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 Rb-1, Rb-2, Rc, Rd, Re, Rf and Rg(1) 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 Rb-1, Rd, Re and Rg(1). 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 (R-2) 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.