HPLC METHOD FOR SEPARATING ENANTIOMERS OF IMIDAZOLE DERIVATIVES - ANTIFUNGAL COMPOUNDS.

The aim of this study was to test separation possibility of enantiomers of nine active substances belonging to imidazole derivatives: bifonazole, butoconazole, econazole, enilconazole, fenticonazole, isoconazole, miconazole, sertaconazole and tioconazole. The study was performed using HPLC method and the CHI- RALCEL OJ column (10 gm; 250 x 4.6 mm), the mobile phase flow rate of 0.8 mL/min and detection at 220 rim. Mobile phases containing hexane and the following modifiers: alcohols (2-propanol, ethanol, methanol) and diethylamine were tested. At first isocratic elution was used but some enantiomers eluted after a long retention time and their peaks were asymmetrical and too wide. Therefore, a gradient elution was developed allow- ing to obtain satisfactory retention times and other parameters of enentioseparation of the compounds.

QUANTITATIVE DETERMINATION OF RESIDUAL MONOMETHYLAMINE CONTENT IN NEBIVOLOL HYDROCHLORIDE BY HPIC WITH SUPPRESSED CONDUCTIVITY DETECTION.

The aim of this paper was to develop a simple analytical method which could be used to determine a synthesis-derived amount of monomethylamine (MMA) residue present in nebivolol hydrochloride. High-performance ion chromatography (HPIC) method with suppressed conductivity detection was used for this purpose. The HPIC analysis was performed with IonPac CS 14 column (250 x 4 mm) containing a macroporous weak cation-exchange stationary phase eluted with 10 mM methanesulfonic acid (MSA). Validation of the method confirmed its selectivity by achieving a satisfactory separation of alkyl- and alkanolamines and metal cations. The method also showed a sufficient precision (RSD < 5.0%) and accuracy (recovery 90-103%). The calibration plot was linear in the range 0.03-2.4 µg/mL of MMA (r² = 0.9997). The calculated limit of quan- tification LOQ was 0.03 µg/mL. Amount of the MMA contained in nebivolol hydrochloride was determined by direct reading from the calibration curve and by the multiple standard additions method. Both methods showed satisfactory precision (RSD < 10.0%) and they can be used to determine the monomethylamine content in the studied active substance.

Purity determination of gynalgin bactericidal tablets with HPLC method.

The study was aimed at developing a simple HPLC method for the determination of the content of impurities in Gynalgin, a two-component preparation. A satisfactory separation was performed on 250 x 4.6 mm Symmetry C8 column in a gradient elution system: mobile phase A--acetonitrile/buffer, pH 5.5 in 10:90, v/v proportion, and mobile phase B--acetonitrile/buffer, pH 5.5 in 75:25 v/v proportion. Two wavelengths: 250 nm and 315 nm were used for detection. Validation confirmed that the method was linear in a required concentration range. The values of correlation coefficients for specific drug substances and the related impurities were as high as 0.999. The results of the purity tests proved that the method was sufficiently selective and precise.

Determination of sodium metabisulfite in parenteral formulations by HPIC with suppressed conductivity detection.

Sulfurous compounds: sodium sulfite Na2SO3 (E 221), sodium bisulfite NaHSO, (E 222), and sodium metabisulfite Na2S2O5 (E 223) are largely used as antioxidants in many pharmaceutical formulations. A method for determination of sodium metabisulfite in parenteral formulations containing tartrate ions was developed. High-performance ion chromatography (HPIC) method with suppressed conductivity detection was used. A satisfactory separation of SO(3)2- and SO(4)2- was achieved by the proposed HPIC method with 15 mM NaHCO3/0.6 mM Na2CO3 mobile phase and columns with various packing materials: methacrylate polymer -Allsep A-2 Anion (100 x 4.6 mm, 7 microm) and styrene-divinylbenzene copolymer - IonPac AS14A (250 x 4.0 mm, 7 microm). Use of the Allsep A-2 Anion column provides separation of SO(3)2-, SO(4)2- and C4H4O(4)2- present in the investigated products. The calibration plot was linear for 8-267.3 microg/mL sulfite (r = 0.99978, n = 6) and for 3-165.9 microg/mL sulfate (r = 0.9998, n = 6). The limit of detection for SO(3)(2-) and SO(4)2-were 3 microg/mL and 1 microg/mL, respectively.

HPLC method for identification and quantification of benzimidazole derivatives in antiparasitic drugs.

The subject of the study was to develop a versatile HPLC system for identification and determination of four benzimidazole derivatives in the antiparasitic drugs. The tests covered: Zentel, Panacur, Vermox tablets and Systamex suspension. A satisfactory separation was obtained using the Nucleosil C8 column in the gradient system composed of mobile phase A: 85% orthophosphoric acid / water / acetonitrile in 0.05:75:25, v/v/v ratio, and mobile phase B: 85% orthophosphoric acid / water / acetonitrile in 0.05:50:50, v/v/v ratio. Both phases were adjusted to pH = 4.5 with 15% sodium hydroxide solution. A detection at 288 nm for oxfendazole and 254 nm for albendazole, fenbendazole and mebendazole was applied. The correlation coefficients in the range 0,9997 - 0,9999 proved that the calibration curves were linear. The method was validated in terms of selectivity, accuracy and precision.

Determination of active substances in binary mixture antiparasitic veterinary formulations by HPLC.

The purpose of the study was to develop a simple, versatile HPLC method for the identification and quantification of praziquantel and ivermectin (in Equimax) or praziquantel and abamectin (in Abamitel Plus). A satisfactory separation was obtained using the Supelcosil LC-ABZ+ column in gradient system with a mobile phase A: acetonitrile / water in 40:60 ratio and phase B: acetonitrile. The UV detection was set at 245 nm. The correlation coefficient values (> or = 0,998) for all active substances confirmed that the calibration curves (peak area vs. concentration) are linear. The results of the quantification and the statistical evaluation confirmed that the method is accurate and precise. It can also be applied to confirm the identity of benzyl alcohol, methyl p-hydroxybenzoate and propyl p-hydroxybenzoate in Abamitel Plus formulation.