Application of quantitative 1H-NMR method to determination of paeoniflorin in Paeoniae radix

A quantitative (1)H-NMR method (qHNMR) was used to measure paeoniflorin content in Paeoniae radix (dried root of Paeonia lactiflora), of which paeoniflorin is a major component. The purity of paeoniflorin was calculated from the ratio of the intensity of the H-9 signal at δ 5.78 ppm of paeoniflorin to that of a hexamethyldisilane (HMD) signal at 0 ppm. The concentration of HMD was corrected with SI traceability by using bisphenol A of certified reference material (CRM) grade. The paeoniflorin content in 2 separate samples of Paeoniae radix was determined by qHNMR and was found to be 2.15 and 2.45%. We demonstrated that this method is useful for quantitative analysis of crude drugs.