碱熔-电感耦合等离子体原子发射光谱法测定地质样品中硫

对于成分复杂含硫量高的土壤以及矿石样品,采用敞口酸溶时,由于样品溶解不完全从而造成硫的测定结果偏低。实验采用3.0g氢氧化钠为熔剂,在750℃马弗炉熔融8min,可以将0.500 00g样品熔解完全;使用沸水提取后,加入酒石酸掩蔽碱金属以及二价金属离子,使用盐酸酸化并稀释溶液,最终采用电感耦合等离子体原子发射光谱法(ICP-AES)测定地质样品中硫。校准曲线的线性相关系数大于0.999,方法检出限为35μg/g。实验方法用于测定土壤、水系沉积物、岩石标准物质中硫,测定结果的相对标准偏差(RSD,n=12)为1.6%～5.0%;硫的测定值与认定值基本一致,相对误差均不大于4.6%。按照实验方法测定硫含量高的土壤和岩石实际样品,测定结果的RSD(n=12)不大于1.6%。方法可以有效解决硫含量高的难熔样品中硫的测定问题,经过碱熔-酸化处理后的样品溶液通过调节pH值还可以用于氟离子选择性电极测定氟。

Determination of sulfur in geological samples by inductively coupled plasma atomic emission spectrometry after alkali fusion

For the soil and ore samples with complex composition and high sulfur content, the determination results of sulfur will be lower in the case of open acid dissolution due to incomplete sample digestion. 3.0g of sodium hydroxide was used as flux. 0.50000g of sample could be completely fused after melting in muffle furnace at 750℃ for 8min. After leaching with boiling water, the alkali metal and divalent metal ions were masked by adding tartaric acid. The solution was acidified with hydrochloric acid and then diluted. The content of sulfur in geological sample was finally determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The linear correlation coefficient of the calibration curve was higher than 0.999. The limit of detection was 35μg/g. The experimental method was applied for the determination of sulfur in certified reference materials of soil, stream sediment and rock. The relative standard deviations (RSD, n=12) of determination results were between 1.6% and 5.0%. The found results of sulfur were basically consistent with the certified values, and the relative errors were not more than 4.6%. The actual samples of soil and rock with high content of sulfur were determined according to the experimental method. The RSDs (n=12) of determination results were not more than 1.6%. The proposed method could effectively solve problem for the determination of sulfur in refractory samples with high content sulfur. After treatment by alkali fusion and acidification, the sample solution could be used for the determination of fluorine by fluoride ion selective electrode method after adjusting the pH.