CE frontal analysis employing contactless conductivity detection for determination of CMCs of non‐UV absorbing charged surfactants

Abstract

Micellar systems composed of surfactants are used extensively in academia and industry for many different applications. In this work a highly versatile CE method for determination of CMCs of charged surfactants has been developed. In the case of positively charged surfactants a coating procedure of the fused-silica capillary was used, whereas negatively charged surfactants were analyzed using uncoated capillaries. The CE method is based on frontal analysis (FA) employing use of contactless conductivity and UV detection. The main advantages of the method are that it can be used for non-UV absorbing surfactants without introducing marker compounds which previously has been found to affect CMCs, requires very limited sample volume and is easily implemented and automated using standard CE equipment. The fact that counterions and different aggregated states are separated allows a detailed characterization of the micelle systems using the developed method. In the case of UV absorbing surfactants similar results were obtained employing contactless conductivity and UV detection. Finally, CMCs obtained using conductometry gave similar results as compared to the developed CE-FA procedure.

Ten years of axial capacitively coupled contactless conductivity detection for CZE – a review

“…Similarly, the p K a value of a functionalized monolithic material was determined using C 4 D 110. Jensen and coworkers have used CE‐C 4 D as a tool to study non‐covalent interactions between small molecules (inorganic and organic cations) and large macromolecules (dextranes) 111 and for the determination of critical micellar concentrations of surfactants 112.…”

Contactless conductivity detector as a tool for improving universality and sensitivity of capillary electrophoresis‐frontal analysis: Proof of concept

“…As it has been demonstrated in the comprehensive review recently published by Nevídalová et al [11], CE-FA has been mainly used in combination with UV-VIS detectors but its use in conjunction with MS [17,31], laserinduced fluorescence [32], and even with C 4 D has also been reported for the non-UV absorbing charged surfactants critical micellar concentration determination [33] and for the interaction study of negatively charged polymer dextran sulfate and a series of inorganic and organic cations [34]. However, it has never been used to characterize protein-drug binding parameters.…”

Sensitivity enhancement of capillary electrophoresis‐frontal analysis‐based method for characterization of drug‐protein interactions using on‐line sample preconcentration

“…As mentioned above the conventional CE-FA methods are mostly performed with UV-VIS detectors [2]. However, the combination of CE-FA with more sensitive (or universal) detectors, such as capacitively coupled contactless conductivity detection [27,28], MS [10,29], or fluorescence [30], has been described as well. The use of on-line preconcentration techniques in ACE has only been reported in combination with partial-filling ACE to characterize the interaction of glycoprotein-derived oligosaccharides with some plant lectins [31].…”