Laboratory Experiment Cite This: J. Chem. Educ. XXXX, XXX, XXX−XXX
pubs.acs.org/jchemeduc
Using Ion−Molecule Reactions To Overcome Spectral Interferences in ICP-MS: A Guided Inquiry Approach for Upper-Level Undergraduate and Graduate Students Karla Newman* Water Quality Centre, Trent University, Peterborough, Ontario K9L 0G2, Canada S Supporting Information *
ABSTRACT: Almost all commercial quadrupole ICP-MS instruments use collision/reaction cells to either attenuate spectral interferences or shift the analyte of interest to an interference-free m/z (e.g., by O addition). A laboratory practical was developed to introduce the students to the basic operating principles of ICP-MS using a hands-on approach, with an emphasis on practical strategies for the effective use of reaction cells in ICP-MS. Vanadium, and the ClO+ diatomic interference formed in HCl matrixes, was used as an illustrative example, which enabled students to explore charge transfer, clustering, condensation, and oxygen atom addition reactions of a single analyte, and evaluate the most effective approach for the chemical resolution of V+ and ClO+ ions. This laboratory practical provided graduate students with a basic skill set to support the effective use of ICP-MS with reaction cell technology in their research projects. KEYWORDS: Upper-Division Undergraduate, Graduate Education/Research, Analytical Chemistry, Physical Chemistry, Hands-On Learning/Manipulatives, Inquiry-Based/Discovery Learning, Atomic Spectroscopy, Instrumental Methods, Mass Spectrometry
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INTRODUCTION In the past 20 years, inductively coupled plasma mass spectrometry (ICP-MS) has become the workhorse of elemental analysis. The high sensitivity, element specificity, and dynamic range of the technique, together with the capacity for high sample throughput and versatility in terms of sample introduction systems, make ICP-MS an invaluable tool in modern inorganic mass spectrometry.1 Commercial ICP-MS instruments are very user-friendly, so that even inexperienced users can measure trace element concentrations in prepared samples after only a few hours of training. However, the accurate quantification of elements at very low concentrations (sub-ppt) or in complex matrixes (e.g., industrial effluents, biological tissues, seawater) is more challenging. Particularly for low mass elements (
