Usefulness of Semi-Micro High-Performance Liquid Chromatography Using Solid-Phase Extraction in Analysis of Serum Drug Concentration.

A new method for the analysis of pheytoin (DPH) and carbamazepine (CBZ) in human serum described. The method involves extraction of DPH and CBZ from serum by re-used solidphase extraction (SPE) column prior to a semi-micro high-performance liquid chromatographic analysis. The chromatography for the analysis of DPH at a level of 20μg/mL was complete in 5 using a semi-micro column (C 18, 2.0mm i.d.×15cm). The sensitivity of the analysis was 3.97-fold higher than that for conventional HPLC. DPH and CBZ were extracted from serum using commercially available SPE column (Isolute C 18), and analytical recovery rate of DPH and CBZ which were added to the serum (50μL) at 2.0, 5.0, 10.0, 20.0 and 40.0μg/mL, ranged from 83.5 to 94.0% and from 86.7 to 117.1%, respectively. Excellent recovery rates of DPH and CBZ in the serum were also obtained when the same SPE column was re-used over 30-times, protein and/or albumin hardly remained in the solid-phase of the re-used SPE column. There results indicate that this new method could reduce both the time need to perform each analysis the amount of sample needed due to high sensitivity. In addition, the method also demonstrated a good cost performance. Thus, the method might be highly useful to support drug monitoring and pharmacokinetic studies.