Point discharge microplasma for the determination of mercury in Traditional Chinese Medicines by chemical vapor generation atomic emission spectrometry

Abstract A miniaturized analysis system based on a low power point discharge (PD) microplasma is described for mercury detection in Traditional Chinese Medicines (TCM) by chemical vapor generation atomic emission spectrometry (CVG-AES). The PD microplasma utilized a stainless-steel hollow needle as one of the electrodes, which also acts as the channel for the plasma gas and Hg vapor to enter the discharge region. This design allows the Hg vapor all transported and confined into the microplasma by internal diffusion, which helps to improve the sample introduction efficiency and excitation efficiency. Because of the efficient matrix separation by CVG, high selectivity and stability can be realized with this system. Under the optimized conditions, the limit of detection (LOD) was found to be 0.15 ng mL−1. The RSD (n = 7) was 2.7% for 5 ng mL−1 of Hg2+. The proposed technique has been applied to the investigation of Hg content in TCM drugs with satisfactory analytical results. The method provides several advantages including simple, high sensitivity, compactness and cost-effectiveness for mercury assay in TCM.