Chronic barbiturate treatment increases NMDA receptors but decreases kainate receptors in mouse cortex

Glycyrrhizin is the main component of glycyrrhiza. In this article an Ion-pair high performance liquid chromatography (HPLC) method is described for the determination of glycyrrhizin in two kinds of glycyrrhiza from different origins and twelve kinds of Chinese traditional patent medicine containing glycyrrhiza. A reversed phase system was used, including an ODS column with water and methanol (36:64) as the mobile phase which contained 5mmol/L tetra-n-butyl ammonium hydroxide and was adjusted to pH 6.0 by phosphoric acid. The column temperature was 35 degrees C; the detection was performed at 254 nm. Under this condition glycyrrhizin could be separated from other components. The limit of detection was 13ng, and the average recovery was 99.85%. During the experiments, we studied the concentration of counter-ion, the mixing ratio of methanol to water, the pH of the mobile phase and column temperature and their effect on the capacity factor of compound and resolution. We also studied the method of pre-treatment for the samples. The determination method is simple and accurate.