Determination of Trace Elements in Soil by Inductively Coupled Plasma-Mass Spectrometry with Ultrafine Slurry Sampling

BACKGROUND Solid sampling technology applied in soil sample measurement has the limitation of sample size, and cannot be applied to the mainstream element analysis instrument. OBJECTIVES To determine the trace elements by smashing soil samples to micron scale by high-speed grinding technology and under the action of a dispersant. METHODS The ultra-fine grinding technology of soil samples was systematically studied. The sample was crushed to micron level in a few minutes in an ethanol medium. The prepared solid suspension was directly measured by ICP-MS, avoiding blockage of pneumatic atomizers. RESULTS The determination of the reference materials shows that the solid suspension still has interference when the particle size is 6.8μm. By adding a small amount of hydrofluoric acid and nitric acid to modify the solid suspension, the solid particle size was reduced and thereby the impact of the sample size was reduced. The 13 trace elements of lithium, beryllium, vanadium, chromium, nickel, copper, zinc, rubidium, strontium, cadmium, cesium, barium and lead were successfully determined by ICP-MS. Accuracy experiment showed that the maximum relative error is 10.5%±3% and most of the elements have a relative error less than 5%. The precision experiment showed that most elements have a relative standard deviation (RSD) of less than 5.4%. CONCLUSIONS The determination results meet the requirements of DZ/G 0130-2006 'Test of Geology and Mineral Resources Quality Management Standards'.