熔融制样-X射线荧光光谱法测定蛇纹石中主次组分

针对蛇纹石主次组分同时测定中存在的问题,实验以Li₂B₄O₇-LiBO₂(m:m=33:67)为熔剂,碘化铵和溴化铵做脱模剂,熔融法制备样品,建立了X射线荧光光谱法(XRF)测定蛇纹石中SiO₂、MgO、Fe₂O₃、Al₂O₃、CaO等主次成分的方法。优化后的熔融条件如下:稀释比为10:1,加入4 滴400 g/L NH₄Br溶液和14 滴400 g/L NH₄I溶液做脱模剂,在700 ℃预氧化4 min,再升温到1 050 ℃熔融6 min。选择与蛇纹石矿物相似的滑石、水镁石、非金属矿石物化性能和化学成分分析国家标准物质进行互配,采用基本参数法校正基体效应后,建立校准曲线,解决了蛇纹石标准物质缺失的问题。方法的检出限为80～170 μg/g。对1个东海蛇纹石样品进行精密度考察,测定结果的相对标准偏差(RSD,n=10)均不大于0.70%;采用实验方法对两个蛇纹石样品进行分析,并与行业标准方法HG/T 3575—2006测定结果进行对照,结果相符。

Determination of major and minor components in serpentine by X-ray fluorescence spectrometry with fusion sample preparation

Aiming at the problem in simultaneous determination of major and minor components in serpentine, the sample was prepared by fusion sample preparation method with Li₂B₄O₇-LiBO₂ (m:m=33:67) as flux and ammonium iodide,ammonium bromide as releasing agent. The determination method of major and minor components (including SiO₂, MgO, Fe₂O₃, Al₂O₃ and CaO) in serpentine by X-ray fluorescence spectrometry (XRF) was established. The optimized fusion conditions were as follows: the dilution ratio was 10:1; 4 drops of 400 g/L NH₄Br solution and 14 drops of 400 g/L NH₄I solution were added as the releasing agent; pre-oxidization at 700 ℃ for 4 min; fusion at 1 050 ℃ for 6 min. The national certified reference materials of talcum, brucite and non-metallic ore with similar mineral properties to serpentine were used to prepare the calibration samples. The calibration curve was established using fundamental parameter method to correct the matrix effect. The detection limit was 80-170 μg/g. The precision test was conducted with one serpentine sample from the East China Sea, and the relative standard deviations (RSD, n=10) were not more than 0.70%. The proposed method was applied to the determination of two serpentine samples. The results were consistent with those obtained by industrial standard method (HG/T 3575-2006).