A simple, economical and effective non-aqueous capillary electrophoresis separation and detection method was developed for the quantification of deoxyschizandrin and gamma-schizandrin in Schisandra chinensis Baill. and its medicinal preparations for the first time. After optimization of separation conditions, a buffer of 140 mmol/L sodium cholate in methanol was selected for separating the two analytes, but baseline separation of SA and SB in real samples was not obtained. Therefore second-order derivative electropherograms were applied for resolving overlapping peaks. Regression equations revealed good linear relationships (correlation coefficients 0.9975--0.9988) between peak heights in second-order derivative electropherograms and concentrations of the two analytes. The relative standard deviations (RSD) of the migration times and the peak height of the two constituents were in the ranges 0.62--0.79% and 0.25--2.17% (intra-day) and 1.43--2.06 and 4.08--5.72% (inter-day), respectively. The recoveries of the two constituents ranged from 93.2 to 103.0%. The results indicated that baseline separation of the analytes was sometimes hard to obtain in real samples and second-order derivative electropherograms were applicable for the resolution and analysis of overlapping peaks.
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