建立了一种用抗坏血酸-磺胺双络合体系进行氢化物原子荧光光谱法测定土壤中镉的新方法。研究了抗坏血酸-磺胺双络合体系对方法的增效作用,以及Ni2+对测定的显著增感作用;探讨了氢化物发生的反应机理,并应用核磁共振仪对机理进行实验验证。该方法测镉的最佳条件为:以3%HCl为载流,20g/LKBH4溶液为还原剂,在0.05%抗坏血酸+0.05%磺胺双络合试剂+0.1mg/LNi2+体系中,镉的线性范围为2~40μg/L,相关系数(r)0.9993,检出限为0.08μg/L,RSD〈4.8%(n=14)。应用本方法测定了4种国家土壤标准物质中镉的含量,结果与标准值吻合。
A novel system was developed for the determination of Cd in soil samples using hydride generation atomic fluoresce spectroscopy.Some complexing reagents and transition metal ions were tested as enhancement reagents respectively.The results showed that an appropriate amount of ascorbic acid and sulfanilamide added simultaneously could effectively improve the vapor generation efficiency of Cd.The volatile species was generated noticeably when nickel ion was added.The principle of hydride generation of cadmium was discussed,and verified by nuclear magnetic resonance method.The optimal detective conditions were that the double complexing reagent concentrations of ascorbic acid and sulfanilamide were all in 0.05%,and Ni2+was 0.1 mg/L when the instrument condition was in 3%HCl as a carrier flow,and 20 g/L of KBH 4 as a reductant.The limit of detection(LOD,3σ) was 0.08μg/L and the linear range was 2-40μg/L.The relative standard deviation(RSD) was less than 4.8%(n=14) .The method was successfully applied for the determination of trace Cd in the four national standard reference materials(GBW07428,GBW07402,GBW07404 and GBW07408) and the results analyzed were in good agreement with the certified values.