Biomedical subjects

Erdal Dinç

Publications and source records attributed to Erdal Dinç.

At least 19 recordsLinked to original sources

PubMed2006

Chemometric determination of naproxen sodium and pseudoephedrine hydrochloride in tablets by HPLC.

A new chemometric determination by high-performance liquid chromatography (HPLC) with photodiode array (PDA) detection was implemented for the simultaneous determination of naproxen sodium and pseudoephedrine hydrochloride in tablets. Three chemometric calibration techniques, classical least squares (CLS), principle component regression (PCR) and partial least squares (PLS) were applied to the peak area at multiwavelength PDA detector responses. The combinations of HPLC with chemometric calibration techniques were called HPLC-CLS, HPLC-PCR and HPLC-PLS. For comparison purposes the HPLC method called the classic HPLC method was used to confirm the results obtained from combined HPLC-chemometric calibration techniques. A good chromatographic separation between two drugs with losartan potassium as an internal standard was achieved using a Waters Symmetry C18 Column 5 microm 4.6+/-250 mm and a mobile phase containing 0.2 M acetate buffer and acetonitrile (v/v, 40:60). The multiwavelength PDA detection was measured at five different wavelengths. The chromatograms were recorded as a training set in the mobile phase. Three HPLC-chemometric calibrations and the classic-HPLC method were used to test the synthetic mixtures of naproxen sodium and pseudoephedrine hydrochloride in the presence of the internal standard. The HPLC-chemometric approaches were applied to real samples containing drugs of interest. The experimental results obtained from HPLC-chemometric calibrations were compared with those obtained by a classic HPLC method.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

A new fractional wavelet approach for the simultaneous determination of ampicillin sodium and sulbactam sodium in a binary mixture.

A new application of the fractional wavelet transform (FWT) was proposed for the simultaneous determination of ampicillin (AP) and sulbactam (SB) in a pharmaceutical combination for injection. FWT approach is a new powerful tool for removing noise and irrelevant information from the absorption spectra. Cardinal information having higher peak amplitude, eliminated noise, sharp peaks with shrinking width of spectral range was obtained by the application of FWT procedure to the original absorption spectra. In this paper, FWT approach was subjected to the data vector of the UV-signals obtained from AP and SB in the wavelength range of 211.5-313.8 nm. Derivative transform was applied to the original absorption signal together with its FWT generalization. The calibration graphs for AP and SB were obtained by measuring the FWT and usual derivative amplitudes at zero-crossing points. The method validation was carried out by using the synthetic mixture analysis. Our proposed FWT approach was compared with the usual derivative spectrophotometry and chemometric methods (CLS, PCR and PLS) and a good agreement was reported.

Absorption↗

PubMed2005

Mathematical algorithms applied to the multi-linear regression functions for the multicomponent determination of pharmaceutical dosage form containing three-component mixtures.

In the presence of closely overlapping spectra, the quantitative multiresolution of ternary mixtures of three active compounds paracetamol (PAR), caffeine (CAF) and acetylsalycilic acid (ASP) in tablets, without using pretreatment such as separation step and graphical procedure of spectra was accomplished by the multivariate spectral calibration models, tri-linear regression calibration (TLRC), multi-linear regression calibration (MLRC) and Cramer's rule solution (CRS) of three linear equation functions in the matrix form. In the first two models, TLRC and MLRC are based on the use of the linear regression functions at selected wavelength sets in the spectral region of 210-300 nm. In the case of CRS model, A1(1) (1%, 1 cm) were used to obtain three linear equation functions and this linear equation system was resolved by the Cramer's rule for the prediction of PAR, CAF and ASP in samples. In the TLRC and CRS models, the selection of the appropriate wavelength set was performed by the Kaiser's technique. The algorithms of these mathematical calibration models were briefly described. The validation of TLRC, MLRC and CRS models was carried out by analyzing various synthetic ternary mixtures and by using the standard addition technique. These three calibration approaches were applied to the analysis of the real pharmaceutical tablets containing PAR, CAF and ASP. The obtained results were statistically compared with each other by using experimental and statistical tests. In the comparison of TLRC and MLRC models to the classical approach, CRS technique, the successful assay results were observed for the quantitative multiresolution of ternary mixture of the subject active compounds.

