ABSTRACT
A simple, rapid, and sensitive method based on gas chromatography with flame ionization detection is described for the determination of finasteride in tablets. The method is based on the derivatization of finasteride with N,O-bis(trimethylsilyl)trifluoroacetamide-1% trimethylchlorosilane at 60 degrees C for 30 min. The method was validated for specificity, linearity, precision, accuracy, robustness, and limit of quantification. The degree of linearity of the calibration curves, the percentage recoveries of finasteride, and the limit of detection (LOD) and limit of quantification (LOQ) for the gas chromatographic method were determined. The assay was linear over the concentration range of 10 to 50 microg ml(-1) (R approximately 0.999). LOQ and LOD (signal/noise ratio = 10) were found to be 10 and 2 microg ml(-1), respectively. The method was found to be simple, specific, precise, accurate, and reproducible. All of the validation parameters were within the acceptance range. The developed method was applied successfully to estimate the amount of finasteride in tablets. The results were compared statistically with those obtained by the official method using t and F tests. There was no significant difference between the two methods with respect to mean values and standard deviations at the 95% confidence level.
Subject(s)
Finasteride/analysis , Chromatography, Gas/methods , Flame Ionization/methods , Molecular Conformation , Reproducibility of Results , Sensitivity and Specificity , TabletsABSTRACT
UV- and second derivative-spectrophotometric and high-performance liquid chromatographic methods for the determination of valsartan in pharmaceutical formulation have been developed. For the first method, UV-spectrophotometry, standard solutions were measured at 205.6 nm. The linearity changes were found to be 2.0-10.0 microg ml(-1) in ethanol and the regression equation was A=1.05 x 10(-1)C+4.26 x 10(-2) (r=0.9997). For the second method, the distances between two extremum values (peak-to-peak amplitudes), 221.6 and 231.2 nm were measured in the second order derivative-spectra of standard solutions. Calibration curves were constructed by plotting d(2)A/dlambda(2) values against concentrations, 0.5-4.0 microg ml(-1) of valsartan standards in ethanol. Regression equation of linear calibration graph was calculated as D=2.9 x 10(-2)C-2.37 x 10(-3) (r=0.9996). The third method was based on high-performance liquid chromatography on C18 column using acetonitrile, phosphate buffer as a mobile phase and losartan as internal standard. Detection was carried out at 265 nm with a UV-detector. The assay was linear over the concentration range at 1.0-5.0 microg ml(-1) and regression equation was found to be A=2.74 x 10(-1)C+2.06 x 10(-2) (r=0.9991). Commercial capsules containing 160 mg valsartan were analysed by the developed methods and the results obtained were compared statistically at 95% confidence level.
Subject(s)
Tetrazoles/analysis , Valine/analogs & derivatives , Valine/analysis , Chemistry, Pharmaceutical , Chromatography, High Pressure Liquid/methods , Chromatography, High Pressure Liquid/statistics & numerical data , Pharmaceutical Preparations/analysis , Pharmaceutical Preparations/chemistry , Spectrophotometry, Ultraviolet/methods , Spectrophotometry, Ultraviolet/statistics & numerical data , Tetrazoles/chemistry , Valine/chemistry , ValsartanABSTRACT
Dracunculus vulgaris Schott is only one taxon of the genus Dracunculus (Araceae) in Turkey. The tubers and the fruits with the seeds of D. vulgaris have long been in use for the treatment of rheumatism and hemorrhoids, respectively. The fatty acid composition of D. vulgaris seeds have been analyzed as their methyl esters by GC and GC-mass spectrometry. C16:0, C16:1n-7, C18:1n-9, C18:1n-7 (cis -vaccenic acid), C18:2n-6 and 13-phenyl tridecanoic acids were found to be the main components in the seed oil.
