Analysis of thiol-containing compounds in biological samples by capillary zone electrophoresis

A new method for the determination of reduced and oxidized glutathione by using capillary zone electrophoresis was developed and compared with the N-(1-pyrenyl)maleimide high-performance liquid chromotography method. The tissue samples were obtained from C57BL/6 mice and homogenized in deionized water. The detection wavelength was set at 214 nm. A 50-cm effective length x 75 microns i.d. uncoated fused silica capillary with a 10 mM phosphate buffer at pH 7.5 was used for the experiment. Samples were introduced by pressure injection for 5s. The voltage for separation was at 20 kV. Between runs, the capillary was regularly washed with 0.1 N NaOH and deionized water, followed by reconditioning with running buffer. The present method was shown to be reproducible and is convenient in that a derivatization step is not required. The method has been used to measure glutathione levels in biological samples and the results show good agreement with those obtained by high-performance liquid chromotography.