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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.

Differential pulse cathodic stripping voltammetry (DPCSV) was used to determine ultra trace platinum in gasoline after Wickbold combustion and subsequent UV digestion. A commercially available Wickbold combustion apparatus was slightly modified and used to mineralize the gasoline samples. Because a sufficiently high chloride concentration is necessary to avoid Pt losses, the chloride concentration in the condensate was increased by adding HCl vapor to the oxygen stream. The sample solution obtained from the Wickbold combustion still contained some organic compounds which were eliminated using an UV digestion (T > 90 °C, t > 90 min) prior to the electrochemical determination. The recovery was > 87% Platinum concentrations in the order of 5 pg g−1 were found in the analyzed gasoline samples (unleaded Normal, Super and Super Plus). Inductively coupled plasma mass spectrometry was used for comparative measurements.

An argon glow discharge acts as a reactive chemical cell involving sputtered analyte and argon atoms and ions. The spatial distribution of atoms from several samples has been monitored by an atomic absorption and emission arrangement simultaneously with mass spectrometric monitoring of the discharge. We have examined the effect of varying the sample to exit orifice distance on resultant atom profiles. Copper was studied by atomic absorption and iron by atomic emission, revealing complementary population shifts near the cathode surface. Argon metastable species were also monitored and correlated with the analyte response. Movement of the sample insertion probe by 90{degree} allowed a vertical perspective to be obtained for the discharge atom population. The effect of different discharge voltages was also examined to show sputter variations. Atom populations are defined by many factors, including sputter rate, diffusion rates, chemical reactivity, and discharge pressure. 15 refs., 8 figs.

The use of a commercially available AAS graphite tube atomizer as an electrode for the cathodic electrodeposition of element traces at constant-current in a hydrodynamic flow-through-system is described. After deposition the graphite tube is transferred into an atomizer unit for subsequent sensitive determination by atomic absorption spectrometry. The deposition yield of ≥99% (2 h; 1.5 A) for Co was verified, using60Co as a radioactive tracer, by monitoring the concentration fall in the electrolyte solution down to ≤5 pg/ml, and the deposited material. The efficiency of the system for the purification of electrolyte solutions was found to be very high. For the determination of the residual impurities, e.g. in very concentrated NH4F-solutions, a simple ion-exchange procedure was worked out for Cu, Mn, Ni, Pb, Zn. To get back the high purity solid NH4F, the solvent was evaporated partly and the precipitated crystals were sucked off in a PTFE-funnel. To avoid contamination, crystallization was carried out in a closed container system using the principle of subboiling distillation. The purity of the recrystallized NH4F-salt increased by a factor of 2 to 3 (crystallization yield 50–70%) so that a solid product with an impurity level below 0.5 ng/g was obtained.

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.

Die Erfassung des Belastungszustandes unserer Umwelt hinsichtlich anthropogen eingetragener Stoffe gewinnt zunehmend an Bedeutung. Von den etwa 16–17.106 verschiedenen, inzwischen bekannten und somit potentiell in die Umwelt eingetragenen Stoffen lassen sich nur wenige analytisch erfassen und die Zahl der in groserem Umfang kontinuierlich analysierten Substanzen beschrankt sich auf einige wenige, derzeit als in verschiedener Hinsicht problematisch erachteter Analyten.

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.