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Abstract: Adsorptive stripping voltammetry (‘formazone-method’) is already known as one of the most sensitive methods for platinum analysis with a detection limit in the low picograms range. In this work, it is shown that the detection limit can be lowered even more by one order of magnitude to 0.2pg (=1fmol) Pt in 15mL electrolyte, corresponding to 68fmol/L, by applying forced convection during the stripping step of the voltammetric measurement. The sensitivity of the method (given in nA/pg Pt) is enhanced by a factor of 3–5 (in differential pulse mode and 15mL vial), up to a factor of 30 (using square-wave mode and 3mL vial). The maximum enhancement factor is limited by the maximum stirrer speed, which can be applied without negative effects on the hanging mercury drop electrode. To check for similar enhancement effects in other types of stripping methods, the behaviour of adsorptive stripping voltammetry for Pt is compared to conventional anodic stripping voltammetry (ASV) of lead, and to adsorptive stripping voltammetry of nickel and cobalt using their dimethylglyoxime (DMG) complexes. No enhancement effect is observed in ASV of lead upon stirring, and the nickel-DMG-system exhibits only a smaller enhancement factor of about 1.5. A reasonable explanation of the higher signal enhancement in the catalytic Pt–formazone-system is the mass transport of reaction products, namely hydrogen, away from the working electrode during the catalytic hydrogen evolution cycle. [Copyright &y& Elsevier]

Abstract: The uptake and bioaccumulation of the platinum group metals (PGM) platinum (Pt), palladium (Pd), and rhodium (Rh) by the zebra mussel (Dreissena polymorpha) were investigated in exposure studies using ground material from unused automobile catalytic converters as metal source. The mussels were exposed to the metals in tap water or humic water. In the soft tissue samples of exposed mussels mean Pt levels ranged in dependence on the type of tank water and the exposure period (6, 9, or 18 weeks) between 780 and 4300ng/g, the Pd levels ranged between 720 and 6300ng/g, and the Rh levels ranged between 270 and 1900ng/g. In contrast, the control mussels had metal concentrations of <20ng/g (Pt), <50ng/g (Pd), and <40ng/g (Rh). Considerably higher PGM levels were found in the exposed mussels of the humic water group than in those of the tap water group. Although there is a cumulative increase of the PGM concentrations in the environment since the introduction of the automobile catalyst more than 20 years ago, only little information about the PGM contamination in the biosphere, especially the fauna, is available. Due to the high capacity of D. polymorpha to accumulate PGM, this bivalve could be used as a potential sentinel for monitoring the noble metals in aquatic ecosystems. [Copyright &y& Elsevier]

The bioaccumulation of Pt, Pd and Rh by grass grown hydroponically with nutrient solutions containing these ions at elevated (38.7 mg l−1 Pt, 21.7 mg l−1 Pd and 7.1 mg l−1 Rh) and medium (3.6 mg l−1 Pt, 4.4 mg l−1 Pd and 0.5 mg l−1 Rh) concentrations was studied by using inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The highest bioaccumulation factors were obtained for Pd and Rh in roots and for Pt in leaves. The obtained results showed that most of the studied metals were accumulated in roots, and only a small fraction was really metabolised and transported to leaves. The multi-element capability of ICP-SFMS has been exploited to study the metabolism of platinum group elements (PGEs) in cultivated plants. The species of studied metals were extracted from roots and leaves and separated into two mass fractions by ultra-filtration. The low molecular mass (<10 kDa) fractions of the root and the leaf extracts were investigated by size-exclusion chromatography (SEC) coupled on-line to ICP-SFMS. The presence of Ca, Cu, S and C in the same fractions as Pt, Pd and Rh may indicate the interaction of PGEs with phytochelatins and carbohydrates. [Copyright &y& Elsevier]

In the present study, we evaluated a microwave digestion procedure followed by electrothermal atomic absorption spectrometry (ET-AAS) for the determination of the platinum group metals (PGM) Pt, Pd and Rh in small amounts of animal tissue. Due to the lack of certified biological standard reference materials for PGM, we performed interlaboratory comparisons using adsorptive cathodic stripping voltammetry (ACSV) after digestion of the samples by high pressure ashing (HPA) for the determination of Pt and Rh and total-reflection X-ray fluorescence (TXRF) analysis after co-precipitation of Pd with mercury for the determination of Pd, as reference methods. Suitable sample materials were obtained from laboratory experiments with mussels exposed to PGM salts or ground automobile catalytic converter material.The 3 s detection limits for microwave digestion (MWA)/ET-AAS were 270 ng g−1 (Pt), 90 ng g−1 (Pd) and 13 ng g−1 (Rh), the precision was better than 10% and the recovery was >95%. The highest divergence between the MWA/AAS and HPA/ACSV/TXRF procedures was found for Pt with values of 48 and 26%. But, even though the Pt levels exceeded the detection limit, the concentrations were near to or below the limit of determination (three times the detection limit). In contrast to Pt, the results of the different analytical procedures for Pd and Rh were comparable (<20% deviation).The combination of MWA and ET-AAS is a very rapid and relatively cheap method for routine PGM analysis in large numbers of animal tissue samples with PGM concentrations exceeding the upper ng g−1 range as occur e.g. in experimental studies or in the medical sector after treatment with Pt-anti-cancer drugs. [Copyright &y& Elsevier]

The uptake and bioaccumulation of 15 road dust metals by the zebra mussel (Dreissena polymorpha) were investigated in laboratory exposure studies with emphasis on the traffic-related platinum-group elements (PGEs) palladium (Pd), platinum (Pt), and rhodium (Rh). The biological availability of the metals may depend on water characteristics, so the mussels were maintained in two types of water: nonchlorinated tap water and humic water of a bog lake, both of which contained dust of a moderately frequented road. After an exposure period of 26 weeks, soft tissues of the mussels were freeze-dried and analyzed for the metals. The metal concentrations in the mussel soft tissue ranged from several hundred micrograms per gram (e.g., for iron [Fe]) to less than 10 ng/g (for PGEs). Metal uptake from the road dust by the mussels was found for the PGEs and silver (Ag), bismuth (Bi), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), Fe, lead (Pb), and antimony (Sb). After maintenance of mussels in road dust-contaminated tap water, bioaccumulation factors (BAF = (cexposed mussels - ccontrol mussels)/ctotal metal, water; where c is concentration) decreased in the following order: Cu > Cd > Ag > Pd > Sb > Pb > Fe > Pt > Rh. The biological availability of most metals was enhanced by humic water as compared to tap water. Our results show a hitherto unrecognized high availability of Pd for the mussels. Thus, this metal should be monitored more intensively in the environment to assess its distribution in the biosphere. [ABSTRACT FROM AUTHOR]