Determination of 6 Metal Elements in Soil by Inductively Coupled Plasma Atomic Emission Spectrometry with Sodium Matrix Matching Method

At specific wavelengths, the effects of different mass concentrations of soil matrix and easily ionizable elements on determination of 6 metal elements (zinc, manganese, copper, nickel, cobalt, and vanadium) by inductively coupled plasma atomic emission spectrometry (ICP-AES) were compared. As shown by the results, a certain correlation between soil matrix interference and easily ionizable element interference. Negative interference was observed for all 6 metal elements, with significantly greater interference on copper, nickel and cobalt compared to zinc and vanadium. By selecting the sodium chloride solution with sodium mass concentration of 1 000 mg·L⁻¹ as the matrix for drawing calibration curves, the interference from the soil matrix with a sample mass of 0.3 g could be calibrated, thereby achieving accurate determination results. Using the sodium matrix matching method, linear relationships between the corresponding emission intensities and mass concentrations of 6 metal elements were found in definite ranges, with detection limits (3.14s) in the range of 0.1-0.5 mg·kg⁻¹. Accuracy tests were conducted on 6 soil composition analysis standard materials, and the relative errors of the determined values ranged from -3.8% to 4.0%. Precision test was conducted on the soil composition analysis standard material GSS20, and RSDs (n=6) of the determined values ranged from 1.8% to 4.0%. This method was applied to analysis of 3 different environmental soil samples, and the obtained results were consistent with those of wavelength dispersive X-ray fluorescence spectrometry.