Photochemical Vapor Generation of Platinum: Mechanism and Analytical Application

Herein, the photochemical vapor generation (PVG) of platinum was studied in three kinds of media, formic acid (FA), acetic acid (AA), and propionic acid (PA). Results demonstrated that PVG of Pt was more efficient in AA, followed by PA and last by FA. Combining inductively coupled plasma mass spectrometry (ICP-MS) for its detection, a novel analytical method for trace platinum was established. Key parameters were evaluated, including reaction media, sensitizers, UV irradiation time, and carrier gas flow rate. Under the selected conditions, limits of detection (LODs) of 15, 1, and 0.6 ng L^-1, as well as great repeatability (expressed as the RSD of 11 trials) of 4.7% (5 μg L^-1 of Pt), 4.3% (0.5 μg L^-1 of Pt), and 3.5% (0.5 μg L^-1 of Pt) were achieved in the media of FA, AA and PA, respectively. This method was validated by analysis of a certified water sample (BWB2236-2016) and applied for the determination of trace platinum in several water samples, as well as human urine and serum. The generation of certain volatile Pt species, probably Pt(R)_<i>x</i>(CO)_<i>y</i> (R = CH₃ or CH₃CH₂, <i>x</i> and <i>y</i> can be zero or other values), was speculated, which further decomposed and agglomerated into Pt nanoparticles of different sizes as evidenced by transmission electron microscopy (TEM) and may account for the discrepancy in their transportation efficiency and resultant PVG-ICP-MS response.