Browsing by Author "Onur, Feyyaz"

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Chemometric quantitative analysis of pyridoxine HCl and thiamine HCl in a vitamin combination by principal component analysis, classical least squares, and inverse least squares techniques
(Marcel Dekker Inc, 2001) Baleanu, Dumitru; Baleanu, Dumitru; Onur, Feyyaz; 56389
Three chemometric techniques were described for the analysis of pyridoxine hydrochloride and thiamine hydrochloride within a vitamin combination in the presence of spectral interferences. For these techniques, the training set was prepared by using synthetic mixtures containing two vitamins in multiple possible combinations for the range of 8-40 mu /mL in 0.1 M HCl. The absorbance values for the training set were obtained by direct measurements at 18 wavelengths in the region 222-305 nm for the zero order spectra. The numerical values were calculated by using the 'Maple V' software. Mean recoveries and relative standard deviations for the principal component analysis, classical least squares and inverse least squares techniques were found as 100.7% and 0.95%; 100.5% and 1.38% and, 99.3% and 1.04 for pyridoxine hydrochloride; and 99.7% and 1.03%; 99.1% and 1.05% and, 99.6% and 1.58% for thiamine hydrochloride, respectively. These three chemometric techniques were successfully applied to vitamin tablets marketed in Turkey. The results were compared with each other and good coincidence was observed.
Simultaneous spectrophotometric analysis of codeine phosphate, acetylsalicylic acid, and caffeine in tablets by inverse least-squares and principal component regression techniques
(Taylor&Francis INC, 2002) Baleanu, Dumitru; Baleanu, Dumitru; Onur, Feyyaz; 56389
Inverse least-squares (ILS) and principal component regression (PCR) techniques were proposed for the spectrophotometric simultaneous analysis of ternary mixture containing codeine phosphate, acetylsalicylic acid and caffeine without any pretreatment. A training set of the title drugs was randomly prepared for both techniques. The absorbance values were measured at the 15 points in the wavelength range 220-290 nm for the absorption spectra. The ILS and PCR calibrations were constructed by using their algorithms and they were tested for the synthetic mixtures of three drugs. Means recoveries and relative standard deviations for ILS and PCR were found as 100.2 and 1.23%, 99.5 and 2.10% for codeine phosphate, 100.5 and 1.30%, 100.3 and 1.18% for acetylsalicylic acid and 99.4 and 1.33%, 99.3 and 1.31% for caffeine, respectively. We realised the numerical computations by using the 'Maple V' software. The results were successfully observed by applying the chemometric techniques to the tablets, and a good agreement was found between the obtained values and the indicated quantities of the pharmaceutical formulation marketed in Turkey.
Spectrophotometric determination of acetaminophen and chlorzoxazone in tablets by multivariate calibration techniques
(Chiminform Data S A, 2006) Baleanu, Dumitru; Özdemir, Abdil; Onur, Feyyaz; Baleanu, Dumitru; Aksoy, Halil; Yücesoy, Cem; 6981; 26096; 3512
Three multivariate techniques, Inverse Least Squares (ILS), Principal Component Regression (PCR) and Partial Least Squares (PLS) were applied to the spectrophotometric determination of acetaminophen (AC) and chlorzoxazone (CL) in tablets without prior separation. Stock solutions of acetaminophen and chlorzoxazone were prepared in methanol. Standard solutions were obtained by dilution of stocks with 0.1 M HCl. The multivariate calibrations were built up using training set containing both drugs in different concentration ratios and measuring the absorbances at 14 wavelengths with 5-nm intervals over the wavelength-range of 210-310 nm. Chemometric calculations were performed with MATLAB 7.0 software, The proposed techniques were applied to a commercial formulation, which contains 300 mg AC and 250 mg a(n=10). The results were statistically compared with each other, as well as those obtained by the developed HPLC method.
Spectrophotometric multicomponent analysis of a mixture of metamizol, acetaminophen and caffeine in pharmaceutical formulations by two chemometric techniques
(Pergamon-Elsevier Science LTD, 2001) Baleanu, Dumitru; Baleanu, Dumitru; Onur, Feyyaz; 56389
Inverse least squares (ILS) and factor-based (principal component analysis (PCA)) techniques were proposed for the spectrophotometric multicomponent analysis of a ternary mixture consisting of metamizol, acetaminophen and caffeine, without prior separation. In these chemometric techniques, the measurements of the absorbance values were realized in the spectral range from 225 to 285 nm in the intervals of Delta lambda = 5 nm at the 13 wavelengths in the zero-order spectra of the different ternary mixtures of these active ingredients in 0.1 M HCl. The prepared calibrations of both techniques using the absorbance data and concentration matrix data sets were used to predict the concentration of the unknown concentrations of metamizol acetaminophen and caffeine in their ternary mixture. The 'MAPLE V' software was used for the numerical calculations, Mean recoveries and relative standard deviations for ILS and PCA techniques were found to be 99.8 and 1.68%, 99.9 and 1,66% for caffeine, 99.8 and 1.84%, 100.4 and 2.85% for metamizol, and 99.7 and 1.04%, 99.6 and 1.34/ for acetaminophen, respectively, for the first and second techniques. The techniques were successfully applied to two pharmaceutical formulations marketed in Turkey and results were compared with a new high-performance liquid chromatography method. (C) 2001 Elsevier Science B.V. All rights reserved.