The enantiomeric separation of several basic drugs was investigated using copper(II)–clindamycin as a new chiral selector. The results show that the chiral selector allows high-resolution separation of some racemic basic drugs, including tropicamide, propranolol, sotalol, bisoprolol, epinephrine, esmolol, atenolol, and metoprolol. The enantioselectivity was influenced by parameters such as the type of metal ion, ratio of clindamycin and Cu(II), pH of the background electrolyte, clindamycin concentration, applied voltage, and capillary temperature. The optimal separation conditions were determined to be 20 mM clindamycin/10 mM Cu²⁺, pH 9.06, at 20 kV and 22 °C within 25 min.

Summary

The enantiomeric separation of chiral drugs by capillary electrophoresis (CE) in nonaqueous system has been investigated. Successful separation of bepridil, ondansetron and pinacidil in formamide using β-cyclodextrin as chiral selector were achieved. The addition of triethylamine into the background electrolyte enhanced the enantiomeric discrimination.

Summary

A protocol is described for the spearation of quaternary amidoamines as well as benzalkonium chloride compounds formulated with the same hydrophobic chain. A baseline separation of the twelve homologues studied was achieved in less than 3.5 minutes using a 56 cm of effective capillary length. The carrier electrolyte was 75 mM phosphate, pH=5.2, with acetonitrile (40%v/v) as organic modifier. The applied voltage was 30 kV and the capillary temperature was thermostated to 40°C. Samples were injected hydrodynamically by applying a positive pressure of 50 mbar for 20 s. Organic modifier was also required in the sample solution to disrupt the formation of micelles by the long-chain surfactants. For this reason, the sample and standards were diluted with acetonitrile: water solution (40%v/v) to appropriate concentrations.

Direct capillary zone electrophoretic methods were developed for the separation of the enantiomers of 1-(α-aminoarylmethyl)-2-naphthol and 2-(α-aminoarylmethyl)-1-naphthol analogues. The effects of selector and buffer concentrations, electrolyte pH and applied voltage on the separation efficiency were studied. Variation of the electrophoretic conditions with the application of negative polarity, hydrodynamic injection, an unmodified silica capillary, different buffers and sulfated cyclodextrins and (S,S)-dimethylpyridino-18-crown-6 ether as chiral selectors led to the baseline resolution of all the compounds investigated.

Summary

Robustness testing of capillary electrophoresis methods is an important part of method validation. Appropriate use of experimental designs can be employed in this robustness testing. In this study experimental designs were used in the assessment of a capillary electrophoresis method used to determine drug related impurities. Initially a fractional factorial screening design was used to identify the critical parameters which were found to be pH and voltage. A central composite design was then performed to evaluate the response surfaces for pH and voltage which showed operation at the optimum pH and voltage values.

Summary

Diethylaminoethyl (DEAE) dextran hydrochloride and three kinds of aminoglycosidic antibiotics; fradiomycin sulfate, kanamycin sulfate and streptomycin sulfate, were employed as chiral selectors in capillary electrophoresis, enantiomer separation. These selectors are cationic or basic because of amino functionality and therefore used for enantiomer separation of acidic compounds. To avoid adsorption of the basic or cationic selectors on the capillary inner surface, a coated capillary was employed. Among those tested, enantiomers of binaphthyl compounds and synthetic intermediates of diltiazem analogues were separated. Methanol addition was effective for the improvement of peak shape and resolution.

Summary

The application of capillary electrophoresis (CE) to the separation and determination of the active ingredient, 10-hydroxy-2-decenoic acid, in royal jelly with direct on-column UV detection at 214 nm is described. Using a cathodic injection and anodic detection scheme, 10-hydroxy-2-decenoic acid (10-HDA) was separated and detected in less than 10 min in a fused silica capillary column with a phosphate buffer at pH 7.3 with an applied voltage of 20 KV followed by direct UV detection. The use of cetyltrimethylammonium bromide (CTAB) as electroosmotic flow modifier allows the rapid separation of 10-HDA from other constituents in royal jelly by reversing the direction of electroosmotic flow. The influence of organic solvents in the electrolyte on separation selectivity is also discussed.

Mutations at codons 248 and 249 of p53 gene showed a relatively high incidence in gastric cancer patients. Development of novel methods for the detection of codon mutations is of great importance for gastric cancer research. Studies have showed that the separation matrix can significantly influence the separation efficiency and resolution of small DNA fragments in CE. In order to achieve baseline separation of PCR-amplified products of small DNA fragments from gastric cancer tissue, linear polyacrylamides (LPA I and LPAII) were designed and synthesized in the current study. LPAI and LPAII were used as separation matrixes to separate small size fragments (less than 70 bp) of pBR322/BsuRI DNA Marker and the separation conditions were optimized. Optimum separations were performed at 25 kV in reversed-polarity mode with capillary temperature set at 15 °C. The signal of DNA fragments was detected using laser-induced fluorescence detector, with an argon ion laser as the excitation source that emits at 488 nm. A 520 nm bandpass filter was used as an emission cut-off filter. The resolution of small DNA fragments was higher when LPAI was used as separation matrix compared to LPAII, accompanied with longer migration time. The results indicated that LPAI as separation matrix was more efficient for the separation of small DNA fragments (less than 70 bp) than other LPAs. A rapid and sensitive analysis method for the separation and detection of small DNA fragments (less than 70 bp) was established in this study. The method was successfully applied to detect the mutations at codons 248 and 249 in p53 gene from gastric cancer tissues.

A rapid and practical capillary electrophoresis (CE) method was developed for the determination of 2-methoxycinnamic acid, 4-hydroxyl-3-methoxycinnamic acid, vanillic acid, salicylic acid and 3,4-dihydroxybenzoic acid in tobacco samples. Five phenolic acids were Soxhlet extracted with NaOH solution following solid phase extraction (SPE) clean-up. The CE method was optimized with the running buffer of 25 mmol L⁻¹ sodium borate (pH 9.3), and the applied separation voltage of +25 kV over a capillary of 75 μm i.d. × 375 μm o.d. × 48.5 cm (40 cm to the detector window), which gave a baseline separation of five phenolic acids within about 7 min. Under the detection at 205 nm, the method gave the limits of quantification (S/N = 10) at about 1.6–3.0 μg g⁻¹ for five phenolic acids, whereas the overall recoveries were >80%. The proposed method has been successfully applied to measure five phenolic acids in ten actual tobacco samples, and their contents were obtained and evaluated.