Rapid and sensitive analysis of trace elements in medicinal Codonopsis pilosula using laser-induced breakdown spectroscopy assisted by a micro-array copper sieve

Abstract

Medicinal herbs are widely used in the treatment of various diseases owing to their rich composition of bioactive organic compounds as well as essential elements beneficial to human health. In this work, a cost-effective and convenient method termed micro-array copper sieve (MACS) enhanced laser-induced breakdown spectroscopy (LIBS) was proposed to improve the detection sensitivity of elements in powder samples. In order to overcome the problem of diversity of the sample shape, size and density, the original samples of Codonopsis pilosula were pulverized to powder. A MACS was placed on the surface of the powder samples and then they were pressed into cylindrical tablets for spectral analysis. The surface of the Codonopsis pilosula tablet was embedded with a MACS after pressing. Plasma with higher temperature and higher electron density could be generated compared with samples without a MACS. To evaluate the analytical sensitivity improvement factor of this method, iron, chromium, manganese, and aluminum in samples were analyzed, and 2.2–6.5 fold improvements in the analytical sensitivity were achieved. It was demonstrated that the MACS was able to improve the analytical sensitivity of LIBS while analyzing powder samples and could be potentially applied to elemental analysis of herbs.