AUTOMATED-DETERMINATION OF MERCURY BY CONTINUOUS-FLOW VAPOR GENERATION AND COLLECTION IN A GRAPHITE TUBE

A procedure for the automated determination of mercury involving continuous flow vapour generation followed by collection on a gold-platinum gauze and direct re-vaporization in the tube of a graphite furnace is presented. Statistical evaluation of a calibration function rendered a limit of determination of 35 pg, corresponding to a concentration of 3.5 ng l-1 in a 10 ml sample volume. Comparison of amalgamation in the graphite atomizer with external amalgamation and transfer to a quartz cuvette demonstrated the higher rate of atom generation in the graphite tube and the absence of transport broadening. A reproducibility better than 1.0% for volumes up to 50 ml was reached using a continuous flow system. No interference due to 150 mug l-1 of the hydride forming element arsenic on the trapping and re-vaporization rate of Hg in the graphite tube was detectable.