HILICpak VN-50 4D, a hydrophilic interaction chromatography (HILIC) column modified with diol functional group was coupled with an ICPMS for the separation analysis of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). In this application, the eluent used has a high proportion of aqueous solution containing 2,6-pyridinedicarboxylic acid (PDCA), also known as dipicolinic acid. The presence of PDCA in the eluent leads Cr(III) to form a stable (Cr(III)-PDCA) complex. The chromatogram below compares the elution profiles with different acetonitrile (ACN) concentrations, ranging from 2 % to 4 %. It demonstrates that Cr(VI) elutes before Cr(III)-PDCA under these conditions (The upper limit of ACN was set at 4 %, as higher ACN concentrations lead to decreased sensitivity). Although simultaneous separation of Cr(VI) and Cr(III)-PDCA is achievable under all eluent conditions, increased ACN concentration promoted earlier elution of Cr(III)-PDCA and also improved their peak shapes. Therefore, 4 % ACN is an optimal concentration for this analysis. In chromium analysis using ICPMS, interference from chloride ions is a concern. The ability to separate chloride ions from chromium prior to introduction into the ICP-MS is crucial for minimizing its impact on the quantification.
*The HPLC system used in this analysis is biocompatible, and the housing material for VN-50 4D is PEEK.

Sample: 100 μL
25 μg L^-1 Cr(Ⅵ)-Cr(Ⅲ)PDCA solution and 0.001 mol L^-1 HCl

1. light grey:2 % ACN
2. grey:3 % ACN
3. black:4 % ACN

Data Provided by Prof. Masaharu Tanimizu, Department of Applied Chemistry for Environment, School of Science and Technology, Kwansei Gakuin University

References:
Ito, A., Morishita, Y., Morimoto, T., Tanimizu, M. Rapid determination of chromium species in environmental waters using a diol-bonded polymer-stationary column under water-rich conditions coupled with ICPMS. ANAL. SCI. (2024). https://doi.org/10.1007/s44211-023-00475-6