Specific analyte-electrolyte additive interaction in transient isotachophoresis-capillary electrophoresis.
While cationic surfactants are usually included in the separation electrolyte to reverse the electroosmotic flow, the presence of the surfactant may also offer a means of capillary electrophoresis (CE) separation selectivity control over the anionic analytes, especially those that are prone to ion-pairing interaction. For one such analyte anion, iodide, the formation of several ion-association/partition products with cetyltrimethylammonium chloride (CTAC) was first discovered when optimizing (decelerating) iodide mobility (in order to achieve effective transient isotachophoretic stacking). At comparatively high concentrations of iodide (> or = 0.01 mM) and the cationic surfactant well above the critical micelle concentration (25 mM), an additional peak due to interactions with the CTAC micelle was recorded, with a UV absorption spectrum fairly different from those of both interacting partners and also the iodide-monomeric surfactant ion pair. Never observed before in normal CE mode, this phenomenon is believed to have occurred due to the enrichment effect of the initial isotachophoresis state.
Hirokawa
Takeshi
T
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan. hiro77@hiroshima-u.ac.jp
Ichihara
Teppei
T
Timerbaev
Andrei R
AR
D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D004573:Electrolytes; D004586:Electrophoresis / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet
D002593:Cetrimonium Compounds; D004573:Electrolytes; D000077286:Cetrimonium