column = C-18, 3 um, carbon load of 10%, mobile phase = acetate/acetonitrile/tetrahydrofuran (85:15:1.5), flow rate = 80 uL/min, temperature = 50°C; procedure B-column = C-18, 5 um, carbon load of 20%, mobile phase = acetate/ acetonitrile(8:2), and flow rate = 60 uL/min. Procedure B was chosen for clinical efficacy study. The retention volumes of chloramphenicol and internal standard were 360 and 840 uL respectively. Calibration curve was linear between 3 to 40 mg/L. And day-to-day coefficient of variation was 6.8%. Correlation study with an established clinical liquid chromatographic assay for 20 patient samples showed acceptable data: r=0.9949, slope=0.9760 and intercept=0.0025. Selected drugs did not interfere. This assay, with advantages of small sample size, easy preparation and MBLC analysis, may be readily adapted for pediatric and neonatal drug monitoring.