ABSTRACT
Glycyrrhiza is traditional Chinese medicine, whose active compounds have great potential in treating COVID-19. Detecting harmful trace elements of glycyrrhiza has become essential. However, it is not easy to detect trace elements due to the complex matrix of nonstandard glycyrrhiza. Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) can be used in quantitive of nonstandard, but its stability and accuracy are low. To detect trace elements of glycyrrhiza quickly and accurately, this work introduced the standard addition method and internal standard method into LIBS, namely SAIS-LIBS. SAIS-LIBS was applied to determine trace copper and manganese in glycyrrhiza. The results showed that SAIS-LIBS had higher efficiency (<0.3 h), and could be up to 3-25 times more accuracy and stability than CF-LIBS. Furthermore, SAIS-LIBS results and inductively coupled plasma-optical emission spectroscopy (ICP-OES) were very similar (p-values > 0.05). This research provided a foundation for the rapid and accurate detection of harmful trace elements in glycyrrhiza.