Investigations on extraction procedures for Pt species from spiked road dust samples using HPLC–ICP–MS detection

For the optimisation of the extraction procedures PtCl42- and PtCl62- were used as model species for extractable Pt(II)- and Pt(IV)-compounds in road dust. A previously developed ion exchange chromatography–ICP–MS method was applied for the quantification of the Pt species in the extracts. A concept in three steps was realised. First, the stability of the model species in several extractants like HCl, methionine, EDTA and thiourea was studied under variation of the concentrations of the extracting agents, the pH and the supply of energy (refluxing, exposure to microwaves, sonication). Second, spiked road dust samples were extracted with those solvents that provided good results in the first step. The results from samples spiked with a mixture of both model species were compared to analogous extractions from dust samples which were spiked with only one of the chloroplatinates. Moreover, the extractant-to-dust-ratio was optimised. Third, the optimised procedures from the second step were applied to unspiked dust samples originating from two different road tunnels in order to characterise the extractable Pt species. The results of the optimisation proved that the model species are fairly stable in the extractants in the absence of the dust matrix. However, the recoveries of PtCl42from the spiked dust samples were significantly lower and PtCl62- could not be recovered without transformation at all. The extraction efficiencies for total Pt from the unspiked samples were below 5%. The concentrations of the model species in the extracts of these samples were below the limit of detection of the applied HPLC–ICP–MS method. For quality control mass balances of total Pt were established for all extractions.