Simultaneous determination of bromhexine HCl and baicalin in Chinese compound medicine by a reversed-phase ion-pair HPLC

In this article, a reversed-phase ion-pair high-performance liquid chromatography (HPLC) method was established for simultaneous separation and quantitative analysis of bromhexine HCl (BHH) and baicalin in Chinese Ke-Chuan-Ling compound capsule. The influence of the mobile phase composition on the retention of the analytes was investigated. The optimal determination conditions consisted of acetonitrile/water/phosphoric acid/triethylamine (22/78/0.1/0.1, v/v/v/v) mobile phase with the addition of tetra-n-butylammonium bromide (TBA) (0.7 mmol L^-1, terminal concentration) as pairing ion, and a detection wavelength at 225 nm. In this case, baicalin and bromhexine HCl were eluted at 21 min and 27 min respectively and were separated successfully from other ingredients. Excellent linear relationship between the peak area and concentration was obtained in the range of 0.2-15.0 μg mL^-1 for bromhexine HCl and 0.1-12.0 μg mL^-1 for baicalin. The limit of detection of BHH was 0.1 μg mL^-1 and it was 0.05 μg mL^-1 for baicalin. The average recoveries of bromhexine HCl and baicalin were 97.7% and 99.1%, respectively. From the results it can be concluded that this method is simple, versatile, and reliable for the quality control of Chinese traditional medicines containing baicalin and/or bromhexine HCl.