超细固体悬浮液进样-电感耦合等离子体质谱法测定土壤中的微量元素

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

固体进样技术应用于土壤样品测量领域,一直受制于样品粒径的限制,无法应用在配有气动雾化器的分析仪器上。本文系统研究了土壤样品超细粉碎技术,在乙醇介质下,数分钟内将其粉碎至微米级,经此制成的固体悬浮液直接进行电感耦合等离子体质谱法(ICP-MS)测定,可以避免气动雾化器的堵塞。标准物质测定表明,样品粒径为6.8μm时,固体悬浮液进样仍然存在干扰,通过在固体悬浮液中加入少量氢氟酸和硝酸,对固体悬浮液进行改性,减小了固体悬浮液中固体颗粒粒径,从而减少了样品粒径的影响,可用ICP-MS测定土壤中锂铍钒铬镍铜锌铷锶镉铯钡铅等13个微量元素。经国家一级标准物质验证,本方法的最大相对误差在10.5%左右,多数元素的相对误差小于5%,相对标准偏差(RSD)小于5.4%(镉元素除外),满足了DZ/G 0130—2006质量控制要求。

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’.