LC method for the analysis of Oxiconazole in pharmaceutical formulations.
A LC method has been developed for the quantitative determination of Oxiconazole (Ox) in bulk form, lotion and cream pharmaceutical formulations. The method validation yielded good results including the range, linearity, precision, accuracy, recovery, specificity, robustness, limit of quantitation and limit of detection. The LC separation was carried by reversed phase chromatography using a LiChrocart C(8) column (125 mm x 4.0 mm i.d., 5 microm particle size). The mobile phase was composed of methanol-0.02 M ammonium acetate buffer (85:15 v/v), pumped isocratically at flow rate 1 ml min(-1). The detection was carried out on UV detector at 254 nm. The calibration curve for Ox was linear from 40.0-140.0 microg ml(-1) range. The precision of this method, calculated as the relative standard deviation (R.S.D.) was 1.57% for lotion and 0.71% for cream. The R.S.D. values for intra- and inter-day precision studies were 0.57 and 1.34%, respectively. The recovery of the drug ranged between 98.84-102.2% (lotion) and 100.54-101.59% (cream). The stability indicating capability of the assays was proved using forced degradation. Chromatograms showed Ox well resolved from the degradation product.
Peculiarities of an imidazole derivative retention mechanism in reversed-phase liquid chromatography: β-cyclodextrin concentration and temperature considerations
Abstract The retention mechanism of a series of imidazole derivatives in reversed-phase liquid chromatography (RPLC) was investigated over a range of column temperatures and β-cyclodextrin concentrations. The changes in van't Hoff plots as a function of the β-cyclodextrin concentration were examined. Enthalpy, entropy and the Gibbs free energy were determined for the two physicochemical processes: (i) the solute transfer from the mobile to the stationary phases, (ii) the solute complexation by β-cyclodextrin. These thermodynamic data showed that the solute retention mechanism was dependent on the β-cyclodextrin concentration in the mobile phase. Enthalpy–entropy compensation revealed that the main parameter determining retention increased as follow: β-cyclodextrin⇄solute complexation>RP18 stationary phase⇄solute interaction. This fact confirms that the main parameter determining retention in RPLC is the distribution of the solute molecule in the mobile phase, whereas the interactions with the stationary phase play a minor role.
Benign approaches for the synthesis of bis-imine Schiff bases
Pure bis-imine Schiff bases are readily accessible in high yield, typically >95%, when aliphatic diamine/aldehyde condensation reactions are carried out under solvent-free conditions or in poly(propyleneglycol) (PPG) as a recyclable reaction medium, with negligible waste.