Comparison of standard and reaction cell inductively coupled plasma mass spectrometry in the determination of chromium and selenium species by HPLC–ICP–MS

Elemental speciation is becoming a common analytical procedure for geochemical investigations. The various redox species of environmentally relevant metals can have vastly different biogeochemical properties, including sorption, solubility, bioavailability, and toxicity. The use of high performance liquid chromatography (HPLC) coupled to elemental specific detectors, such as inductively coupled plasma mass spectrometry (ICP–MS), has become one of the most important speciation methods employed. This is due to the separation versatility of HPLC and the sensitive and selective detection capabilities of ICP–MS. The current study compares standard mode ICP–MS to recently developed reaction cell (RC) ICP–MS, which has the ability to remove or reduce many common polyatomic interferences that can limit the ability of ICP–MS to quantitate certain analytes in complex matrices. Determination of chromium and selenium redox species is achieved using ion-exchange chromatography with elemental detection by standard and RC–ICP–MS, using various chromium and selenium isotopes. In this study, method performance and detection limits for the various permutations of the method (isotope monitored or ICP–MS detection mode) were found to be comparable and generally less than 1 μg L−1. The method was tested on synthetic laboratory samples, surface water, groundwater, and municipal tap water matrices.