微波消解-电感耦合等离子体原子发射光谱法测定菱镁矿中10种主量元素

菱镁矿中镁、钙、硅、铁、铝、钾、钠、锰、钛、磷等10种主量元素含量范围相差较大，同时分析多元素比较困难。使用盐酸-硝酸-氢氟酸酸溶体系并采用微波消解法消解样品，并选择钇为内标元素，采用耐氢氟酸进样系统的电感耦合等离子体原子发射光谱法(ICP-AES)测定了菱镁矿中镁、钙、硅、铁、铝、钾、钠、锰、钛、磷等10种主量元素。各元素校准曲线线性相关系数均大于0.999;方法检出限为0.000 5%～0.028%。按照实验方法测定5种菱镁矿成分分析标准物质中镁、钙、硅、铁、铝、钾、钠、锰、钛、磷，结果的相对标准偏差(RSD,n=6)为0.35%～4.9%,且与认定值相一致。按照实验方法测定菱镁矿实际样品中10种元素，与重量法测定硅、滴定法测定镁及敞口酸溶-ICP-AES测定其他8种元素进行方法比对，结果无显著性差异。微波消解方式用酸量小，不引入杂质、同时保留了硅在溶液中，解决了菱镁矿中硅与其他主量元素不能同时测定的问题，内标法的使用提高了高含量镁测定的精密度，为菱镁矿的快速准确测定提供了新的途径。

Determination of 10 major elements in magnesite by microwave digestion-inductively coupled plasma atomic emission spectrometry

The content range of ten major elements in magnesite (including magnesium, calcium, silicon, iron, aluminum, potassium, sodium, manganese, titanium, and phosphorus) has great difference. Therefore, the simultaneous analysis of multi-elements is relatively difficult. The sample was treated by microwave digestion in hydrochloric acid-nitric acid-hydrofluoric acid system. Yttrium was selected as the internal standard element. The contents of ten major elements in magnesite, including magnesium, calcium, silicon, iron, aluminum, potassium, sodium, manganese, titanium, and phosphorus, were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) with hydrofluoric acid resistant injection system. The linear correlation coefficients of calibration curves of elements were all higher than 0.999. The limits of detection were 0.000 5%-0.028%. The contents of magnesium, calcium, silicon, iron, aluminum, potassium, sodium, manganese, titanium, and phosphorus in five certified reference materials of magnesite were determined according to the experimental method. The relative standard deviations (RSD, n=6) of determination results were between 0.35% and 4.9%. The found results were consistent with the certified values. Ten elements in magnesite sample were determined according to the experimental method. Meanwhile, silicon was also determined by gravimetry, magnesium was determined by titration method, and other eight elements were determined by ICP-AES after open acid dissolution. The method comparison showed that the found results had no significant difference. The consumption of acid in microwave digestion was small. Moreover, no impurity was introduced and silicon could be remained in the solution, which solved the problem that silicon and other major elements could not be determined simultaneously. The use of internal standard method improved the determination precision of high content magnesium. The proposed method provided a new approach for the rapid and accurate determination of magnesite.