Online isotope dilution and inductively coupled plasma mass spectrometry: from elemental to species quantification

Flow analysis has been utilized for elemental and species quantification by online isotope dilution inductively coupled plasma mass spectrometry (ICP-MS). Online isotope dilution (ID) herein refers to strategies promoting the addition of enriched isotopic solutions to the samples while flowing towards the plasma. Applications of online ID's are commonly performed in aqueous media, however, in some processes the analyte transference to the vapor phase using electrothermal vaporization, vapor generation or laser ablation is also required. Flow diagrams to perform online pre or post-column spiking with the enriched isotope for quantification by ID in speciation analysis by liquid chromatography, gas chromatography or capillary electrophoresis devices coupled to ICP-MS are presented. The main figures of merit and equations applied to elemental and species quantification by ID in flowing schemes are assessed.