Acetaminophen↗

PubMed2004

Comparative study of the continuous wavelet transform, derivative and partial least squares methods applied to the overlapping spectra for the simultaneous quantitative resolution of ascorbic acid and acetylsalicylic acid in effervescent tablets.

The simultaneous spectrophotometric determination of ascorbic acid (AA) and acetylsalicylic acid (ASA) in effervescent tablets in the presence of the overlapping spectra was accomplished by the continuous wavelet transform (CWT), derivative spectrophotometry (DS) and partial least squares (PLS) approaches without using any chemical pre-treatment. CWT and DS calibration equations for AA and ASA were obtained by measuring the CWT and DS amplitudes corresponding to zero-crossing points of spectra obtained by plotting continuous wavelet coefficients and first-derivative absorbance values versus the wavelengths, respectively. The PLS calibration was constructed by using the concentration set and its full absorbance data consisting of 850 points from 220 to 305 nm in the range of 210-310 nm. These three methods were tested by analyzing the synthetic mixtures of the above drugs and they were applied to the real samples containing two commercial pharmaceutical preparations of subjected drugs. A comparative study was carried out by using the experimental results obtained from three analytical methodologies and precise and accurate results were obtained.

Ascorbic Acid↗

PubMed2004

Simultaneous spectrophotometric determination of pseudoephedrine hydrochloride and ibuprofen in a pharmaceutical preparation using ratio spectra derivative spectrophotometry and multivariate calibration techniques.

Spectrophotometric methods are described for the simultaneous determination of pseudoephedrine hydrochloride and ibuprofen in their combination. The obtained data were evaluated by using five different methods. In the first method, ratio spectra derivative spectrophotometry, analytical signals were measured at the wavelengths corresponding to either maximums and minimums for both drugs in the first derivative spectra of the ratio spectra obtained by using each other spectra as divisor in their solution in 0.1 M HCl. In the other four spectrophotometric methods using chemometric techniques, classical least-squares, inverse least-squares, principal component regression and partial least-squares (PLS), the concentration data matrix were prepared by using the synthetic mixtures containing these drugs in methanol:0.1 M HCl (3:1). The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbances in the range 240-285 nm in the intervals with deltalambda = 2.5 nm at 18 wavelengths in their zero-order spectra, then, calibration or regression was obtained by using the absorbance data matrix and concentration data matrix for the prediction of the unknown concentrations of pseudoephedrine hydrochloride and ibuprofen in their mixture. The procedures did not require any separation step. The linear range was found to be 300-1300 microg/ml for ibuprofen and 100-1300 microg/ml for pseudoephedrine hydrochloride in all five methods. The accuracy and the precision of the methods have been determined and they have been validated by analyzing synthetic mixtures. The five methods were successfully applied to tablets and the results were compared with each other.

Calibration↗

PubMed2004

Wavelet analysis for the multicomponent determination in a binary mixture of caffeine and propyphenazone in tablets.

An approach based on both discrete and continuous wavelet analysis followed by a zero-crossing technique was developed. We applied this approach to obtain a high resolution in the binary mixture of caffeine (CA) and propyphenazone (PR) in the presence of their overlapping signals in the working length. The optimization of the wavelet families was accomplished for this mixture. The de-noise procedure was carried out by using 4-level Haar discrete wavelet transform and the resulted de-noised signal was investigated by continuous Mexican (MEX) and Haar (HA) transforms. Finally, a zero-crossing technique was applied on the transformed signal and the constructed calibration was tested by analyzing the composition of the different mixture containing CA and PR. All calculations have been performed within EXCEL and Matlab 6.5 software. The obtained results indicate that our procedure is flexible and applicable for the mixture analysis.

Antipyrine↗

PubMed2003

Linear regression analysis and its application to the multivariate spectral calibrations for the multiresolution of a ternary mixture of caffeine, paracetamol and metamizol in tablets.

The multivariate spectral calibration methods, tri-linear regression-calibration (TLRC) and multi-linear regression-calibration (MLRC) were developed for the multiresolution of a ternary mixture of caffeine (CAF), paracetamol (APAP), metamizol (MET), which have closely overlapped in the spectra. The calibration algorithms were briefly described for the three-component system, CAF-APAP-MET. By using the various synthetic mixtures of three compounds, the validity of the TLRC and MLRC methods was confirmed and applied to the real samples containing the above-mentioned compounds in two different commercial tablet formulations. The TLCR and MLRC methods which are very rapid, easy to apply, yet not expensive, are powerful tools with very simple mathematical contents for multiresolution of the three- or multi-component mixture systems. The data treatments were carried out by the MAPLE V, EXCEL and SPSS 10.0 Softwares. The obtained results were successfully compared with each other as well as with those obtained by other literature methods.

