Determination of 12 Heavy Metal Elements in Soil by Inductively Coupled Plasma Mass Spectrometry with Automatic Graphite Digestion

An aliquot about 0.100 0 g of treated soil sample was taken, and wetted with a small amount of water. Nitric acid (3 mL), hydrofluoric acid (3 mL) and perchloric acid (1 mL) were used as acid system, and the sample were digested at 150 ℃ for 2.0 h by a automatic graphite furnace digester. After the digestion was completed, the acid was removed, and the digestion solution and water rinsing solution were transferred into a 50 mL-volumetric bottle, and then diluted with water to volume. After mixing well, the above solution was filtered through a 0.45 μm filter membrane, and the filtrate was determined according to the working conditions of the inductively coupled plasma mass spectrometer. It was shown that linear relationships between the values of mass concentrations of 12 heavy metal elements including vanadium, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, cadmium, lead, molybdenum and antimony and response intensity ratios of their to internal standards were within 200 μg·L^-1, with detection limits (3s) in the range of 0.008-0.250 μg·g^-1. Tests for accuracy and precision on the soil standard samples GSS-13, GSS-19 and GSS-23 were carried out, and the determined values were within the uncertainty ranges of the confirmed values, and RSDs (n=6) of the determined values were less than 4.0%. The method was used to analyze 5 actual soil samples, and the determined values of 12 heavy metal elements did not exceed the national secondary standard of soil environmental quality.