betadex and tetrabutylammonium

In recent years increasing interest was drawn towards ionic liquids in analytical separation science, such as capillary electrophoresis. Ionic liquids combining tetrabutylammonium cations with chiral amino acid based anions were prepared and investigated as capillary electrophoresis background electrolyte additives for the enantioseparation of ephedrine, pseudoephedrine, and methylephedrine isomers. For the optimization of buffer pH and ionic liquid concentration a design of experiments approach was performed. The best results for the separation of all enantiomers were achieved using 125mmol/L tetrabutylammonium l-argininate in a 75mmol/L phosphate buffer pH 1.5 containing 30mmol/L β-cyclodextrin.

Topics: Amino Acids; beta-Cyclodextrins; Electrophoresis, Capillary; Hydrogen-Ion Concentration; Ionic Liquids; Phenethylamines; Quaternary Ammonium Compounds

Cellulose dissolution is a challenging process which is typically very sensitive to the solvent characteristics such as pH, temperature or presence of additives. Regarding the later aspect, it is here reported the interaction between α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) with the tetrabutylammonium cation (TBA(+)) by (1)H NMR titration experiments. The analysis by the continuous variation method suggests the formation of 1:1 CD:TBA(+) complexes. However, the computed apparent association constants reveal that the interaction of TBA(+) with the β-CD (K=1580M(-1)) is unexpectedly stronger than with α-CD (K=106M(-1)). In both CD cases, the formation of CD:TBA(+) complexes decrease the dissolution efficiency of the solvent and this has been rationalized as an effective decrease in the concentration of the amphiphilic cation and concomitant weakening of the hydrophobic interactions in solution influencing the overall performance of the solvent. Additionally, the data also supports the fact that amphiphilic species in solution are beneficial for the enhancement of cellulose solubility.

Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cellulose; Quaternary Ammonium Compounds

The non-polar internal cavity of β-cyclodextrin (β-CD) has been exploited for the entrapment of the hydrophobic tails of two water insoluble quaternary ammonium permanganates (QAPs): cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), for solubilization in aqueous medium. The solubilization and organizational behavior of the QAPs in aqueous β-CD solution have been determined from the comparison of their rates of self-oxidation in presence and in absence of β-CD. Effect of QAP concentration on their observed rate constants (k(obs)) at a fixed β-CD concentration, phase solubility analysis in varying β-CD concentration, impact of quaternary ammonium bromides (QABs) on the kobs values of CTAP and TBAP at fixed QAP and β-CD concentrations, and the temperature effect have been reported. A scheme to explain the solvation of QAPs in aqueous β-CD has been proposed based on dynamic light scattering (DLS) analysis of the samples.

Topics: beta-Cyclodextrins; Cetrimonium; Cetrimonium Compounds; Hydrophobic and Hydrophilic Interactions; Manganese Compounds; Oxides; Quaternary Ammonium Compounds; Solubility; Water

Approaches to improve resolution in chiral separation of several basic pharmaceutical compounds by capillary electrophoresis (CE) via a cyclodextrin (CD) inclusion complexation are described. Tetraalkylammonium reagents, including long-chain cationic surfactants and short-chain alkylammonium hydroxides, are examined for controlling the electroosmotic flow in order to improve resolution of the cationic enantiomers. In this regard, short-chain tetraalkylammonium cations (such as tetrabutylammonium and tetramethylammonium are more effective. First, the short-chain tetraalkylammonium cations can be used at much higher concentrations than the long-chain cationic surfactants, which form micelles in the few millimolar concentration range. As a result, a better capillary wall coverage is provided with the short-chain reagents, which leads to reduction or reversal of the direction of the electroosmotic flow at the acidic pH 2.5. Second, the short-chain tetraalkylammonium cations are relatively less hydrophobic and less likely to occupy the hydrophobic cavity of beta-CD than the long-chain cationic surfactants, leaving the enantioselective interaction sites more available for the analytes. The presence of these tetraalkylammonium cations was essential in many chiral separations that were reportedly not achieved by using the buffer electrolytes containing only the beta-CD as a chiral selector. In addition, a mechanism of chiral recognition by beta-CD for a group of stereoisomers is discussed.

Topics: beta-Cyclodextrins; Chemistry Techniques, Analytical; Cyclodextrins; Electrophoresis; Hydrogen-Ion Concentration; Indicators and Reagents; Quaternary Ammonium Compounds; Software; Stereoisomerism; Surface-Active Agents

Capillary electrophoresis with on-column UV detection at 214 nm was used to separate a group of nine antihistamines. All these compounds were satisfactorily separated within ca. 6 min using a mixed carrier system containing sodium dodecyl sulphate with beta-cyclodextrin and tetrabutylammonium hydrogensulphate as modifiers. The application of the method to the determination of the amount of antihistamines present in commercial pharmaceutical samples was demonstrated. In addition, the migration behaviour of the antihistamines in the mixed carrier system was examined.

Topics: beta-Cyclodextrins; Capillary Action; Cyclodextrins; Electrophoresis; Histamine H1 Antagonists; Quaternary Ammonium Compounds