Determination of marker constituents in radix Glycyrrhizae and radix Notoginseng by near infrared spectroscopy

High-performance liquid chromatographic (HPLC) methods were developed for the determination of glycyrrhizin in radix Glycyrrhizae and ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf and Rg, in radix Notoginseng. These methods were used as reference methods for near-infrared (NIR) spectroscopy. Spectroscopic calibrations were developed for the determination of glycyrrhizin, the total content of ginsenosides and the individual major ginsenosides Rb1, Rd, Re and Rg1. Standard errors of cross validation (SECV) were 1.22 mg g(-1) for glycyrrhizin (concentration range 21.3-34.1 mg g(-1)) and 0.99 mg g(-1) for the sum of ginsenosides (concentration range 55.3-71.1 mg g(-1)). The corresponding coefficients of determination (R2) were 0.94 and 0.98, respectively. The SECVs were generally less than a factor of 2.5 of the repeatability standard deviation of the HPLC methods.