Direct High-performance Liquid-chromatography Resolution On Chiral Columns of Tiaprofenic Acid and Related-compounds In Bulk Powder and Pharmaceutical Formulations

High-performance liquid chromatography (HPLC) was employed for the separation and determination of impurities [5-benzoyl-2-acetylthiophene (BAT), 5-benzoyl-2-ethylthiophene (BET) and (RS)-5-benzoyl-alpha-methyl-3-thiopheneacetic acid (3-isomer of tiaprofenic acid) contained in bulk racemic tiaprofenic acid and pharmaceutical formulations. Chiral columns containing the 3,5-dimethylphenylcarbamate of cellulose and amylose were used. The effect of the organic modifier, 2-propanol, in the mobile phase was studied. The HPLC method gave good performances from qualitative and a quantitative standpoints, allowing the enantiomeric ratios of tiaprofenic acid and its 3-isomer to be determined together with the related impurities BAT and BET

Enantiomeric Separation of Amino-alcohols on Dinitrobenzoyl-diaminocyclohexane Chiral Stationary Phases

A silica-bonded chiral stationary phase, containing the N,N'-3,5-dinitrobenzoyl derivative of 1R,2R-diaminocyclohexane, was used to separate the enantiomers of some amino alcohols with beta-blocking activity after their conversion to oxazolidin-2-ones. The influence of mobile phase composition (mixtures of hexane with dichloromethane, chloroform, dioxane and isopropanol) on the enantioselectivity and efficiency of the column was evaluated. Furthermore, a tandem arrangement of the chiral column and its racemic version was used to resolve all the stereoisomers of one amino alcohol containing two stereogenic centres

Comparative study between the polysaccharidebased Chiralcel OJ and Chiralcel OD CSPs in chromatographic enantioseparation of imidazole analogues of Fluoxetine and Miconazole.

The enantiomeric separation of a series of imidazole analogues of Fluoxetine and Miconazole endowed with potent antifungal activity was performed using cellulose tris(4-methylbenzoate) (Chiralcel OJ) and cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD) as chiral stationary phases. Binary mixtures of n-hexane and alcohol as well as pure alcohols (ethanol or 2-propanol) were used as eluents. The enantiomer elution order was monitored by chiroptical detectors based on on-line optical rotation and circular dichroism measurements. For some of the compounds studied very high enantioseparation factor values (alpha > 7) on Chiralcel OJ CSP were observed. In order to study the chiroptical characteristics of the two most biologically active compounds, chromatographic resolutions were carried out on a semipreparative scale. Assignment of the absolute configuration was empirically established by comparing the CD spectra of the separated enantiomers with those obtained from the enantiomers of Miconazole