Rapid and simultaneous determination of salvianolic acid A and salvianolic acid B by complex chromatography and study on related mechanism of coordination

Salvianolic acid A (Sal A) and salvianolic acid B (Sal B) are water-soluble phenolic acids in Danshen extract and they have high medicinal value. A rapid and novel complex high-performance liquid chromatography (HPLC) method has been developed and validated for the simultaneous determination of Sal A and Sal B within 10 min. The determination of Sal A and Sal B was carried out on a Waters Symmetry Shield RP18 column (5 μm, 3.9 mm × 150 mm), using methanol-deionized water (55:45, v/v, with 5 mmol L−1 CaCl2 and 1% acetic acid) as the mobile phase at the flow rate of 0.8 mL min−1 within 10 min. The wavelength was set at 280 nm. It changed the peak sequence of Sal A and Sal B and improved their effect of determination by adding CaCl2 in the mobile phase because Sal A and Sal B coordinated with Ca2+. The mechanism of coordination between Sal A, Sal B and Ca2+ has been studied by way of Fourier transform infrared spectroscopy (FTIR), electrospray ionization mass spectrometry (ESI-MS) and computer model. The possible structures of the complex and complex ratio are provided in this article. The experiments have facilitated the study of Sal A–Ca2+ complex, Sal B–Ca2+ complex and provide a theoretical basis for industrialized extraction of Sal A and Sal B in the future.