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

UV-VIS spectrophotometric-assisted chemometric calibration models for simultaneous determination of thiamine and pyridoxine vitamins in powdered infant formula

Thiamine and pyridoxine, which are hydrophilic B vitamins, are compounds that play an important role in many biochemical events for the health of infants and adults. Recently, because of the complexity of food and pharmaceutical composition, chemometric models are preferred to obtain relevant information from multivariate measured data. The aim of this study was to determine the simultaneous quantitative analysis of thiamine and pyridoxine in powdered infant formula and pharmaceutical formulations by the UV-visible spectrophotometric method coupled with chemometric calibration models (partial least squares (PLS) and principal component regression (PCR)). These vitamins were extracted by addition of trichloroacetic acid (precipitation of proteins) after samples of powdered infant formula was dissolved in Milli-Q water. Factorial design was used to prepare the calibration (25 samples) and validation (8 samples) sets containing mixture of thiamine and pyridoxine within their linear range (2.5-25 μg/mL). Spectra of obtained mixtures and samples were recorded between wavelengths of 200-360 nm with the intervals Δλ=1 nm. In regression models created by using PLS and PCR algorithm, the results had acceptable recovery 98.14% for both compounds. These chemometric models predict the quantification of both, thiamine and pyridoxine in powdered infant formula samples via interpreting the UV-Vis spectrum. The average thiamine and pyridoxine contents of powdered infant formula samples were found to be 5.02±0.065 μg/g and 4.32±0.086 μg/g for PLS model and 4.98±0.078 μg/g and 4.03±0.091 μg/g for PCR model, respectively.

Development of UV-visible spectrophotometric methods for the quantitative and in silico studies for cilazapril optimized by response surface methodology

For cilazapril (CLZ), analytical methods based on donor-acceptor phenomenon that are simple, rapid with broad linear dynamic range for the quantification of drug are not available in the literature. Considering the requirement for the methods, in this study, two economic, potent analytical methods based on the complexation of CLZ with π-acceptors, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,5-dichloro-3,6-dihydroxy-p-benzoquinone (CA) were developed, validated, and studied spectrophotometrically. Various analytical data were discussed. The effects of experimental variables were optimized from the results of in silico technique, i.e. Box-Behnken design under response surface methodology. Linear dynamic range was significantly good in the range of 6-60 µg mL^-1 and 20-260 µg mL^-1 for DDQ and CA methods. Moreover, molecular docking studies corroborated the experimental results. Further, the methods were supplemented by the pharmaceutical and biological application for the quantitative assay of CLZ. Collectively, the results of the reported method of the analysis suggest that the developed approach is simple, sensitive, accurate and precise.

Improved intracellular PHA determinations with novel spectrophotometric quantification methodologies based on Sudan black dye

The presence of intracellular polyhydroxyalkanoates (PHAs) is usually studied using Sudan black dye solution (SB). In a previous work it was shown that the PHA could be directly quantified using the absorbance of SB fixed by PHA granules in wet cell samples. In the present paper, the optimum SB amount and the optimum conditions to be used for SB assays were determined following an experimental design by hybrid response surface methodology and desirability-function. In addition, a new methodology was developed in which it is shown that the amount of SB fixed by PHA granules can also be determined indirectly through the absorbance of the supernatant obtained from the stained cell samples. This alternative methodology allows a faster determination of the PHA content (involving 23 and 42 min for indirect and direct determinations, respectively), and can be undertaken by means of basic laboratory equipment and reagents. The correlation between PHA content in wet cell samples and the spectra of the SB stained supernatant was determined by means of multivariate and linear regression analysis. The best calibration adjustment (R² = 0.91, RSE: 1.56%), and the good PHA prediction obtained (RSE = 1.81%), shows that the proposed methodology constitutes a reasonably precise way for PHA content determination. Thus, this methodology could anticipate the probable results of the above mentioned direct PHA determination. Compared with the most used techniques described in the scientific literature, the combined implementation of these two methodologies seems to be one of the most economical and environmentally friendly, suitable for rapid monitoring of the intracellular PHA content.

