In later work, Christensen et al.13 demonstrated
the suitability of amalgamated
metals as reductants in RPSA. The amalgams
were electrolytically generated from
dissolved metals in a mercury pool. During
stripping, the reductant, which was stored
inside the working electrode, reacted with
sparingly soluble mercury compounds of the
analytes preconcentrated at the electrode
surface (Figure 9). With amalgamated sodium,
the technique proved to be suitable for
the determination of selenium and sulfur at
the 10–7 M level with a 1- to 2-min preconcentration.
Halides can be determined at the
10 –6 M level with a few seconds of
preconcentration and use of a less powerful
reductant such as amalgamated zinc.