微波消解-电感耦合等离子体原子发射光谱法测定钒钛铁精矿中钾和钠

Determination of potassium and sodium in vanadium-titanium-iron concentrate by microwave digestion-inductively coupled plasma atomic emission spectrometry

采用微波消解法以盐酸-氢氟酸-水体系处理样品,选择K 769.896nm、Na 588.995nm为分析谱线,建立了使用电感耦合等离子体原子发射光谱法(ICP-AES)测定钒钛铁精矿中钾和钠的方法。实验表明:采用8.0mL盐酸-5.0mL氢氟酸-5.0mL水以微波消解法可将0.500 0g钒钛铁精矿试样溶解完全。铁基体对钠的测定基本无影响,但对钾的测定影响较大,不可忽略,故实验在绘制校准曲线用标准溶液系列中加入与测试样品所含铁基体大致相当的铁基体溶液以消除铁基体效应的影响。钾和钠的质量分数分别在0.006%~0.08%、0.005%~0.04%范围内与其发射强度呈线性,校准曲线线性相关系数分别为0.999 8、0.999 9;方法检出限钾为0.03%,钠为0.02%。方法应用于钒钛铁精矿标准样品中钾和钠的测定,测定值与认定值相符,相对标准偏差(RSD,n=10)均小于5%。

The sample was treated in hydrochloric acid-hydrofluoric acid-water system by microwave diges-tion method. K 769. 896 nm and Na 588. 995 nm were selected as the analytical lines. A determination method of potassium and sodium in vanadium-titanium-iron concentrate was established by inductively cou-pled plasma atomic emission spectrometry （ICP-AES）. The results showed that 0. 500 0 g of vanadium-ti-tanium-iron concentrate sample could be completely dissolved by microwave digestion with 8. 0 mL of hy-drochloric acid, 5. 0 mL of hydrofluoric acid and 5. 0 mL of water. The iron matrix did not have influence on determination of sodium, but have great influence on determination of potassium which could not be ig-nored. The iron matrix solution which was roughly equivalent to that in test sample was added to standard solution series for calibration curves to eliminate the influence of iron matrix effect. The mass fraction of potassium and sodium in range of 0. 006%-0. 08% and 0. 005%-0. 04% were linear to their corresponding emission intensity with linear correlation coefficients of 0. 999 8 and 0. 999 9, respectively. The detection limit of potassium and sodium was 0. 03% and 0.02%, respectively. The proposed method was applied to the determination of potassium and sodium in certified reference material of vanadium-titanium-iron con-centrate, and the results were consistent with the certified values. The relative standard deviations （RSD, n=10） were less than 5%.