Simultaneous measurement of contents of liquirtin and glycyrrhizic acid in liquorice based on near infrared spectroscopy

In this paper we proposed to establish calibration models for simultaneous determination of contents of LI and GL in liquorice samples. As the above flowchart shows, PLS regression algorithm was used to relate the reference values of contents of LI and GL determined by HPLC to the samples spectra by NIR. Five popular variable selection methods were investigated. As a result, both calibration models for LI and GI performed well with a clear ranking of GA > PSO > CARS > MCUVE ≅ VIP > Full, thus becoming alternatives for rapid quality evaluation and control of liquorice.52