Rapid qualitative and quantitative analyses of Asian ginseng in adulterated American ginseng preparations by UPLC/Q-TOF-MS

Abstract

A new method using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was developed for the rapid qualitative and quantitative analyses of Asian ginseng ( Panax ginseng C.A.Meyer) in adulterated American ginseng ( Panax quinquefolium L.) preparations within 2 min. The method was based on the baseline chromatographic separation of isomeric compounds of ginsenoside Rf and 24(R)-pseudoginsenoside F 11, two potential chemical markers present in Panax ginseng C.A.Meyer and P. quinquefolium L. methanolic extracts. The chromatographic separation was achieved by UPLC, which used a column with 1.7 μm particle packing which enabled the higher peak capacity, greater resolution, increased sensitivity and higher speed of analysis. Ginsenoside Rf and 24(R)-pseudoginsenoside F 11 were separated on baseline with retention times of 1.5 and 1.7 min, respectively. Ginsenoside Rf and 24(R)-pseudoginsenoside F 11 were identified and conformed unambiguously by accurate mass measurement and their different fragmentation pathways were performed on Q-TOF-MS. Quantitative analysis was carried out under selective ion monitoring (SIM) mode. The limit of detection (LOD) of this UPLC/Q-TOF-MS analysis for ginsenoside Rf and 24(R)-pseudoginsenoside F 11 was 0.05 and 0.08 ng, respectively. Ginsenoside Rf was linear over the range of 0.164–16.4 ng with a correlation coefficient ( R 2) of 0.9997, while 24(R)-pseudoginsenoside F 11 was linear from 0.243 to 24.3 ng with an R 2 of 0.9989. Furthermore, inter-day and intra-day precisions were obtained below 4.0% and the analytical method was fully validated. 12 batches of self-prepared adulterated samples, 11 batches of Asian ginseng, 16 batches of American ginseng and 13 batches of commercial American ginseng preparations were tested. The method developed is rapid, accurate, reliable and highly sensitive for qualitative and quantitative analyses of Asian ginseng and American ginseng.