betadex and formic-acid

Various amino acids, dipeptides and their isomers were (enantio)separated using sulfobutylether-β-cyclodextrin as a chiral selector. Two different approaches were employed: first, dynamic coating of sulfobutylether-β-cyclodextrin onto a strong anion-exchange stationary phase and, second, use of sulfobutylether-β-cyclodextrin as a mobile phase additive in a separation system with a C18 column. Measurements were carried out using RP-HPLC and hydrophilic interaction liquid chromatography. Mobile phases composed of organic modifier (methanol) and four different aqueous parts: (i) deionized water, (ii) an aqueous solution of formic acid (pH 2.1), (iii) ammonium acetate buffer (pH 4.7), and (iv) ammonium acetate buffer (pH 8.8) in various volume ratios. Under these separation conditions, out of 23 chiral analytes, 9 were baseline enantio-resolved and 7 were partially separated. Of 9 mixtures of dipeptide isomers, 8 were baseline-separated. Sulfobutylether-β-cyclodextrin proved to be suitable for the separation of chiral and also achiral analytes. The use of sulfobutylether-β-cyclodextrin as a dynamic coating agent or as a mobile phase additive depends on the particular chromatographic system and analytes of interest.

Topics: Acetates; Amino Acids; beta-Cyclodextrins; Buffers; Chromatography, High Pressure Liquid; Dipeptides; Formates; Indicators and Reagents; Stereoisomerism; Water

A chiral capillary electrophoretic method with nearly full pH window was explored for the separation and determination of dl-penicillamine. A facile one-pot labeling technique was coupled in the method for introduction of chromophore and charge groups onto the analytes to facilitate the electromigration and sensitive detection. By using simply a cost-effective neutral β-cyclodextrin as chiral selector, baseline separation of the dl-penicillamine was achieved from pH 2.0 to over pH 10. Quantification of standard d- and l-penicillamines was demonstrated by taking pH 4.5, 7.4, and 9.7 as the representatives of acidic, neutral, and basic conditions. The working curves were constructed between peak area and concentration, having linear ranges of 8.56-8.56 × 10(2) μg/mL for pH 4.5 and 8.56-1.71 × 10(3) μg/mL for pH 7.4 and 9.7, with correlation coefficients all better than 0.999. The limit of detection (S/N = 3) was 2.58 μg/mL in acidic and neutral conditions or 1.41 μg/mL in basic condition. The method was further validated by assaying the commercial penicillamine tablets, applicable to quantification of the effective enantiomer and the trace impurity of l-penicillamine at a content of down to 0.2, 0.6, and 2.0% for pH 9.7, 4.5, and 7.4, respectively. The recovery determined by spiking technique was in a range from 93.1 to 105 %. The method is easily extendable to the analysis of other chiral amines or amino acids.

Topics: Acetic Acid; beta-Cyclodextrins; Electrophoresis, Capillary; Formates; Hydrogen-Ion Concentration; Limit of Detection; Penicillamine; Phosphates; Reproducibility of Results; Stereoisomerism; Tablets

Capillary electrophoresis (CE) coupled to tandem mass spectrometry was applied to the chiral separation of baclofen using sulfobutylether-beta-cyclodextrin chiral selector in partial filling counter current mode. On-line UV detection was simultaneously used. Method optimization was performed by studying the effect of cyclodextrin and BGE concentration as well as sheath liquid composition on analyte migration time and enantiomeric resolution. The cyclodextrin showed stereoselective complexation towards baclofen enantiomers, allowing chiral resolution at low concentration. The CE capillary protrusion from the ESI needle relevantly affected the chiral resolution and the analyte migration time. Complete enantiomeric separation was obtained by using 0.25 M formic acid BGE containing 1.75 mM of chiral selector and water/methanol (30:70, v/v) 3% formic acid as sheath liquid. The method exhibited a LOD of 0.1 microg/mL (racemic concentration) in MS3 product ion scan mode of detection and was applied to the analysis of racemic baclofen in pharmaceutical formulations.

Topics: Baclofen; beta-Cyclodextrins; Electrophoresis, Capillary; Formates; Pharmaceutical Preparations; Sensitivity and Specificity; Stereoisomerism; Tandem Mass Spectrometry