Liquid chromatographic assay using a microcolumn coupled to a U-shaped optical cell for high-sensitivity ultraviolet absorbance detection of oxcarbazepine and its major metabolite in microdialysates.

An isocratic LC assay using a microcolumn (800 microns I.D.) coupled to a U-shaped optical flow cell (cell volume 70 nl; optical path length 8 mm) for high-sensitivity UV absorbance is described for the detection of oxcarbazepine and its major and active metabolite, 10,11-dihydro-10-hydroxycarbamazepine in microdialysates. Using the combination microcolumn-capillary UV detector, a ten-fold increase in sensitivity was obtained resulting in a limit of detection of 10 pg/10 microliters. This assay is sufficiently sensitive to allow quantification of drug and metabolite in 10-microliters aliquots of rat blood and hippocampus microdialysates, using carbamazepine-10,11-epoxide as external standard.