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A highly sensitive, catalytic adsorptive stripping voltammetric procedure at the hanging mercury drop electrode for the simultaneous determination of ultratraces of platinum and rhodium in electrolyte solutions has been evaluated. Optimal conditions were found to be: first accumulation potential 0 V (vs. Ag/AgCl), second accumulation potential −0.8 V, first preconcentration time 90 s, second preconcentration time 120 s, scan rate 20 mV s−1. The response of the system was found to be linear in a range of platinum concentrations up to 6 ng l−1 and for rhodium up to 0.5 ng l−1. The detection limit was 21 pg l−1 for platinum and 5.6 pg l−1 for rhodium. The effect of various possible interferences from other metal ions was also studied. With the exception of zinc (whose influence was studied in more detail), no significant interferences were observed. The method was successfully applied to the determination of traces of Pt and Rh in real environmental samples (spruce shoots) after high pressure digestion.

By introducing the exhaust gas converters in automobiles (in 1975 in the USA and in Germany in 1984) the emission of combustion based pollutants (e.g., NOx, HCH) and of lead have been significantly reduced. But materials used in the catalysts (initially mainly Pt, later in various ratios also other Platinum Group Metals (PGM) such as Pd and/or Rh and nowadays often only Pd and some transition metals as promotors) are increasingly being introduced into the environment. Many efforts have been made to study the influence of the trace metals in the environment. At first it was necessary to develop powerful analytical techniques to determine precisely high concentrations in polluted samples as well as ‘natural’ background concentrations at much lower levels. Table 2 and 3 presents an overview of concentration ranges of Pt and Rh found in various materials in the last years.

A very sensitive procedure for the determination of baseline levels of platinum is presented. A high-pressure digestion step of the sample is followed by the determination via adsorption voltammetry and detection by a catalytic hydrogen wave. Interferences and blank value problems are discussed.