高压粉末制样-X射线荧光光谱法测定地质样品中铌锆和主量元素

Determination of Niobium, Zirconium and Major Elements in Geological Samples by X-ray Fluorescence Spectrometry with High-Pressure Powder Pelletization

  • 摘要: 在X射线荧光光谱(XRF)分析中,粉末压片制样是一种绿色、无污染的制样技术,但采用常规粉末制样(400kN)存在较大的粒度效应和矿物效应,往往造成测试结果误差较大,且地质样品种类繁多,当样品本身黏结性较差时常难以压制成型,会出现表面粗糙、脱落,通过增加制样压力可减少粉末颗粒间的空隙,从而降低矿物效应。本文使用高压压片(800kN)制样能将各种类型的地质样品压制成型,样片表面平滑、致密且不掉粉末,测量时不会对XRF仪器分析室造成污染。实验使用硅酸盐岩石、沉积物及土壤国家标准物质建立校准曲线,采用经验法和散射线内标法校正基体效应和元素谱线重叠干扰,对样片表面形态、校准曲线斜率及重现性等方面进行了对比研究。结果表明使用高压制样建立的校准曲线优于常规压力制样,各组分检出限明显降低,精密度(RSD,n=4)均有较大提高,如GBW07453中Nb和Zr的相对标准偏差(RSD,n=4)分别从3.80%和1.55%降到1.66%和0.77%。实际样品的测定结果与熔融法基本相符,并且Nb和Zr的测定值与化学值相吻合。采用高压制样技术,实现了XRF法同时测定地质样品中铌、锆及主量元素。

     

    Abstract: Powder tablet is a kind of green and pollution-free sample preparation technology, but the conventional powder sample preparation (400kN) has large particle size effect and mineral effect, which often results in large error, and some samples are difficult to press into shape, but increase the pressure of sample preparation can reduce the voids between powder particles, thereby reducing the mineral effect. In this paper, high pressure sample preparation (800kN) technology can be used to press various types of silicate samples into shape, the surface of the sample is smooth and compact. The experiment used national first-class standard materials of silicate rocks, sediments, and soils to establish calibration curves. It corrected the matrix and the overlap of element spectral lines using empirical methods and internal standard methods. By comparing the surface morphology of the samples, the slope of the calibration curve and reproducibility, the study found that the calibration curve established using high-pressure sample preparation was better than that using conventional pressure sample preparation. The detection limits were reduced, and the precision of most components was below 1.0%. The relative standard deviation (RSD) of GBW07453 (RSD, n=4) for niobium and zirconium were 1.66% and 0.77%, respectively, which were greatly improved compared to conventional pressure sample preparation (RSD of niobium and zirconium were 3.80% and 1.55%, respectively). The analysis of actual showed that the measured values of niobium and zirconium were consistent with the chemical values. This method used high-pressure sample preparation technology to achieve the determination of niobium, zirconium, and major elements in geological samples by X-ray fluorescence spectrometry, and the analysis results met the requirements of analysis.

     

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