高压粉末制样波长色散 X射线荧光光谱法测定生物样品中23种元素

摘要

In the determination of biological samples by X-ray Fluorescence Spectrometry (XRF),sample powder pellets pressed by traditional sample preparation technique at 220-440 MPa are not compact and smooth,so the sample room of XRF instrument becomes contaminated by dropped sample powder,which can then influence long-term stability.Biological sample powder can be pressed into smooth and compact pellets using high pressure of 1 760 MPa,therefore the sample preparation reproducibility is improved to 0.1% -2.6% (RSD,n=5 ). A method for direct determination of 23 major and minor elements (Al,Ca,Cl,K,Mg,Na,P,S,Si,Ba,Br, Co,Cr,Cu,Fe,Mn,Ni,Pb,Rb,Sr,Ti,V and Zn)in biological samples by Wavelength Dispersion X-ray Fluorescence Spectrometry was established on this sample preparation basis.The matrix effects can be corrected by using Rh-Kα(from the X-ray tube target)Compton-scattered radiation and by using the background as the internal standard.The precision of the method is 0.4%-1 1 .3%(RSD)for most elements and the detection limits is 0.08-1 40.96 μg/g.The feasibility of the proposed method was tested by analyzing several national biological standard materials;the results obtained were consistent with the certified values.%应用X射线荧光光谱法（XRF）分析生物样品时，采用传统低压粉末制样方法（压强220～440 MPa）难以将样品压制成符合测定需要的样片，样片表面粗糙，粉末容易脱落，污染XRF仪器样品室，影响仪器的长期稳定性。本文采用高压粉末制样方法在1760 MPa下压制则完全克服了低压制样的弊端，制备的样片表面光滑、致密，大幅改善了制样重现性，5次制样重现性为0．1％～2．6％，且降低了仪器的维护成本。在此基础上，建立了波长色散X射线荧光光谱法直接测定生物样品中23种主次量元素（Al、Ca、Cl、K、Mg、Na、P、S、Si、Ba、Br、Co、Cr、Cu、Fe、Mn、Ni、Pb、Rb、Sr、Ti、V、Zn）的分析方法，采用经验系数法、散射线内标法和峰背景作内标校正基体效应，大部分元素的方法精密度提高至0．4％～11．3％，检出限为0．08～140．96μg／g。经国家一级生物标准物质验证，表明方法准确可靠，能满足日常分析要求。