电感耦合等离子体发射光谱法测定铬矿石中的二氧化硅

摘要

Chrome ore samples were digested with Na2O2. After the whole process of high temperature melting extracted with hot water-hydrochloric acid, the SiO2 in sample solutions was directly determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) , adding Au as an internal standard element. The matrix interference is discussed in this paper. The results show that the recoveries of SiO2 are lower than 92. 5% when the content of Na is higher than 300 mg/L. The matrix interference effect and the instrument fluctuation have been overcome by Au internal calibration with improved precision and accuracy of the analysis. The determination limit of SiO2 was 0.0075 mg/L and the determination content range was of 0.025% - 10.0%. The results are in agreement with the certified values of the reference materials and the precision of the method is less than 2% ( RSD, n = 9 ) . Compared with conventional chemical analysis, the measured values of SiO2 are in agreement with the certified values. However, the cumbersome procedure, time consuming, heavy workload of conventional chemical analysis methods can be overcome as the work efficiency is improved with this method. It can also be used for the simultaneous determination of Al, Fe, Ca, Mg and P in chrome ore samples.%以过氧化钠为熔剂,经高温熔融-热水提取-盐酸酸化前处理样品,选用金为内标元素,电感耦合等离子体发射光谱法测定铬矿石中的二氧化硅.试验了熔融试样时引入的基体元素钠对被测元素的干扰情况,结果表明,钠含量高于300 mg/L时,二氧化硅的回收率均低于92.5％.采用金内标法有效克服了基体效应及仪器波动产生的影响,改善和提高了准确度和精密度.二氧化硅的检出限为0.0075 mg/L,测定范围为0.025％ ～10.0％.对铬矿石标准物质进行测定,结果与标准值一致,方法精密度(RSD,n=9)小于2％.与常规化学分析法进行比对试验,二氧化硅的测定值吻合较好,但克服了常规化学分析方法步骤繁琐、耗时长、工作量大的不足,提高了工作效率.本方法也可用于同时测定铬矿石中铝、铁、钙、镁、磷等主次量成分.