Simple semiquantitative determination of trace metal ions by use of reagent gel columns-I: determination of mercury with dithizone gel

Mercury(II) at the sub-ppm level was determined by using a column packed with gel beads containing dithizone stabilized as the zinc complex. The beads turned from pink to green when the acidified sample solution was passed through the column. If the solution contained mercury (II), the colour of the gel beads turned to orange owing to the formation of mercury dithizonate. The length of the coloured zone was proportional to the amount of mercury in the sample. With 0.01% dithizone gel, as little as 0.1 ppm of mercury(II) could be determined in a 20-ml sample at a flow-rate of 1 ml/min.