激光剥蚀-电感耦合等离子体质谱法测定土壤中15种微量元素

Determination of 15 Trace Elements in Soil Samples by LA-ICP-MS

在土壤标准样品中加入内标元素铼,将其压片后直接进样,将激光聚焦在样品表面下100μm,在以下条件下进行激光剥蚀(LA):(1)剥蚀载气氦气流量为600mL·min^(-1);(2)剥蚀光斑直径为110μm;(3)剥蚀速率为50μm·s^(-1)。剥蚀后形成的气溶胶进入电感耦合等离子体质谱仪(ICP-MS),对其中15种微量元素(铍、钒、铬、钴、镍、铜、锌、镓、砷、镉、锡、锑、铊、铅、铋)进行测定。采用标准加入法,通过校准曲线外推得到各目标元素的含量。检出限(3s)为0.01~0.08μg·g^(-1);用此方法分析了2个土壤标准样品(GSS-3和GSS-14),除铍、锑和镉,其他元素所得测定值均在认定值的允许不确定度范围内,且相对误差(RE)均不超过10%;对土壤标准样品(GSS-14)重复测定5次,15种元素测定值的相对标准偏差(n=5)均在10%以内。

Rhenium as internal standard element was added to the soil standard sample,and the sample was injected directly after pressing into tablet.Laser beam was focused at 100μm below the sample surface,and LA was performed as follows:(1)the flow rate of helium as carrier gas was 600 mL·min^(-1);(2) the diameter of ablation light spot was 110μm;(3)the ablation rate was 50μm·s^(-1).The ablation particles obtained were introduced into ICP-MS and 15 trace elements(i.e.Be,V,Cr,Co,Ni,Cu,Zn,Ga,As,Cd,Sn,Sb,Tl,Pb,Bi)were determined.The standard addition method was used to extrapolate to obtain the content of target elements by the calibration curve.Detection limits(3 s)found were in the range of 0.01-0.08μg·g^(-1).Two soil standard samples(GSS-3 and GSS-14)were analyzed by this method.Except for Be,Sb and Cd,the determined values of other elements were all within the allowable uncertainty ranges of the certified values,with relative error(RE)less than10%;the soil standard sample(GSS-14)was analyzed for 5 times,and RSDs(n=5)of the measured values of 15 elements were all within 10%.