Iodine determination by ICP-MS following platinum-assisted photochemical vapor generation: a strategy to overcome condensed-phase interferences

Abstract

Data on the use of Pt²⁺ in the ion-assisted photochemical vapor generation of iodine with detection using inductively coupled plasma mass spectrometry (ICP-MS) are presented. Certified reference materials (antarctic krill, milk powder and oyster tissue) were acid-digested using a mixture of HNO₃ and H₂O₂ and subsequently spiked with 0.5 mg L⁻¹ Pt²⁺. The digested samples were then diluted to contain 10% (v/v) CH₃COOH and irradiated using a Hg lamp with the main emission line at 253.7 nm in a quartz photoreactor. The nitric acid interference on the photochemical generation of volatile iodine species was evaluated in the range 0–5% (v/v). Signal suppression, likely due to NO₃⁻ and/or the formation of NO₂⁻, was overcome for solutions containing between 0.3 and 0.7 mol L⁻¹ HNO₃ upon adding Pt²⁺ to the solution. The presence of Pt²⁺ has also provided a ca. 85% signal enhancement for iodine in comparison with solutions without Pt²⁺. The samples were analyzed following calibration against aqueous standards, which is a definite advantage over many PVG methods reported in the literature and further evidence of Pt²⁺ efficiency in suppressing condensed phase interferences under the adopted conditions. The determined analyte concentrations in the CRM were all in good statistical agreement with the certified values, demonstrating the good accuracy of the method.