Separation and determination of three water-soluble compounds in Salvia miltiorrhiza Bunge and two related traditional medicinal preparations by flow injection-capillary electrophoresis

A sensitive and reproducible method was developed for the separation and determination of three water-soluble components—protocatechuic aldehyde (PAH), β-(3,4-dihydroxyphenyl) lactic acid (DSS) and protocatechuic acid (PA) in medicine plant Salvia miltiorrhiza Bunge and two related traditional medicinal preparations using flow injection-capillary electrophoresis system. This analysis was carried out by using an unmodified fused-silica capillary (28.4 cm × 75 μm i.d. × 375 μm o.d., 25 cm effective separation length) and direct ultraviolet detection at 214 nm, 7.0 kV applied voltage. With boric acid (200 mM) adjusted to pH 7.8 as a background electrolyte. The separation was achieved in 9 min. The sample throughput rate could reach up to 15 h−1. Calibration curves showed good linearity with correlation coefficients (r) more than 0.9986. The repeatability (defined as R.S.D.) were 0.20%, 0.46%, 0.47% with migration time evaluation and 0.62%, 3.66%, 1.50% with peak area evaluation for PAH, DSS and PA, respectively. The limits of detection (S/N = 3) were 0.36 μg/mL, 0.84 μg/mL, and 0.73 μg/mL for PAH, DSS, and PA, respectively. The mean recoveries of PAH, DSS and PA were 103.2%, 98.1% and 100.5%, respectively. This method has been applied successfully to monitor these three components in Salvia miltiorrhiza Bunge and its two traditional medicinal preparations.