Rapid and intelligent discrimination of Notopterygium incisum and Notopterygium franchetii by infrared spectroscopic fingerprints and electronic olfactory fingerprints.

Abstract

This preliminary research evaluated mid-infrared (MIR) spectroscopy, near-infrared (NIR) spectroscopy and electronic nose (E-nose) for the rapid identification of Notopterygium incisum and Notopterygium franchetii, which were both approved sources of Notopterygii Rhizoma et Radix (Chinese Pharmacopoeia, 2015) but possessed different chemical compositions and pharmacological activities. At the level of single variables, MIR showed quite a few discriminating peaks in the regions of 3000-2800cm-1 (the stretching bands of CH), 1770-1670cm-1 (the stretching bands of CO), and 1400-1200cm-1 (the bending bands of CH and the stretching bands of CO). Meanwhile, NIR only showed an intuitive discriminating peak near 4736cm-1 (the combination band of OH and CO stretching modes). E-nose response signals of N. incisum and N. franchetii were significant different (p<0.05) on four sensors, i.e., LY2/LG, LY2/GH, LY2/gCT and LY2/gCTI. Using the infrared spectra or E-nose sensor responses as fingerprints, support vector machine (SVM) models can provide good recognition accuracy (100% for MIR and NIR models, 92.9% for E-nose model). This research indicated the feasibility of MIR, NIR and E-nose for the accurate, rapid, cheap and green identification of N. incisum and N. franchetii, which was desirable to assure the authenticity, efficacy and safety of related herb materials and products.