Hexadecyltrimethylammonium chloride phase

Mullins and Kirkbright (38) reported separation of the UV absorbing anions iodate, nitrite, bromide, nitrate and iodide using a micellar mobile phase containing hexadecyltrimethylammonium chloride above its CMC. Figure 2 illustrates this separation with two different concentrations of micellar reagent. Increasing the concentration of hexadecyltrimethylammonium chloride decreases the retention time (38) on the column. 

The decrease in retention of the anions as the concentration of hexadecyltrimethylammonium chloride is increased (Figure 2) can be attributed to anion interaction with micelles in the mobile phase. The retention time of the selected anions can be reduced by increasing the concentration of the micellar reagent (Figure 2(a),... 

The retention of the anions on a loaded octadecyl-bonded silica column in the presence of hexadecyltrimethylammonium chloride micellar mobile phase follows the order... 

This order is similar to the anion selectivity order found on a typical strongly basic anion exchanger. Figure 2(b) illustrates a separation of five inorganic anions with a 1.36 x 10 1M hexadecyltrimethylammonium chloride micellar mobile phase. No buffer salts or organic modifier were used in order to accomplish this separation. 

The above results show that conventional HPLC can be used with UV detection for the determination of inorganic anions, namely 103, N02-, Br-, N03 and I" with a cationic micellar mobile phase. One of the attractive features of this procedure is the ability to control retention by control of the concentration of aqueous micellar hexadecyltrimethylammonium chloride rather than by the use of organic modifiers. 

Figure 2. (b) conditions as in (a) but mobile phase. 5 x 10"Vl hexadecyltrimethylammonium chloride. "Reproduced with permission from Ref. 38. Copyright 1984, Royal Society of Chemistry, London". ... 

In addition, one-phase smfactant-assisted chemical method has been utilized to synthesize PANI nanofiber, which was doped with CSA and 2-acrylamido-2-methyl-l-propanesulfonic acid, in large quantities [291]. A chemical oxidative polymerization of aniline has been carried out using ammonium peroxydisulfate as an oxidizing agent in the presence of nonionic surfactant. A precipitate of doped emeraldine salt is composed of PANI nanofiber, which has the diameter of 30-50 nm and exhibits the conductivity of 1 -5 S cm at RT. Another piece of research has been done through chemical oxidation polymerization of aniline in a surfactant gel, which was formed by a mixture of hexadecyltrimethylammonium chloride, acetic acid, anihne, and water at - 7 °C [292]. The dendritic PANI nanofiber has the diameter of 60-90 nm and the length of 1 -2 jim. Extended works have been performed by the electrospinning method [293]. It should be taken into account that PANI-CSA fiber shape could be influenced by the synthetic variables such as solvent, surface tension, viscosity, and solution conductivity. 

CE CGE CHOL CIP CPG CTAB CZE dA, dG, dC DBU DEAE DMF DMT DNP DOPE DOTMA EDTA EM EOF ESI-MS Fmoc FPE ICAM-1 Capillary electrophoresis Capillary gel electrophoresis Cholesterol Cahn-Ingold-Prelog nomenclature system for absolute configuration Controlled pore glass Hexadecyltrimethylammonium bromide Capillary zone electrophoresis Deoxyadenosine, deoxyguanosine, deoxycytosine l,8-Diazabicyc o[5.4.0]undec-7-en Diethylaminoethyl- Dimethylformamide Bis(4-methoxyphenyl)phenylmethyl-, (syn. Dimethoxytrityl-) 2,4-DinitrophenyI- Dioleylphosphatidylethanolamine N-[l-(2,3-dioleyloxy)propyl]-N, N, N-trimethylammonium chloride Ethylenediamine tetra-acetic acid Electrophoretic mobility Electro-osmotic flow Electrospray ionization mass spectrometry 9-Fluorenylmethoxycarbonyl-Fluid phase endocytosis Intracellular Adhesion Molecule-1... 

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