石墨炉原子吸收测镉和测铅时消除共存离子干扰的研究

目的探讨石墨炉原子吸收测镉（或铅）时,消除共存金属离子干扰的方法。方法配制每毫升含0.25μg镉（或铅）和250μg其它金属离子模拟样品,向石墨管进样20μL,再直接加入基体改进剂5μL,做消除共存金属离子的干扰效果实验。结果共存金属离子含量远大于被测元素镉（或铅）时,对测镉和测铅存在严重干扰,回收率在30%~76%;在石墨炉原子吸收法测镉时直接向石墨管中添加5%硫酸铵溶液能消除共存金属离子的干扰,回收率达到85%以上;测铅时直接向石墨管中添加2%磷酸二氢铵溶液能消除共存金属离子的干扰,回收率达到87%以上。结论本研究是石墨炉原子吸收法测镉和铅时消除共存金属离子干扰的一种快速、灵敏、准确的分析方法。适用于生活饮用水、污水、食品等分析。

Elimination of coexistent metal ion interference in determination of cadmium and lead by GFAAS

Objective To establish the method for determination of cadmium and lead by GFFAS with elimination of coexistent ion interference.Methods Simulated samples containing 0.25 μg cadmium（or lead） and 250 μg other metal ion per milliliter were prepared,putting 20μL into the graphite tube,and then directly adding 5 μL matrix modifier for coexistent elimination of metal ions interference.Results Serious interference on measurement of cadmium and lead was observed in case the content of coexistent metal ions was much larger than the measured cadmium（or lead）,with recovery rate of between 30% to 76%.In the determination of cadmium with graphite furnace atomic absorption spectrometry,5% ammonium sulfate solution was directly added into the graphite tube with the recovery rate of more than 85%.For determination of lead,2% phosphoric acid two ammonium hydroxide solution directly added to the graphite tube with recovery rate of above 87%.Conclusion This method is rapid,sensitive,and accurate for determination of lead and cadmium with suppression and elimination of coexisting metal ions interference,which is suitable for analysis of drinking water,sewage and food.