电感耦合等离子体质谱法测定硫时不同形态硫的影响

The Effect on Sulfur Species during Determination of Sulfur by Inductively Coupled Plasma-Mass Spectrometry

电感耦合等离子体质谱(ICP-MS)常常被应用于矿石、蛋白质和化石燃料等材料中硫含量的测定。文章综合研究比较了四极杆电感耦合等离子体质谱(Q-ICP-MS)和扇形磁场电感耦合等离子体质谱(SF-ICP-MS)测定硫的灵敏度、检出限及空白干扰。重点考察了两种不同的样品介质(水和2%HNO3)中不同形态的硫对SF-ICP-MS测定硫信号的影响,并且深入研究了影响的原因。结果表明,硫含量相同但形态不同的含硫阴离子(S2-、S2O32-、SO32-、SO42-)在2%的HNO3介质中的信号比在水介质中的信号稳定,2%的HNO3更适合于作为ICP-MS测定硫的介质。在2%的HNO3介质中,S2-、SO23-中S的ICP-MS测量灵敏度(即标准曲线的斜率)分别为7828 cps/(μg.L-1)、5528 cps/(μg.L-1),SO42-和S2O23-的测量灵敏度分别是为1321 cps/(μg.L-1)、1299 cps/(μg.L-1)。S2-和SO23-的灵敏度分别约为SO24-的6倍和4倍;而S2O23-的灵敏度与SO42-基本一致。主要原因在于S2-、SO23-形态的硫在HNO3介质中形成了气态的H2S和SO2,相当于提高了雾化效率,从而使这两种形态硫的灵敏度大幅度提高。

Inductively Coupled Plasma-Mass Spectrometry （ICP-MS） is often applied to determine sulfur in minerals, proteins, fossil fuels and other materials. The study of sensitivity, limit of detection and background noise during determination of sulfur, using both Qnadrupole Inductively Coupled Plasma-Mass Spectrometry （Q-ICP-MS） and Sector Field Inductively Coupled Plasma-Mass Spectrometry （SF-ICP-MS）, are presented in this paper. One focus of the paper is to study the effect on sulfur species during determination of sulfur in two different matrices （water and 2% HNO3 ） by SF-ICP-MS. The results indicate that the signals for S2- , S2O32-, SO23- , SO2- , respectively, in 2% HNO3 are consistently more stable than in water matrix. Therefore, the matrix of 2% HNO3 is more suitable for sulfur determination by ICP-MS. In addition, sulfur sensitivities for S2- [7828 eps/（μg L-1） and SO3^2- [5528 cps/（ μg L-1） ] were higher than those for SO]- [ 1321 cps/（ μg L-l） ] and S2O23- [ 1299 eps/（ μg L-1） ] by ICP-MS. The sulfur sensitivities of S2- and SO23- were 6 and 4 times higher respectively than those of S2O32- and SO2- The reason for higher sulfur sensitivities for both S2- and SO23- is that the formation of aerosols （H2S and SO2 ） in 2% HNO3 improves atomization efficiency.