The chemical transformations for Radix Astragali via different alkaline wash conditions by quantitative and qualitative analyses

Radix Astragali is a famous Chinese traditional and folk medicine with a wide range of medicinal values in clinic. In this study, an analytical efficient strategy based on UHPLC-QQQ-MS/MS and UHPLC-LTQ-Orbitrap-MS/MS was established to explore and reveal the chemical transformations for Radix Astragali under different alkaline wash conditions for analytical sample preparation. Firstly, a rapid and sensitive UHPLC-QQQ-MS/MS method for the quantification of 14 main constituents in Radix Astragali has been developed and validated. Secondly, according to the standard substance comparison, accurate mass measurements, mass fragmentation behaviors and related literatures, a total of 102 components have been screened and identified using UHPLC-LTQ-Orbitrap method. Among them, 47 compounds are saponins, and the other 55 are flavonoids. Consequently, there were two chemical transformations including hydrolysis and degradation observed when Radix Astragali was treated with alkali. Besides, hydrolysis of glycosides and acetyl played a considerably important role in the process of sample preparation. It has been proved that 10 % ammonia could relatively guarantee the high content of astragaloside IV and avoid the over-degradation of most chemical ingredients in Radix Astragali. In conclusion, this work would provide a scientific and practical method for quality control of Radix Astragali as well as its compound preparations.