Determination of Metallic Elements in Environmental Samples by Matrix-Assisted Microwave Induced Plasma Surface Sampling Atomic Emission Spectrometry

Abstract

A novel method for the determination of metallic elements in environmental samples was developed based on matrix-assisted plasma surface sampling atomic emission spectrometry. A piece of filter paper was used as sample substrate. By direct interaction of the plasma tail plume with the filter paper surface, the filter paper absorbed energy from the plasma source and released combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. Surface sampling was performed in cases of both liquid and solid state analytes. Therefore, no flow injection system was required and the sample pretreatment process was simplified. The proposed method provided several advantages, including fast analysis speed (about 240 samples per hour), little sample consumption (μL or μg level), and simple instrument design and system operation. These advantages made it attractive as a potential miniaturized atomic emission spectrometry (AES) system for in situ and high-throughput elemental analysis. Quantitative analysis of metal ions was achieved in this study for elements Ag, Au, Ba, Cd, Cr, Cu, Eu, La, Mn, Ni, Pb, Sr and Y. Under the optimal conditions, the LOD values of the 13 elements ranged from 1.0 to 88 ng mL−1. Repeatability, expressed as relative standard deviation (RSD) from 10 replicates, ranged from 2.3% to 6.8%. To validate the proposed method, the system was employed to determine metallic elements in standard reference materials of environmental samples. The content of each element detected by this system was well in agreement with the certified values.