Determination of Manganese in Soil by Inductively Coupled Plasma Atomic Emission Spectrometry with Microwave Digestion

A method for the determination of manganese in soil by inductively coupled plasma atomic emission spectrometry (ICP-AES) with microwave digestion was established. Soil sample of 0.25 g in a microwave digestion tank was digested with nitric acid of 4.0 mL, hydrofluoric acid of 5.0 mL, 30% (w, the same below) hydrogen peroxide solution of 1.0 mL under the microwave program, and perchloric acid of 1.0 mL was added to remove acid. 50% (φ) nitric acid solution of 5.0 mL and 4-6 drops of 30% hydrogen peroxide solution were used to dissolve the residue. The solution was diluted and made its volume up to 50 mL by water and determined by ICP-AES. As shown by the results, linear relationship between mass concentration of manganese and its signal intensity was kept within 10.0 mg·L^-1, with detection limit (3s) of 0.100 mg·kg^-1. RSDs (n=6) of the determined values of soil standard substances were ranged from 1.7% to 2.4%, and the determined values were consistent with the certified values, with the relative errors in the range of -0.33%-0.13%.