Stripping voltammetric determination of palladium, platinum and rhodium in freshwater and sediment samples from South African water resources

Abstract

Stripping voltammetry as technique has proved to be very useful in the analysis of heavy and other metal ions due to its excellent detection limits and its sensitivity in the presence of different metal species or interfering ions. Recent assessments of aquatic samples have shown increased levels of platinum group metals (PGMs) in aquatic ecosystems, caused by automobile exhaust emissions and mining activities. The development of an analytical sensor for the detection and characterisation of PGMs were investigated, since there is an ongoing need to find new sensing materials with suitable recognition elements that can respond selectively and reversibly to specific metal ions in environmental samples. The work reported shows the successful application of another mercury-free sensor electrode for the determination of platinum group metals in environmental samples. The work reported in this study entails the use of a glassy carbon electrode modified with a bismuth film for the determination of platinum (Pt(2+)), palladium (Pd(2+)) or rhodium (Rh(2+)) by means of adsorptive cathodic stripping voltammetry. Optimised experimental conditions included composition of the supporting electrolyte, complexing agent concentration, deposition potential, deposition time and instrumental voltammetry parameters for Pt(2+), Pd(2+) and Rh(2+) determination. Adsorptive differential pulse stripping voltammetric measurements for PGMs were performed in the presence of dimethylglyoxime (DMG) as complexing agent. The glassy carbon bismuth film electrode (GC/BiFE) employed in this study exhibit good and reproducible sensor characteristics. Application of GC/BiFE sensor exhibited well-defined peaks and highly linear behaviour for the stripping analysis of the PGMs in the concentration range between 0 and 3.5 μg/L. The detection limit of Pd, Pt and Rh was found to be 0.12 μg/L, 0.04 μg/L and 0.23 μg/L, respectively for the deposition times of 90 s (Pd) and 150 s (for both Pt and Rh). Good reproducibility was also observed and the practical applicability of the sensor was demonstrated with the analysis of environmental water and sediment samples.

Quantification of Noble Metals in Biological and Environmental Samples

“…Close reduction peak potentials and severe matrix effects limit direct application of AV for simultaneous detection of PGMs. Optimizing the electrolyte composition can allow simultaneous detection of Pt, Pd, and Rh [101] and of Pt and Rh [102]. AV is extremely sensitive to organic matrices.…”

Bismuth–silver bimetallic nanosensor application for the voltammetric analysis of dust and soil samples

“…An Agilent 7500 series inductive coupled plasma mass spectroscopy (ICP-MS) was used for the trace PGMs determination in roadside dust and soil samples. All experiments were performed in a 20 mL electrochemical cell at conditioned room temperature [10,[30][31][32][33].…”

“…In the literature for the determination of PGMs using voltammetric techniques, a large number of papers involve the use of hanging mercury drop electrode as the working electrode [5][6][7]. Only in a few cases other electrodes such as modified carbon paste electrodes [8,9] and bismuth film electrodes [10,11] were used. According to the literature palladium, cobalt and nickel react with dimethylglyoxime (DMG) to form 1:2 complexes, e.g.…”

Speciation Analysis of Chloroplatinates

“…Švancara et al (2007) applied a carbon pase electrode modified in situ with cationic surfactants for the determination of platinum metals via suitable complex ions. Adsorptive differential pulse stripping voltammetric measurements for Pt(II) were performed in freshwater and sediment samples in the presence of dimethylglyoxime as complexing agent (van der Horst et al 2012). The glassy carbon bismuth film electrode (GC/BiFE) exhibited good and reproducible sensor characteristics.…”