Fast determination of betaine in Lycii Fructus by ultra-performance convergence chromatography-tandem mass spectrometry

Abstract

Over the past 2500 years, Lycii Fructus has been widely used as a functional food and tonic in Chinese herbal medicine. It can nourish the liver and kidneys, moisten the lungs, and improve eyesight. In this study, a new rapid and sensitive method has been developed for the quantitative determination of betaine (index compound) in Lycii Fructus by using ultra-performance convergence chromatography-tandem mass spectrometry (UPC2-MS). The separation of betaine was successfully achieved on an ACQUITY UPC2 BEH 2-EP column (150 mm×2.1 mm, 1.7 μm), with isocratic elution by a CO2-methanol (80:20, v/v) solvent at a flow rate of 0.7 mL/min. The conditions used in the separation process were as follows:modifier, 0.1% (v/v) formic acid in methanol; column temperature, 40℃; backpressure, 1.31×107 Pa; injection volume, 1 μL; and retention time, 3 min. The MS system was equipped with an electrospray ionization (ESI) ion source and operated in the selected ion recording (SIR) and positive ion mode. Under the abovementioned conditions, the calibration curve was obtained. The linear range of detection was 0.5-50.0 μg/mL, with a correlation coefficient of 0.9992, and the limit of detection (LOD) was found to be 0.013 μg/mL. The validity of the method was tested by analyses of precision, repeatability, stability, and accuracy (average recovery:96.3%). Finally, the developed method was applied to analyze 11 batches of samples. The results indicated that this method was suitable for evaluating the quality of Lycii Fructus.