Sensitive and selective determination of mercury by differential pulse stripping voltammetry after accumulation of mercury vapour on a gold plated graphite electrode

 A selective and sensitive method is proposed for the determination of mercury by anodic stripping voltammetry after its preconcentration from the gas phase. Mercury from the sample solution is reduced to elemental Hg by SnCl₂ and volatilized by the bubbles of a carrier gas. The gas containing mercury vapour is dried and passed through a capillary onto a gold coated graphite electrode. An anodic stripping voltammogram is recorded from 0.1 mol/l HClO₄+3×10^-3 mol/l HCl solution. The calibration curve is linear from 1×10^-9 to 4×10^-8 mol/l Hg(NO₃)₂. The absolute detection limit is 0.46 ng Hg. The relative standard deviations for 4×10^-9 mol/l and 2×10^-8 mol/l Hg(NO₃)₂ are 9.8% and 6.1%, respectively (n=5). Received: 18 December 1995/Revised: 16 April 1996/Accepted: 20 April 1996