Acetaminophen↗

PubMed2003

Simultaneous spectrophotometric determination of cyproterone acetate and estradiol valerate in pharmaceutical preparations by ratio spectra derivative and chemometric methods.

Ratio spectra derivative spectrophotometry and two chemometric methods (classical least squares, CLS and inverse least squares, ILS, were proposed for the simultaneous quantitative analysis of a binary mixture consists of cyproterone acetate (CA) and estradiol valerate (EV) in the commercial pharmaceutical preparations. In the ratio spectra derivative method, linear regression equations for both drugs were obtained by measuring the analytical signals at the wavelenghts corresponding to either maximums and minimums in the first derivative spectra of the ratio spectra. In the chemometric techniques, the concentration matrix was prepared by using the synthetic mixtures containing these drugs. The absorbance matrix corresponding to the concentration matrix was obtained by measuring the absorbances at 14 wavelengths in the range 220-290 nm for the zero-order spectra. Two chemometric calibrations were constructed by using the absorbance matrix and concentration matrix for the prediction of the unknown concentrations of CA and EV in their mixture. The numerical values were calculated by using 'MAPLE V' software. The accuracy and the precision of the methods have been determined and they have been validated by analyzing synthetic mixtures containing these two drugs. The proposed methods were successfully applied to a pharmaceutical formulation, sugar-coated tablet, and the results were compared with each other.

Algorithms↗

PubMed2003

A zero-crossing technique for the multidetermination of thiamine HCl and pyridoxine HCl in their mixture by using one-dimensional wavelet transform.

A new zero-crossing technique based on one-dimensional wavelet transform (WT) was developed and applied on a commercial vitamin product and binary mixtures containing thiamine HCl and pyridoxine HCl in the presence of the interference of the analysed signals. We selected from the data of the UV-Vis absorption spectra a signal consisting of 1150 points corresponding to the concentration range 8-32 mg/ml for both vitamins and we subjected it to one-dimensional continuous WT Mexican (MEXICAN) and Meyer (MEYER). Since the peaks of the transformed signals were bigger than original ones a zero crossing technique was applied to obtain the regression equations. The validity of Beer-Lambert law was assumed for the transformed signals. An appropriate scale setting was choosing to obtain an alternative calibration for each method. The basic concepts about wavelet method were briefly explained and MATLAB 6.5 software was used for one-dimensional wavelet analysis. The obtained results were successfully compared among each other and with those obtained by other literature methods. The developed method is rapid, easy to apply, not expensive and suitable for analysing of the overlapping signals of compounds in their mixtures without any chemical pre-treatment.

Algorithms↗

PubMed2003

Spectophotometric quantitative resolution of hydrochlorothiazide and spironolactone in tablets by chemometric analysis methods.

Spectrophotometric simultaneous determination of hydrochlorothiazide and spironolactone in tablets was performed by classical least-squares (CLS), inverse least-squares (ILS), principal component regression (PCR) and partial least-squares (PLS). The methods of the chemometric analysis do not require sample pretreatment procedure. A training set of 25 standard mixture containing both drugs was prepared in the concentration range of 2-20 mug/ml according to mixture design. The multivarate calibrations were obtained by measuring the zero-order and first-derivative absorbances at 15 points from 220 to 290 nm using the training set. The validation of the multivariate methods was realised by analysing the synthetic mixtures of hydrochlorothiazide and spironolactone. The result obtained on the synthetic mixture and tablets were statistically compared by the one-way ANOVA test. The chemometrics analysis methods were satisfactorily applied to the simultaneous determination of hydrochlorothiazide and spironolactone in the pharmaceutical tablet formulation.

Hydrochlorothiazide↗

PubMed2002

Spectrophotometric quantitative determination of cilazapril and hydrochlorothiazide in tablets by chemometric methods.

