预富集-石墨炉原子吸收法连续测定饮料中痕量铅和镉

Determination of Lead and Cadmium in Beverage by Using Graphite Furnace Atomic Absorption Spectrometry after Pre-concentration

建立一种连续测定饮料中痕量铅和镉的新方法。以吡咯烷二硫代氨基甲酸铵(APDC)为配位剂,用活性炭在pH4.0～7.0的条件下捕集、抽滤分离Pb-APDC、Cd-APDC配合物,然后用1mL洗脱液(HNO3质量分数为0.2%、NH4H2PO4质量浓度为10g/L)洗脱,超声振荡5min后得可直接上机测定的悬浊液。结果表明:在100mL饮料样品中Pb、Cd的特征质量分别为2.50×10-12g和6.94×10-13g。当n=6时,样品测定的铅和镉的标准偏差为0.0018～0.0055,相对标准偏差为3.04%～6.12%,加标回收率为97.9%～107.0%。该方法具有较高的准确率和富集效率、快速简单、灵敏可靠,结果较为理想。可用于测定饮料中痕量的铅和镉。

A method was developed for the determination of lead and cadmium in beverage by graphite furnace atomic absorption spectrometry（GFAAS） after pre-concentration. The trace lead and cadmium ions was chelated with ammonium pyrrolidine dithio carbamate （APDC）, and fixed on active carbon at pH 4.0-7.0. Then the active carbon was collected on through vacuum filtration, washed with 1ml of diammoniumhy drogenosphate solution （10 g/L） containing 0.2% nitric acid, and the suspension was directly used for the determination by GFAAS. Concentration of lead and cadmium in beverage samples was 2.50×10^-12 g, 6.94×10^-13 g respectively, with the relative standard deviation（RSD） from 3.04% to 6.21% and spike recoveries from 97.9% to 107.0%. This method could be used to determinate trace heavy metal in beverage.