Determination of 16 Metal Elements in Soil by Inductively Coupled Plasma Mass Spectrometry with Triacid Microwave Digestion and Nitric Acid Extraction

A method for simultaneous determination of 16 metal elements including Be, V, Cr, Mn, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl, Pb, Th and U in soil by inductively coupled plasma mass spectrometry (ICP-MS) with microwave digestion was proposed. The soil sample (0.100 0 g) was digested by microwave in 5 mL of nitric acid, 1 mL of hydrochloric acid and 1 mL of hydrofluoric acid. After digestion, the mixture was cooled to room temperature, and the acid was driven at 160℃ until the liquid disappeared completely. 2 mL of nitric acid was added into the residue, and its volume was made up to 50 mL with deionized water. After shaking well, the solution was passed through 0.45 μm filter member and determined by ICP-MS, and the internal standard element was introduced online. As shown by the results, linear relationships between the mass spectral intensity and the mass concentration of 16 metal elements were found in definite ranges, with detection limits of 0.008-0.41 mg·kg^-1. This method was applied to analysis of soil reference materials with different contents, and the determined results were basically consistent with the certified values, with RSDs (n=6) of the determined values less than 5.0%.