Use of contactless conductivity detection for non-invasive characterisation of monolithic stationary-phase coatings for application in capillary ion chromatography.
A capacitively-coupled contactless conductivity detector (C4D) has been utilised as an on-capillary detector within a capillary ion chromatograph, incorporating a reversed-phase monolithic silica capillary column semi-permanently modified with a suitable ionic surfactant. The monolithic capillary column (150 x 0.1 mm i.d.) was modified using sodium dioctyl sulfosuccinate (DOSS), an anionic surfactant, for the separation of small inorganic and organic cations. With the use of the on-capillary conductivity detector, the longitudinal homogeneity and temporal stability of the coating were investigated. The approach allowed a detailed non-invasive observation of the nature of the ion-exchange coating over time, and an example of an application of the technique to produce a longitudinal stationary-phase charge gradient is shown. An investigation of the basis of the measured on-capillary conductivity was carried out with a counter ion study, clearly showing the on-capillary detection technique could also distinguish between chemical forms of the immobilised ion exchanger. The above method was used to produce a stable and homogeneously-modified monolithic ion-exchange capillary column, for application to the separation of inorganic alkaline earth cations and amino acids.
Gillespie
Eoin
E
National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
Connolly
Damian
D
Macka
Miroslav
M
Nesterenko
Pavel N
PN
Paull
Brett
B
D000596:Amino Acids / Q000032:analysis; D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000379:methods*; D004143:Dioctyl Sulfosuccinic Acid; D004553:Electric Conductivity; D012822:Silicon Dioxide; D013501:Surface-Active Agents
D000596:Amino Acids; D013501:Surface-Active Agents; D004143:Dioctyl Sulfosuccinic Acid; D012822:Silicon Dioxide