Spectrochimica Acta Part B: Atomic Spectroscopy 177 (2021) 106052 Available online 19 December 2020 0584-8547/© 2020 Elsevier B.V. All rights reserved. Simultaneous determination of platinum group elements and rhenium mass fractions in road dust samples using isotope dilution inductively coupled plasma-tandem mass spectrometry after cation exchange separation Arijeet Mitra a, * , Indra Sekhar Sen a , Christoph Walkner b , Thomas C. Meisel b a Department of Earth Sciences, Indian Institute of Technology Kanpur, Kanpur, UP 208016, India b General and Analytical Chemistry, University of Leoben, Franz-Josef-Str. 18, A-8700 Leoben, Austria ABSTRACT Measurement of Platinum Group Element (PGE: Ru, Rh, Pd, Os, Ir, and Pt) and Rhenium (Re) in environmental samples is a diffcult task due to their ultra-trace level concentrations, and these metals suffer from severe isobaric and polyatomic interference. These kinds of issues have been solved for environmental samples having simple matrices such as tunnel dust and moss. However, a scope of improvement still exists in challenging sample matrices such as road dust, soil, and rocks. In this study, a method that enables measurement of PGE and Re mass fractions in road dust and rock samples is proposed. The method involves matrix removal using a cation-exchange column followed by measurement using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS, also known as ICP- QQQ-MS) with 10% NH 3 in He as reactive gas in Collision/Reaction Cell. This study emphasizes that the usage of a simple cation-exchange column is an important step over the framework developed by Suoranta et al., 2012, which was developed to measure PGE and Re fractions in environmental samples having a simpler matrix such as moss samples. The method combines high pressure (130 bars) and high temperature (220 ◦ C) digestion procedure in combination with isotope dilution (ID) as a calibration strategy, PGE and Re separation using cation exchange resin, and their measurements using ICP-MS/MS. The method was validated with road dust (BCR- 723) and ultramafc komatiite (OKUM) having a complex matrix. The measured PGE and Re mass fractions of the two-measured reference material show excellent agreement with their certifed values and have intermediate precisions ranging from 0.4–7.7% RSD. We conclude that the combination of single-stage cation-ex- change chromatography with ID-ICP-MS/MS measurements enables measurement results with uncertainties ft for purpose for PGE and Re mass fractions in environmental samples with a complex matrix. 1. Introduction Human displacement of platinum group elements (PGE includes platinum (Pt), palladium (Pd) and rhodium (Rh)) on the Earth’s surface are signifcantly higher than those derived from natural sources [1]. As a result, biogeochemical cycling of PGE is perturbed by human activities. The major source of anthropogenic PGE namely Pt, Pd, and Rh are catalytic converters in automobiles [2–4]. These converters are located in the automotive exhaust systems and are used to reduce the emissions of NO x , CO, and unburned or partially burned hydrocarbons from vehicle exhaust systems. During these redox processes, PGE particles are released into the roadside environment by thermal and mechanical abrasion of the device [5–11]. As a result, elevated concentrations of anthropogenically emitted Pt, Pd, and Rh in the roadside environment are of serious concern because they can be hazardous to human health and cause chronic and subclinical diseases. PGE in ≤2.5 μm sized at- mospheric particulate matter (PM2.5) have been attributed to increases in morbidity and mortality [12]. Sen, 2013 [10] predicted the anthropogenic PGE contamination from automobile, two and three wheelers can therefore be substantial in developing countries with a growing automobile industry. Therefore, development of simple, fast and reliable measurement protocol for Pt, Pd, and Rh measurements are the need of the hour to monitor the magnitude and extent of environ- mental Pt, Pd, and Rh contamination. Quantifcation of PGE mass fractions are most commonly done by inductively coupled plasma mass spectrometers (ICP-MS). However, polyatomic and isobaric interferences (Supplementary Table S1) make these measurements challenging [13]. Spectral interferences can be eliminated using several techniques such as mathematical corrections [14], and various chemical separation techniques namely ion-exchange chromatography [15–19], preliminary acid leaching and co- precipitation with Te or Hg [18,20,21], and NiS fre assay [22]. Chem- ical purifcation techniques can be done both offine and online to minimize spectral interferences, but these techniques are not cost effective, require prolonged sample preparation time with multiple steps. Mathematical correction technique is faster when compared to * Corresponding author at: Department of Earth Sciences, Indian Institute of Technology Kanpur, WLE 201, Kanpur, UP 208016, India. E-mail address: arijeetm@iitk.ac.in (A. Mitra). Contents lists available at ScienceDirect Spectrochimica Acta Part B: Atomic Spectroscopy journal homepage: www.elsevier.com/locate/sab https://doi.org/10.1016/j.sab.2020.106052 Received 28 May 2020; Received in revised form 11 December 2020; Accepted 14 December 2020