Determination of pharmaceutically related compounds by suppressed ion chromatography: II. Interactions of analytes with the suppressor
Karu, N and Dicinoski, GW and Hanna-Brown, M and Haddad, PR, Determination of pharmaceutically related compounds by suppressed ion chromatography: II. Interactions of analytes with the suppressor, Journal of Chromatography A, 1224, (1) pp. 35-42. ISSN 0021-9673 (2012) [Refereed Article]
For the hyphenation of ion chromatography to nebulising detectors or mass spectrometry, suppression of the non-volatile ionic eluent to water is a required step. However, suppression of weakly acidic or weakly basic organic analytes can potentially lead to losses of analytes during suppression resulting
from precipitation, hydrophobic adsorption onto the suppressor, or permeation of the analyte through the suppressor membranes. This study investigates the interactions between the suppressor and weak organic acid analytes, including pharmaceutically related compounds, for eluents containing organic solvent.
Correlations were observed between analyte recovery rates after electrolytic suppression and the eluent composition, the suppression conditions, and the physico-chemical properties of the analytes. These results suggest that hydrophobic adsorption interactions occur in the electrolytic suppressor and
that these interactions are ameliorated by the addition to the eluent of high levels of organic solvents, especially acetonitrile. Use of eluents containing 80% acetonitrile resulted in very low losses of analyte during suppression. Recovery experiments conducted in various compartments of the electrolytic suppressor showed that some analytes permeated through the suppressor membrane into the regenerant chambers, but this could be prevented by adding organic solvent to the regenerant solution. It was also noted that analyte losses increased with ageing of the electrolytic suppressors. Chemical suppression
avoids some of the analyte losses observed with an electrolytic suppressor, but when used under the correct conditions, electrolytic suppressors gave close to equivalent performance to chemical suppressors.
suppressors, ion chromatography, organic acid analytes, analyte loss during suppression