Removal of interferences in the speciation of chromium using an octopole reaction system in ion chromatography with inductively coupled plasma mass spectrometry

When inductively coupled plasma mass spectrometry (ICP-MS) is used for the detection of 52Cr (83.8%) species in ion chromatography (IC), interference from polyatomic ions such as 40Ar12C+ and 35Cl16O1H+, often occurs due to their mass at m/z 52. To address the issue, an octopole reaction system (ORS) in ICP-MS, including He and H2 modes, was used to determine whether the background and interference from polyatomic ions could be reduced in the detection of 52Cr. Compared to standard mode, the polyatomic ions were reduced by either He or H2; for example, more than 97 and 98% of 35Cl was removed using a He and H2 tune, respectively. However, the detection sensitivity for 52Cr was decreased, for example, the sensitivity was 27.95 and 67.02% of the standard mode for Cr(EDTA)2−using a He and H2 tune, respectively. The H2 tune is recommended for the detection of 52Cr at a flow rate of 2.0 mL/min with detection limits in the range of 0.2–0.4 μg/L. The developed method was used to measure chromium speciation in waters containing high concentration of chloride.