Dual-spectrum online monitoring of puerarin and total flavonoids contents during the extraction process of Pueraria lobata

In the extraction process of traditional Chinese medicine (TCM), the rapid detection of the active components of TCM plays a vital role. We pioneered the choice of dual-spectrum technology based on near-infrared (NIR) and ultraviolet-visible (UV-Vis) spectra and applied it to the quantitative monitoring of online extraction of puerarin and total flavonoids from Pueraria lobata. An online monitoring system was constructed to fulfill the dual-spectrum online monitoring. The extraction solution flows from a flask into a pipeline under the control of a peristaltic pump, removing the solid residues contained in the solution with filters. When the extraction solution flows into the cuvette, it will be measured with NIR and UV-Vis portable spectrometers. After finishing the spectra collection, the peristaltic pump will reverse to push the extraction solution back to the flask. The partial least squares (PLS) models were established to quantitatively analyze puerarin and total flavonoids by NIR, UV-Vis, and dual-spectrum data. As for NIR, UV-Vis and dual-spectrum, the RMSEP (mg/mL) of the puerarin models were 0.0803, 0.0500, and 0.0351, and those of the total flavonoids models were 0.4373, 0.2402, and 0.1795, respectively. The results show that the dual-spectrum online monitoring system is simple, stable and fast (a few seconds) in operation, and accurate in prediction. Compared with individual NIR or UV-Vis spectra, the dual-spectra contains more comprehensive information, and the prediction ability is stronger. This method is expected to become a promising tool for the quantitative analysis of other traditional Chinese medicines.