Anion analysis using capillary ion analysis: The chemistry and performance of chromate based electrolyted
Abstract Capillary Ion Analysis (CIA) is a free zone capillary
electrophoresis technique designed for the analysis of inorganic and
organic anions and cations in aqueous matrices. It also incorporates
the use of capillary electrophoresis specific data processing to
account for non-symmetrical peak shapes and quantitation dependent upon
migration time. For inorganic and organic anion analysis, a chromate
based electrolyte is primarily used for separation and detection. In
the 5 years since its commercial introduction, the data processing has
evolved to differentiate capillary electrophoresis data processing from
chromatography data processing. Now, the initial chromate based
electrolyte has been reformulated, based upon observed performance with
real samples, to optimize anion selectivity and electrolyte mobility.
This electrolyte reformulation aids in analyte qualitative
identification when changes in field strength and EOF are observed.
This presentation will overview CIA performance of an evolved chromate
electrolyte formulation that gives improved migration time stability
with respect to analyte concentration, and peak shapes that allow the
low ppb detection of Br, NO2, and NO3 in the presence of high
concentrations of Cl and SO4. The variables of chromate concentration,
osmotic flow modifier cocentration, pH, choice of buffering agents, and
their effect on mobility will be discussed.