Chromium speciation at trace level in potable water using hyphenated ion exchange chromatography and inductively coupled plasma mass spectrometry with collision/reaction interface

Abstract

A simple method is described for chromium speciation at sub-µg L⁻¹ level in potable water samples using hyphenated ion exchange chromatography (IEC) and inductively coupled plasma mass spectrometry (ICP-MS) with collision/reaction interface (CRI). The redox pair of chromium species Cr(VI) and Cr(III) was separated on an IonPac AG-7 guard column within 7.5 minutes using gradient elution with 0.1 M ammonium nitrate and 0.8 M nitric acid as the mobile phases. Hydrogen CRI gas was useful to eliminate chlorine-based and carbon-based polyatomic interferences. Water samples were analyzed directly, without any pretreatment, to preserve the original Cr speciation. The accuracy of the proposed method was verified using a river water certified reference material, SLRS-2, through good agreement with the certified values. Limits of detection of 0.02 µg L⁻¹ and 0.04 µg L⁻¹ for Cr(VI) and Cr(III), respectively, were obtained.