基于氧化/吹扫捕集-冷原子荧光光谱法测定海水中痕量总汞

Determination of trace total mercury in seawater by oxidation/purge and trap-cold atomic fluorescence spectrometry

基于氧化/吹扫捕集-冷原子荧光光谱法,建立了准确测定海水中痕量总汞的方法.采用硫酸和过硫酸钾体系氧化海水样品,盐酸羟胺预还原,再经氯化亚锡将全部的汞离子还原为单质汞,原位吹扫和金汞齐捕集,在波长253.7 nm处原子荧光光谱法分析测定.结果表明:该方法回收率为94%—104%,精密度相对标准偏差为2.1%—3.6%,方法检出限为0.1 ng·L^(−1),测定下限为0.4 ng·L^(−1),与现行国标方法相比,该方法增加了原位吹扫捕集的前处理步骤,因而灵敏度更高,检出限更低,也具有很好的稳定性.用不同海区实际海水样品进行验证,结果显示,该方法满足实际样品的分析需求,建议在海水水质的汞监测领域能够拓展应用.

Based on the oxidation/purge and trap-cold atomic fluorescence spectrometry,a method for the accurate determination of trace total mercury in seawater was developed in this paper.The seawater sample was oxidized by sulfuric acid and potassium persulfate system,pre-reduced by hydroxylamine hydrochloride,and then reduced to elemental mercury by stannous chloride.The mercury ion was purged in the same position and trapped by gold amalgam.It was analyzed and determined by atomic fluorescence spectrometry at the wavelength of 253.7 nm.The results showed that the recovery was 94%—104%,the relative standard deviation of precision was 2.1%—3.6%,the detection limit was 0.1 ng·L^(−1),and the lower limit of determination was 0.4 ng·L^(−1).Compared with the current national standard method,the developed method has higher sensitivity,lower detection limit,and better stability.The method was validated by actual seawater samples from different sea areas,and the results showed that the method meets the analysis requirements of actual samples.Therefore,it is expected that the method can be widely used in the mercury determination of sea water.