吹扫捕集-气相色谱/冷原子荧光法联用测定地表水中甲基汞研究

建立了吹扫捕集-气相色谱/冷原子荧光联用测定地表水中甲基汞的方法,具体方法:水样乙基化后转化为易挥发的甲基乙基汞,在线吹扫捕集至Tenax管,在高纯Ar作载气时加热使Tenax捕集管中各种形态的Hg热脱附,进入GC柱分离,在700℃~900℃高温下热解还原为元素汞(Hg0),进入冷原子荧光检测器进行检测.方法检出限为0.08 pg(若水样为40 mL,检出限为0.002 ng/L),相关系数可达0.9999.对不同来源的地表水进行分析,精密度<10%,加标回收率在83.4%~105%,具有操作简单、快速、灵敏度高,满足环境监测要求.

Determination of Methyl Mercury in Surface Waters by Purge and Trap Gas Chromatography/Cold Vapor Atomic Fluorescence Spectrometer

A method for detection of methyl mercury in surface waters by purge and trap gas chromatography/cold vapour atomic fluorescence spectrometer was established. The ethylation derivatization converted MeHg to the more volatile methylethylmercury, which could be concentrated through online purge and trap system with Tenax capture tube. With high purity carrier gas Ar, the thermal desorption of various forms of Hg in the Tenax trap tube was heated and methylmercury was pyrolyzed to elemental mercury at high temperature at 700℃ ~900℃,then elemental mercury was detected by cold vapour atomic fluorescence spectrometer. The methyl mercury detection limit is 0. 08 pg(or 0. 002 ng/L for 40mL sample determined). The correlation coefficient can achieve 0. 9999. The precision was less than 10% for different sources of surface water, and the average recoveries rates were between 83. 4% and 105%. This method is simple, rapid, sensitive and suitable for determination of methyl mercury in surface waters.