Development of a 'collect and punch' cold vapour inductively coupled plasma mass spectrometric method for the direct determination of mercury at nanograms per litre levels

A highly sensitive 'collect and punch' CV-ICP-MS method for the direct determination of mercury at ng l(-1) levels is described. Mercury, after reduction to elemental form with SnCl2, was collected in a glass chamber prior to injection into the plasma and the time resolved acquisition mode was used for signal measurement. This arrangement provided a 10-15-fold enhancement of sensitivity compared with continuous vapour injection. The detection limit (3s) of the method was close to 6 ng l(-1). Linear calibration was obtained over three orders of magnitude of concentration. The method was validated through the analysis of NIST SRM 1566a Oyster Tissue. Mercury at the 50 ng l(-1) level in aqueous solutions can be determined with a precision of approximately 2%. This method is much simpler than the amalgamation approaches for the determination of mercury at these levels.