Speciation of mercury by liquid separation hydride generation ICPMS

The need for an analytical method to differentiate naturally occurring species of mercury is important, i.e. to understand the distribution and pathways of the highly toxic methylmercury into the food web. The present work aims on determining the two commonest chemical forms of mercury present in environmental samples such as water and sediments, methylmercury (CH3Hg+), and ionic mercury (Hg2+). Liquid chromatography is coupled to ICP-MS in order to reduce sample manipulation to a minimum. The two mercury compounds are separated by reversed-phase chromatography on a non-polar C-18 micro column and eluted with a solution containing acetate, methanol, and mercaptoethanol. A hydride vapour generator device is added between the column and the torch, to increase mercury transport to the plasma. According to literature detection limits around 0,1 ng/L may be expected. The optimization of the LC-vapour generation ICPMS technique and its analytical figures of merit will be presented.