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Determination of sub-picomolar levels of platinum in the Krka River estuary (Croatia)

Platinum (Pt) abundance and distribution on the Earth's surface mainly depends on anthropogenic activities, which accounts for ~80% of Pt fluxes [1], whereas ~45% of produced Pt is used for catalytic converters in cars. Insufficient data on Pt distribution, behaviour and role in aquatic environment placed Pt on the list of potentially eco-toxic elements [2]. One of the reasons for scarce Pt data is extremely low concentration of Pt (<1 pM) in natural waters. Analysis of Pt in natural water requires extremely sensitive analytical techniques, among few, ICP-MS with preconcentration step [3] and catalytic stripping voltammetry [4] are the most widely used. In order to increase the sensitivity using voltammetric analysis, we tested second, third and fourth derivative signal transformation [4]. By using derivative signal transformation and adapted voltammetric procedure we obtained limit of detection (LOD) for real samples of 15 fM, which is even lower then we reported previously [4]. Optimized method was used to determine Pt distribution in the Krka River estuary. Horizontal and vertical profiles (salinity <1 to 39) of Pt were examined in discrete and composite samples. Measured concentrations of Pt are extremely low (<1 pM), among the lowest concentrations found in literature for estuarine systems and ocean waters. Concentrations of Pt gradually increased towards sea end-member, with slight deviation from the conservative mixing line in the region of the urbanized area (Šibenik town) during summer period. In analysed samples Pt was mainly present in dissolved form. References [1] I.S. Sen and B. Peucker-Ehrenbrink, Environ. Sci. Technol. 46 (2012) 8601–8609 [2] A.S. Mashio, H. Obata, T. Gamo, Arch. Environ. Contam. Toxicol. 73 (2017) 240-246. [3] L. Fischer, G. Smith, S. Hann, K. W. Bruland, Mar. Chem. 199 (2018) 44-52. [4] A. Cobelo-Garcia, J. Santos-Echeandía, D. E. López-Sánchez, C. Almécija, D. Omanović, Anal. Chem. 86 (2014) 2308–2313.

Platinum ; Voltammetry ; Marine environment ; Metals & speciation analysis

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