[Determination of seven indicative ingredients in oral liquids of Chinese medicine by liquid chromatography-electrospray ionization-ion mobility spectrometry].

A two-dimensional separation and analysis method, based on liquid chromatography-electrospray ionization-ion mobility spectrometry (LC-ESI-IMS), is developed for the determination of seven indicative ingredients (danshensu, glycyrrhizic acid, gastrodin, chlorogenic acid, puerarin, baicalin, and rutin) in oral liquids of Chinese medicine. The sample was first separated on an ACQUITY UPLC BEH C column (50 mm×1 mm, 1.7 μm). The post-column effluent was directed to an adjustable flow splitter with a split ratio of 50:1. The low-flow and high-flow outlets were connected to an ion mobility spectrometer and a triple quadrupole mass spectrometer, respectively. The experimental conditions for LC, spray voltage, drift tube temperature, gas pre-heating temperature, and drift gas velocity were systematically optimized. The limits of detection (LODs) and quantitation (LOQs) for the seven analytes were 2-10 μg/mL and 5-25 μg/mL, respectively. The proposed method was applied for the analysis of real oral liquids of Chinese medicine samples. By coupling LC and IMS, two-dimensional separation could be achieved based on hydrophobicity difference and ionic mobility disparity, thus providing more comprehensive measurement information than LC or IMS used alone.