Permethyl monoamino β-cyclodextrin a new chiral selective agent for capillary electrophoresis

The role of cyclodextrins in chiral capillary electrophoresis

The members of the enantiomeric pairs frequently show rather different biological effects, so their chiral selective synthesis, pharmacological studies and analysis are necessary. CE has unique advantages in chiral analysis. The most frequently used chiral selectors are CDs in this field. This paper gives a short view on the advantages on CE in direct chiral separations, emphasizing the role of CDs. The reason for the broad selectivity spectra of CDs is discussed in detail. The physical background of chiral selective separations is briefly shown in CE. Their interaction mechanisms are shortly defined. The general trend of their use is statistically evaluated. Most frequently used CDs and CD derivatives are characterized. Advantages of ionizable CDs and single-isomer derivatives are shown. The general trend of their use is established.

Chiral analysis of pollutants and their metabolites by capillary electromigration methods

Chiral separation of enantiomers is one of the most challenging tasks for any analytical technique including CE. Since the first report in 1985 showing the great possibilities of CE for the separation of chiral compounds, the amount of publications concerning this topic has quickly increased. Although chiral electromigration methods have mainly been used for enantioseparation of drugs and pharmaceuticals, they have also been applied to analyze chiral pollutants. This article intends to provide an updated overview, including works published till January 2005, on the principal applications of CE to the chiral analysis of pollutants and their metabolites, with special emphasis on articles published in the last 10 years. The main advantages and drawbacks regarding the use of CE for chiral separation of pollutants are addressed including some discussion on the foreseen trends of electromigration procedures applied to chiral analysis of contaminants.

Simultaneous HPLC determination of ketoprofen and its degradation products in the presence of preservatives in pharmaceuticals

A novel and quick high-performance liquid chromatography (HPLC) method with UV spectrophotometric detection was developed and validated for the determination of five compounds in topical gel. The described method is suitable for simultaneous determination of active component ketoprofen, two preservatives methylparaben and propylparaben and two degradation products of ketoprofen--3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid--in a topical cream after long-term stability tests using ethylparaben as an internal standard. The chromatographic separation was performed on a 5microm Supelco Discovery C18 column (125mm x 4mm i.d., Sigma-Aldrich); the optimal mobile phase for separation of ketoprofen, methylparaben, propylparaben, degradation products 3-acetylbenzophenone and 2-(3-carboxyphenyl) propionic acid and ethylparaben as internal standard consists of a mixture of acetonitril, water and phosphate buffer pH 3.5 (40:58:2, v/v/v). At a flow rate of 1.0ml min(-1) and detection at 233nm, the total time of analysis was less than 10min. The method was applied for routine analysis (batch analysis and stability tests) of these compounds in topical pharmaceutical product.

Modified field amplification sample injection for micellar electrokinetic chromatography of neutral compounds with amino-substituted cyclodextrin as carrier and 1-adamantanecarboxylate as displacer

A modified field amplification sample injection method was proposed and evaluated by using positively mono charged cyclodextrin (CD) as carrier and 1-adamantanecarboxylate as displacer for on-capillary preconcentration of neutral compounds and improvement of the concentration limit of detection in micellar electrokinetic chromatography. In modified sample injection mode a displacer plug was introduced before sample injection to reduce the length of the concentrated sample zone and increase the peak height by slowing down the forward movement of the neutral sample associated with beta-CD-NH2 and the backward movement of the neutral sample partitioned in the micelles of sodium dodecyl sulfate. Stability of the inclusion complexes formed between the carrier and the solute was found to be an important factor affecting stacking efficiency in both the conventional field amplification sample injection mode and the modified one. However, further enhancement of the stacking efficiency in the modified mode rested on the relative stability of the displacer-carrier complex to that of the solute-carrier complex. Practical limits to the stacking efficiencies in both modes were discussed as well.

Chiral separation of pyrethroic acids with single isomer permethyl monoamino beta-cyclodextrin selector

Enantiomers and diastereomers of chrysanthemic, permethrinic, and deltamethrinic pyrethroic acids were separated from each other, using positively ionizable permethyl monoamino beta-cyclodextrin (PMMAbetaCD). The highest chiral resolution value was 20.0. The optimum conditions of separation were found to be 16 mM PMMAbetaCD concentration and pH 6.5, where analytes and selector were in oppositely ionized states. Selectivity of PMMAbetaCD proved to be the best among the cyclodextrin derivatives studied.