Chemometrics-Assisted UV Spectrophotometric and RP-HPLC Methods for the Simultaneous Determination of Tolperisone Hydrochloride and Diclofenac Sodium in their Combined Pharmaceutical Formulation

Chemometrics-assisted UV spectrophotometric and RP-HPLC methods are presented for the simultaneous determination of tolperisone hydrochloride (TOL) and diclofenac sodium (DIC) from their combined pharmaceutical dosage form. Chemometric methods are based on principal component regression and partial least-square regression models. Two sets of standard mixtures, calibration sets, and validation sets were prepared. Both models were optimized to quantify each drug in the mixture using the information included in the UV absorption spectra of the appropriate solution in the range 241-290 nm with the intervals λ = 1 nm at 50 wavelengths. The optimized models were successfully applied to the simultaneous determination of these drugs in synthetic mixture and pharmaceutical formulation. In addition, an HPLC method was developed using a reversed-phase C18 column at ambient temperature with a mobile phase consisting of methanol:acetonitrile:water (60:30:10 v/v/v), pH-adjusted to 3.0, with UV detection at 275 nm. The methods were validated in terms of linearity, accuracy, precision, sensitivity, specificity, and robustness in the range of 3-30 μg/mL for TOL and 1-10 μg/mL for DIC. The robustness of the HPLC method was tested using an experimental design approach. The developed HPLC method, and the PCR and PLS models were used to determine the amount of TOL and DIC in tablets. The data obtained from the PCR and PLS models were not significantly different from those obtained from the HPLC method at 95% confidence limit.

Simultaneous Analysis of Losartan Potassium, Amlodipine Besylate, and Hydrochlorothiazide in Bulk and in Tablets by High-Performance Thin Layer Chromatography with UV-Absorption Densitometry

A Simple high-performance thin layer chromatography (HPTLC) method for separation and quantitative analysis of losartan potassium, amlodipine, and hydrochlorothiazide in bulk and in pharmaceutical formulations has been established and validated. After extraction with methanol, sample and standard solutions were applied to silica gel plates and developed with chloroform : methanol : acetone : formic acid 7.5 : 1.3 : 0.5 : 0.03 (v/v/v/v) as mobile phase. Zones were scanned densitometrically at 254 nm. The R(f) values of amlodipine besylate, hydrochlorothiazide, and losartan potassium were 0.35, 0.57, and 0.74, respectively. Calibration plots were linear in the ranges 500-3000 ng per spot for losartan potassium, amlodipine and hydrochlorothiazide, the correlation coefficients, r, were 0.998, 0.998, and 0.999, respectively. The suitability of this method for quantitative determination of these compounds was by validation in accordance with the requirements of pharmaceutical regulatory standards. The method can be used for routine analysis of these drugs in bulk and in formulation.

Simultaneous spectrophotometric determination of losartan potassium, amlodipine besilate and hydrochlorothiazide in pharmaceuticals by chemometric methods

In the present work, four different spectrophotometric methods for simultaneous estimation of losartan potassium, amlodipine besilate and hydrochlorothiazide in raw materials and in formulations are described. Overlapped data was quantitatively resolved by using chemometric methods, classical least squares (CLS), multiple linear regression (MLR), principal component regression (PCR) and partial least squares (PLS). Calibrations were constructed using the absorption data matrix corresponding to the concentration data matrix, with measurements in the range of 230.5-350.4 nm (Δλ = 0.1 nm) in their zero order spectra. The linearity range was found to be 8-40, 1-5 and 3-15 μg mL-1 for losartan potassium, amlodipine besilate and hydrochlorothiazide, respectively. The validity of the proposed methods was successfully assessed for analyses of drugs in the various prepared physical mixtures and in tablet formulations.

