内标校正-电感耦合等离子体发射光谱法测定磷矿石中的磷

Determination of Phosphorus in Phosphate Ores by Inductively Coupled Plasma-Optical Emission Spectrometry Utilizing an Internal Standard Correction Method

采用电感耦合等离子体发射光谱法(ICP-OES)可以同时测定磷矿石中的主、次量元素,但在实际测量过程中,仪器的漂移以及基体效应引起的分析误差不容忽视。本文以碲为内标,对高含量磷的测定进行校正,可以有效降低由仪器漂移以及基体效应引起的分析误差,12次平行测定磷的相对标准偏差(RSD)为0.5%,与未经校正的RSD值(4.1%)相比,显著提高了分析精度,极大地降低了仪器波动对测定结果的影响,因此获得了更低的方法检出限(0.0044%)。实验还对比了王水溶样与盐酸-硝酸-氢氟酸-高氯酸(四酸)溶样两种样品前处理方法对磷矿石分析的影响,结果表明:以王水对磷矿石标准物质进行快速溶解,磷、钙、铁、镁、锰等元素的测定结果与标准值间的相对误差范围为-6.7%~1.6%,满足日常测定要求;而钾、钠、铝是否能够完全溶出与样品的矿物组成及氟含量存在联系,若需要分析钾、钠、铝等元素,如果样品中的硅酸盐矿物组成不多,氟含量较高时可以考虑采用王水溶解;四酸可以完全溶解样品,适合于磷、钙、铁、镁、铝、钾、钠、锰、锶等元素的同时测定。

Inductively Coupled Plasma-Optical Emission Spectrometry has been widely used to determine major and minor components in phosphate ores. However , the analysis error caused by instrument drift and matrix effect cannot ignored. In this study, tellurium was used as the internal standard element in order to reduce the instrument drift and matrix effect during determination of high phosphorous content. The relative standard deviation for 12 repeated analyses is 0. 5% , which is better than that without calibration （4.1 % ）. The lower detection limit （0.0044%） was achieved by internal standard correction for phosphorus determination. Two kinds of acid digestion methods, aqua regia and a mixture of HCl,HNO3, HF and HClO4, for phosphate ore were compared in this work. The results indicate that rapid digestion by aqua regia was suitable for some elements such as phosphorus, calcium, iron, magnesium, manganese analysis, with relative error ranging from -6.7% to 1.6 % . The complete digestion of K, Na, Al is related to mineral components and F content of samples. If K, Na, and A1 are needed to analyze and there are only a few silicate minerals but a lot of F-bearing components, aqua regia can be used. A mixture of HCl, HNO3 , HF and HClO4 can completely digest samples and is suitable for determination of P, Ca, Fe, Mg, Al, K, Na,Mn and Sr.