Analysis of metallic elements dissolution in the Astragalus at different decocting time by using LIBS technique

Astragalus is an important traditional Chinese herb that has therapeutic potential in the treatment of diseases. In this study, the dissolution of metallic elements during the material decoction process was investigated using laser-induced breakdown spectroscopy (LIBS). The Ca, Mg, Al, and Fe in the drug residues, liquid, and vapor were selected for the study of the transfer of elements after different decocting times. It was found that the intensities of the spectral lines for these elements in the drug liquid increased with increasing decocting times. The contrast trend was observed in the residues and only calcium was detected in the vapor. Furthermore, the relative mass concentrations of Ca, Mg, Al, and Fe in the liquid were quantitatively determined by a combination of the standard addition method and calibration-free-LIBS method by adding the standard concentration solution of Cu and Cd elements into the drug liquids, it can be found that the maximum error between Cd concentration calculated by internal CF-LIBS and the standard is within 10%. This provides a new method of achieving the on-line monitoring and analysis of metallic elements in the production of traditional Chinese medicines.