Four chemometric methods were applied to simultaneous determination of cilazapril and hydrochlorothiazide in tablets. Classical least-square (CLS), inverse least-square (ILS), principal component regression (PCR) and partial least-squares (PLS) methods do not need any priori graphical treatment of the overlapping spectra of two drugs in a mixture. For all chemometric calibrations a concentration set of the random mixture consisting of the two drugs in 0.1 M HCI and methanol (1:1) was prepared. The absorbance data in the UV-Vis spectra were measured for the 15 wavelength points (from 222 to 276 nm) in the spectral region 210-290 nm considering the intervals of deltalambda = 4 nm. The calibration of the investigated methods involves only absorbance and concentration data matrices. The developed calibrations were tested for the synthetic mixtures consisting of two drugs and using the Maple V software the chemometric calculations were performed. The results of the methods were compared each other as well as with HPLC method and a good agreement was found.

Algorithms↗

PubMed2002

Chemometric resolution of a mixture containing hydrochlorothiazide and amiloride by absorption and derivative spectrophotometry.

Four chemometric techniques, classical least squares (CLS) and inverse least squares (ILS) and principal component regression (PCR) and partial least squares regression (PLSR) were applied to the absorption and derivative spectrophotometric determinations of amiloride and hydrochlorothiazide in a pharmaceutical preparation. Four chemometric calibrations for both zero-order and first derivative spectra were constructed by measuring the absorbance and their dA/dlambda values at 34 points in the wavelength range 205-395 nm for a training set containing 2-10 microg/ml amiloride and 4-28 microg/ml hydrochlorothiazide corresponding to 25 point mixture design. The building chemometric calibrations were confirmed by using the synthetic mixtures containing two drugs. The results obtained by the proposed techniques based on the use of the measurements at the absorption spectra and at the first derivative spectra were statistically compared with each other.

Amiloride↗

PubMed2002

Simultaneous spectrophotometric determination of mefenamic acid and paracetamol in a pharmaceutical preparation using ratio spectra derivative spectrophotometry and chemometric methods.

Four new methods are described for the simultaneous determination of mefenamic acid (MEF) and paracetamol (PAR) in their combination. In the first method, ratio spectra derivative method, analytical signals were measured at the wavelengths corresponding to either maximums or minimums for both drugs in the first derivative spectra of the ratio spectra obtained by dividing the standard spectrum of one of two drugs in 0.1 M NaOH:methanol (1:9). In the chemometric techniques, classical least-squares, inverse least-squares and principal component regression (PCR), the training was randomly prepared by using the different mixture compositions containing two drugs in 0.1 M NaOH:methanol (1:9). The absorbance data was obtained by the measurements at 13 points in the wavelength range 235-355 nm in the absorption spectra. Chemometric calibrations were constructed by the absorbance data and training set for the prediction of the amount of MEF and PAR in samples. In the third chemometric method, PCR, the covariance matrix corresponding to the absorbance data was calculated for the basis vectors and matrix containing the new coordinates. The obtained calibration was used to determine the title drugs in their mixture. Linearity range in all the methods was found to be 2-10 microg/ml of MEF and 4-20 microg/ml of PAR. Mean recoveries were found satisfactory (>99%). The procedures do not require any separation step. These methods were successfully applied to a pharmaceutical formulation, tablet, and the results were compared with each other.

Acetaminophen↗

PubMed2002

Spectrophotometric multicomponent resolution of a veterinary formulation containing oxfendazole and oxyclozanide by multivariate calibration-prediction techniques.

Four multivariate calibration-prediction techniques, classical least-squares, inverse least-squares, principal component regression and partial least-squares regression were applied to the spectrophotometric multicomponent analysis of a veterinary formulation containing oxfendazole (OXF) and oxyclozanide (OXC) without any separation step. The multivariate calibrations were constructed by measuring the absorbance values at 14 points in the 285-350 nm wavelength range and by using the training set of standard mixtures containing OXF and OXC in the different compositions. The validity of building multivariate calibrations was checked by using the synthetic mixtures of both drugs. The multivariate calibration models were successfully applied to the spectrophotometric determination of OXF and OXC in laboratory prepared mixtures and a veterinary formulation. The results obtained were statistically compared with each other.

Algorithms↗

PubMed2002

Simultaneous spectrophotometric determination of chlorphenoxamine hydrochloride and caffeine in a pharmaceutical preparation using first derivative of the ratio spectra and chemometric methods.