Derivative and Q-analysis Spectrophotometric Methods for Estimation of Hydrochlorothiazide and Olmesartan Medoxomil in Tablets

Two methods for simultaneous estimation of hydrochlorothiazide and olmesartan medoxomil in combined tablet dosage form have been developed. The first method is the application of Q-analysis method (absorbance ratio), which involves the formation of Q-absorbance equation at 264 nm (isobestic point) and at 271 nm, the maximum absorption of hydrochlorothiazide. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-22.5 mug/ml and 4-36 mug/ml, respectively. The second method is based on the derivative spectrophotometric method at zero crossing wavelengths. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-20 mug/ml and 4-32 mug/ml, respectively. The accuracy of the methods were assessed by recovery studies and was found to be 100.45% +/-0.4215 and 100.24% +/-0.3783 for absorbance ratio method and 99.39% +/-0.221 and 99.72% +/-0.11 for first derivative method, for hydrochlorothiazide and olmesartan medoxomil, respectively. These methods are simple, accurate and rapid, those require no preliminary separation and can therefore be used for routine analysis of both drugs in quality control laboratories.

Continuous wavelet and derivative transforms for the simultaneous quantitative analysis and dissolution test of levodopa–benserazide tablets

Simultaneous analyses and dissolution tests of levodopa-benserazide tablets were carried out by continuous wavelet transform (CWT) and classic derivative spectrophotometry (DS) without using any chemical separation step. The developed two spectrophotometric resolutions are based on the transformation of the original UV spectra. The original absorption spectra of levodopa and benserazide in the concentration range of 1-80 microg/mL and 5-240 microg/mL in USP simulated gastric juice were registered in the spectral range of 250-310 nm, respectively. Various wavelet families and different spectrophotometric derivative orders were tested to find the optimal signal processing for obtaining desirable calibration graphs and reliable determinations of the investigated drugs. Under the optimized conditions of the methods, symlets wavelet family using a=128 with sixth order (SYM6-CWT) and the first derivative transform with Deltalambda=10nm were identified as optimal signal processing methods for the determinations and dissolution tests. The calibration functions for each drug were obtained by measuring the values of the CWT and derivative amplitudes. The validation of the developed methods was confirmed by analyzing various synthetic mixtures of the investigated drugs. Mean recovery values were found between 99.1% and 104.7% for DS and 100% and 102.9% for CWT, respectively for determination of BEN and LEV in synthetic mixtures. Each developed approaches were successfully applied to the simultaneous determination and dissolution test of levodopa and benserazide in their commercial tablets and a good agreement was observed.

Vibrational and microbiological study on alkaline metal picolinates and o-iodobenzoates

FT-IR and Raman experimental data were assigned to appropriate bond vibrations and used to compare the different electronic charge distributions in the aromatic rings and carboxylic anions of various lithium, sodium, potassium, rubidium and caesium o-iodobenzoates and picolinates. Then principal component analysis (PCA) was applied in order to attempt to distinguish the biological activities of these compounds according to selected band wavenumbers. The growth of the bacteria Escherichia coli and Bacillus subtilis and the yeasts Saccharomyces cerevisiae and Hansenula anomala under optimal growth conditions were measured after 24 hours of incubation by the classical plate method. The influence of the picolinates and o-iodobenzoates on the growth of these microorganisms, again after 24 hours of incubation, was also measured and compared to the effect of sodium benzoate, which was used as a reference material. In general, the o-iodobenzoates exhibited more activity against the microorganisms than the picolinates. A statistically significant linear correlation between the spectral data and the degree of influence of a given compound on microorganism growth was established. The correlation coefficients for the o-iodobenzoates were 0.696, -0.628, 0.693 and 0.755 for E. coli, B. subtilis, H. anomala and S. cerevisiae, respectively, and for the picolinates they were 0.818, 0.826, 0.821 and 0.877 for E. coli, B. subtilis, H. anomala and S. cerevisiae, respectively. Therefore, IR spectroscopy is shown to be a rapid and reliable analytical tool for preliminary estimation of the antimicrobial properties of newly synthesized compounds, that can be applied before microbial performance tests.

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.

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.