Erdal Dinç

Spectrophotometric multicomponent determination of sunset yellow, tartrazine and allura red in soft drink powder by double divisor-ratio spectra derivative, inverse least-squares and principal component regression methods

Double divisor-ratio spectra derivative (graphical method), classical least-squares and principal component regression (two numerical methods) methods were developed for the spectrophotometric multicomponent analysis of soft drink powders and synthetic mixtures containing three colorants without any chemical separation. The graphical method is based on the use of derivative signals of the ratio spectra using double divisor. In this method, the linear determination ranges were 2-8 mug ml(-1) sunset yellow, 4-18 mug ml(-1) tartrazine and 2-8 mug ml(-1) allura red in 0.1 M HCl. In the numerical methods, a training set was randomly prepared by using 18 samples containing between 0 and 8 mug ml(-1) of sunset yellow, 0-18 mug ml(-1) of tartrazine and 0-8 mug ml(-1) of allura red. The chemometric calibrations were calculated by using the prepared training set and its absorbances at seven points (from 375.0 to 550.0 nm) in the spectral region 325-584 nm. The proposed methods were validated by using synthetic ternary mixtures and applied to the simultaneous determination of three colorants in soft drink powders. The obtained results were statistically compared with each other.

Application of a new spectrophotometric method for the analysis of a ternary mixture containing metamizol, paracetamol and caffeine in tablets

A new spectrophotometric method was developed for the simultaneous analysis of a ternary mixture, without prior separation. This method is based on the use of the derivative of the ratio spectrum obtained by dividing the absorption spectrum of the ternary mixture by a standard spectrum of a mixture of two of the three compounds in the title mixture. The concentrations of three compounds in their mixture are determined by using their respective calibration graphs which are obtained by measuring the amplitude at either the maximum or minimum wavelengths selected. The mathematical explanation of the procedure is illustrated. The method was applied for the assay of tablets containing metamizol, caffeine and paracetamol. The developed method was compared with alternative spectrophotometric methods.

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.

The spectrophotometric multicomponent analysis of a ternary mixture of ascorbic acid, acetylsalicylic acid and paracetamol by the double divisor-ratio spectra derivative and ratio spectra-zero crossing methods

The double divisor-ratio spectra derivative and ratio spectra-zero crossing methods were applied to the analysis of an effervescent tablet containing the title compounds without using a chemical separation procedure. In the use of both methods, the calibration graphs were linear in the range of 8-28 microg ml(-1) for three compounds. Comparison of the results obtained by the two methods indicates that both methods gives the best results.

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.

An application of derivative and continuous wavelet transforms to the overlapping ratio spectra for the quantitative multiresolution of a ternary mixture of paracetamol, acetylsalicylic acid and caffeine in tablets

Quantitative multiresolution of tablets and ternary mixtures of paracetamol (PAR), acetylsalicylic acid (ASP) and caffeine (CAF) having strongly overlapping spectra was accomplished by two graphical transform methods as ratio spectra first derivative-zero crossing and ratio spectra-continuous wavelet transform-zero crossing (ratio spectra CWT-zero crossing) methods. In this study, ratio spectra derivative-zero crossing and ratio spectra CWT-zero crossing methods are based on the use of transformed signals of the ratio spectra and their calibration graphs were obtained by measuring the dA/dlambda and CWT amplitudes of the ratio spectra corresponding to zero crossing points. For the comparison purpose, PLS calibration method was applied to predict the content of the same mixtures containing the subject active compounds. The obtained calibrations were tested by using the synthetic mixtures and standard addition technique and they applied to the simultaneous determination of PAR, ASP and CAF in commercial pharmaceutical preparation. The obtained results were statistically compared with each other as well as those obtained by HPLC method and they showed good agreement.

Derivative ratio spectra-zero crossing spectrophotometry and LC method applied to the quantitative determination of paracetamol, propyphenazone and caffeine in ternary mixtures.

Two methods were used to determine paracetamol, caffeine and propyphenazon in ternary mixtures and tablets. Derivative ratio spectra-zero crossing procedure was based on the simultaneous use of the first derivative of ratio spectra and measurements of derivative ratio analytical signals corresponding to the zero crossing points of wavelengths. By using propyphenazon as a divisor, the amounts of paracetamol and caffeine in the ternary mixture were determined by measuring the first derivative ratio amplitudes at 242.8 nm (zero-crossing point for caffeine) and 251.2 and 273.8 nm (zero-crossing point for paracetamol) respectively. Also by using paracetamol as a divisor, the contents of propyhenazon and caffeine in the same ternary mixture were determined by measuring the first derivative ratio amplitudes at 244.8 and 276.9 nm (zero-crossing point for caffeine) and 250.6 and 274.0 nm (zero-crossing point for propyphenazon), respectively. For the HPLC procedure, a Nucleosil C18 column and a mobile phase consisted of water and methanol (20:80) were used to separate three compounds with cetrimide as an internal standard. The flow rate was 1.0-ml/min with an ultraviolet (UV) detection at 254 nm. Both methods were also applied to the determination of these three compounds in ternary mixtures and tablet formulation. The analytical results were quite good in all cases.

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.

An Approach to Quantitative Two‐Component Analysis of a Mixture Containing Hydrochlorothiazide and Spironolactone in Tablets by One‐Dimensional Continuous Daubechies and Biorthogonal Wavelet Analysis of UV‐Spectra

In this study a new method of quantitative two‐component analysis of a mixture of hydrochlorothiazide (HCT) and spironolactone (SP) in the presence of strongly overlapping signals was achieved by using one‐dimensional continuous wavelet analysis. This new method was built on the simultaneous use of both continuous wavelet transform and the zero crossing technique for the quantitative resolution of this binary mixture. A series of solutions, in the concentration range of 2–22 mg/ml for both compounds, in methanol and 0.2 M sodium acetate buffer, pH = 5 (20:80), were considered. The absorption spectra of the standard solutions were recorded in the wavelength range of 215–330 nm. To apply our methods we selected 400 points from the absorption spectra and we subjected the corresponding signal to Daubechies2 (DAUB2) and Biorthogonal1.5 (BIOR1.5) one‐dimensional wavelet transform. In the transformed signals, the amplitude of HCT was measured at the position of a zero crossing point of SP and vice versa. Thus simple linear regression analysis can be applied to establish calibrations for both components. These calibrations were validated with synthetic mixtures of HCT and SP. MATLAB 6.5 software was used for one‐dimensional wavelet analysis, and the basic concepts about wavelet method are briefly explained. The method developed in this paper is rapid, easy to apply, inexpensive and it is suitable for analysis of the overlapping signals of compounds in their mixtures without any chemical pre‐treatment.

Multidetermination of thiamine HCl and pyridoxine HCl in their mixture using continuous daubechies and biorthogonal wavelet analysis.

A new graphical method based on the one-dimensional wavelet transform (WT) was proposed and tested on mixture of thiamine hydrochloride (THI) and pyridoxine hydrochloride (PYR) in the presence of strongly overlapping 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(-1) for each vitamin and we subjected it to Daubechies8 (DAUB8) and Biorthogonal6.8 (BIOR6.8) wavelet transforms. Since the peaks of the transformed signals were bigger than original ones a zero crossing method was applied to obtain the calibration graphs. In addition, 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. Matlab 6.5 software was used for one-dimensional wavelet analysis and the basic concepts about wavelet method were given. The obtained results were successfully compared among each other as well as with those obtained by other literature methods. The method developed in this paper is rapid, easy to apply, not expensive and it is suitable for analyzing of the overlapping signals of compounds in their mixtures without any chemical pre-treatment.