Cold vapour matrix-independent generation and isotope dilution inductively coupled plasma mass spectrometry for reference measurements of Hg in marine environmental samples

The analytical procedure for reference measurements of Hg in marine environmental samples based on cold vapour generation (CVG) inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) and isotope dilution calibration strategy (ID) is described in the present study. The procedure was applied on different matrices and varying mass fractions for mercury in oyster, marine sediment and costal seawater samples. The use of CVG for sample introduction resulted in sensitivity enhancement, reduction of blank levels, minimization of matrix interferences and the elimination of memory effects. The entire measurement process was described by mathematical equations, and all factors influencing the final results were systematically investigated. The expanded uncertainty on results was estimated following the ISO/Guide to the Expression of Uncertainty in Measurement guidelines, and all major contributions were identified. Modelling of the entire measurement process and the use of primary method of measurements ID ICP-MS related obtained values for total mercury in different types of marine matrices to the international system of units SI. Obtained results for mercury mass fractions in biota and marine sediments were used as the International Atomic Energy Agency's contribution in the certification campaigns for marine reference materials and were in excellent agreement with the assigned reference values.