Use of a Small-Bore Internal-Surface Reversed-Phase Silica Column for the Micro High-Performance Frontal Analysis of Carbamazepine in an Albumin Solution with a Small Sample Volume

摘要

A micro high-performance frontal analysis (MHPFA) using a small-bore internal-surface reversed-phase silica column (10cm×1.0mm or 1.5mm id.) was developed for the simultaneous determination of the total and unbound carbamazepine (CBZ) concentrations in a human serum albumin (HSA) solution. When a 100-μl or 200-μl portion of a 4-12μg/ml CBZ solution containing 593μM HSA was directly injected into the column, CBZ gave a trapezoidal peakwith the plateau being separated from the HSA peak. The CBZ concentration, calculated from the plateau height, agreed well with the unbound drug concentration determined by the conventional ultrafiltration-HPLC method, and the CBZ concentration calculated from the peak area coincided with the total concentration. The reproducibility was satisfactory (RSD, 3.79%, n=5 or 6). The use of a glass-lined stainless-steel column and an injector-reswitchingtechnique, which prevents the introduction of a diffused portion of the sample solution into the column, was necessary for a frontal analysis using these small-bore columns. The present MHPFA reduced the sample volume to as low as one-seventh of that required for HPFA using an internal-surface reversed-phase silica column of conventional size (15cm×4.6mm i.d.).