Three new methods are described for the simultaneous determination of chlorphenoxamine hydrochloride (CP) and caffeine (CAF) in their combination. In the first method, ratio spectra derivative spectrophotometry, analytical signals were measured at the wavelengths corresponding to either maxima and minima for both drugs in the first derivative spectra of the ratio spectra obtained by using each other spectra as divisor in their solution in 0.1 M HCl. In the other two methods, chemometric techniques, classical least-squares (CLS) and inverse least-squares (ILS), the concentration data matrix were prepared by using the synthetic mixtures containing these drugs in 0.1 M HCl. The absorbance data matrix corresponding to the concentration data matrix was obtained by the measurements of absorbances in the range 225-285 nm in the intervals with Deltalambda = 5 nm at 13 wavelengths in their zero-order spectra, then, calibration or regression was obtained by using the absorbance data matrix and concentration data matrix for the prediction of the unknown concentrations of CP and CAF in their mixture. The numerical values were calculated by using MAPLE V software in chemometric methods. The procedures do not require any separation step. The accuracy and the precision of the methods have been determined and they have been validated by analyzing synthetic mixtures containing title drugs. These three methods were successfully applied to a pharmaceutical formulation, sugar-coated tablet, and the results were compared with each other.

Algorithms↗

PubMedDate not supplied

Linear regression analysis and its application to multivariate chromatographic calibration for the quantitative analysis of two-component mixtures.

Multivariate chromatographic calibration technique was developed for the quantitative analysis of binary mixtures enalapril maleate (EA) and hydrochlorothiazide (HCT) in tablets in the presence of losartan potassium (LST). The mathematical algorithm of multivariate chromatographic calibration technique is based on the use of the linear regression equations constructed using relationship between concentration and peak area at the five-wavelength set. The algorithm of this mathematical calibration model having a simple mathematical content was briefly described. This approach is a powerful mathematical tool for an optimum chromatographic multivariate calibration and elimination of fluctuations coming from instrumental and experimental conditions. This multivariate chromatographic calibration contains reduction of multivariate linear regression functions to univariate data set. The validation of model was carried out by analyzing various synthetic binary mixtures and using the standard addition technique. Developed calibration technique was applied to the analysis of the real pharmaceutical tablets containing EA and HCT. The obtained results were compared with those obtained by classical HPLC method. It was observed that the proposed multivariate chromatographic calibration gives better results than classical HPLC.

Calibration↗

PubMedDate not supplied

Multicomponent quantitative resolution of binary mixtures by using continuous wavelet transform.

Continuous 1-dimensional wavelet transform (WT) was applied to the quantitative analysis of a vitamin combination of thiamine hydrochloride (THI) and pyridoxine hydrochloride (PYR) with strongly overlapping signals. Absorbance data from the UV-Vis absorption spectrum of width 1150 were subjected to Gauss1 and Gauss2 WTs. Because of its flexibility, data processing, and its high signal amplitude, the continuous WT method is a powerful tool for analysis of multicomponent mixtures. By measuring the amplitude signals corresponding to the selected zero-crossing points of the transformed signal, we obtained the calibration curve. The validation of the calibration graphs was confirmed with different mixtures of THI and PYR at various concentration ratios. A brief explanation of the continuous wavelet method is given. MATLAB 6.5 software was used to perform the calculations. The results of our study were compared with those obtained by spectroscopic, chemometric, and liquid chromatographic methods, and good agreement was found.

Calibration↗

PubMedDate not supplied

Application of the wavelet method for the simultaneous quantitative determination of benazepril and hydrochlorothiazide in their mixtures.

The discrete and continuous wavelet transforms were applied to the overlapping signal analysis of the ratio data signal for simultaneous quantitative determination of the title subject compounds in samples. The ratio spectra data of the binary mixtures containing benazepril (BE) and hydrochlorothiazide (HCT) were transferred as data vectors into the wavelet domain. Signal compression, followed by a 1-dimension continuous wavelet transform (CWT), was used to obtain coincident transformed signals for pure BE and HCT and their mixtures. The coincident transformed amplitudes corresponding to both maximum and minimum points allowed construction of calibration graphs for each compound in the binary mixture. The validity of CWT calibrations was tested by analyzing synthetic mixtures of the investigated compounds, and successful results were obtained. All calculations were performed within EXCEL, C++, and MATLAB6.5 softwares. The obtained results indicated that our approach was flexible and applicable for the binary mixture analysis.

Algorithms↗