火焰原子吸收光谱法测定氢氧化铈中氧化钾

氢氧化铈具有无毒的特性,作为铈基功能材料在汽车尾气净化催化剂以及高端电子研磨新材料等领域得到广泛应用,而快速准确地测定氢氧化铈中氧化钾含量对产品的质量控制具有重要意义。氢氧化铈产品中氧化钾质量分数要求不大于0.000 3%,但氧化铈的基体效应干扰氧化钾的测定。实验采用盐酸溶解样品,以草酸分离铈基体,滤液在3%(V/V)的盐酸介质中,以标准加入法绘制工作曲线,建立了空气-乙炔火焰原子吸收光谱法测定氢氧化铈中氧化钾含量的方法。考察了铈基体对钾测定的影响,结果表明,基体铈干扰钾的测定,实验选择在草酸分离大量铈后,采用标准加入法消除草酸基体效应对钾测定的影响。方法检出限为0.50 μg/g,定量限为2.0 μg/g。干扰试验表明,以标准加入法的校正模式进行氢氧化铈中氧化钾含量的测定,样品中共存元素铝、钙、钠、铁、锰、锌、镁和铅对钾测定的干扰可忽略。方法应用于氢氧化铈实际样品中氧化钾的测定,结果的相对标准偏差(RSD, n=11)小于20%。回收率为95%～103%。

Determination of potassium oxide in cerium hydroxide by flame atomic absorption spectrometry

Cerium hydroxide is non-toxic and has been widely used as a cerium-based functional material in the fields of automobile exhaust purification catalyst and high-end electronic grinding new materials. The rapid and accurate determination of potassium oxide content in cerium hydroxide is of great significance to the quality control of products. The mass fraction of potassium oxide in cerium hydroxide products is required to be lower than 0.000 3%, but the matrix effect of cerium oxide has interference with the determination of potassium oxide. The sample was dissolved with hydrochloric acid followed by separation of cerium matrix with oxalic acid. The filtrate was analyzed in 3% (V/V) hydrochloric acid medium. The calibration curve was prepared by standard addition method. The determination method of potassium oxide content in cerium hydroxide by air-acetylene flame atomic absorption spectrometry (FAAS) was established. The effect of cerium matrix on the determination of potassium was investigated. The results showed that the cerium matrix had interference with the determination. In experiments, a large amount of cerium was separated with oxalic acid, and the influence of oxalic acid matrix effect on the determination of potassium was eliminated by standard addition method. The limit of detection was 0.50 μg/g. The limit of quantification was 2.0 μg/g. The interference tests indicated that the interference of coexisting elements in sample including aluminum, calcium, sodium, iron, manganese, zinc, magnesium and lead could be ignored when the content of potassium oxide in cerium hydroxide was determined using correction mode of standard addition method. The proposed method was applied for determination of potassium oxide in actual cerium hydroxide samples. The relative standard deviation (RSD, n=11) of determination results was less than 20%, and the recoveries were between 95% and 103%.