Response surface methodology combined Box-Behnken design optimized green kinetic spectrophotometric and HPLC methods to quantify angiotensin receptor blocker valsartan in pharmaceutical formulations.

The high-performance liquid chromatographic (HPLC) and kinetic spectrophotometric methods were established to compute valsartan (VAL) in pharmaceutical formulations. The spectrophotometric procedures adopted initial rate, fixed time, and equilibrium strategies to assess VAL. The method was based on the carboxylic acid group of the oxidized VAL with a mixture of potassium iodate (KIO3) and potassium iodide (KI) at room temperature, producing a stable, yellow-coloured absorb at 352 nm. The critical parameters were optimized using green process optimization methodology such as Box-Behnken design (BBD) which belongs to response surface methodology (RSM). After the screening, experiments identified them as significant, and then three crucial factors were optimised: KI volume, KIO3 volume, and reaction time against response as absorbance. The HPLC procedure was also optimized based on the desirability function on RSM-BBD. The parameters such as pH, methanol (%), and flow rate (ml/min) were optimized with the best responses: peak area, symmetry, and theoretical plates. The linearity of spectrophotometric and HPLC methods was within the range of 2-24 and 0.25-11.25 µg/ml, respectively. The developed procedures produced excellent accuracy and precision. The design of the experiment (DoE) setting explained and discussed the individual steps and the importance of independent and dependent variables used to develop the model and optimization. The method was validated as per the International Conference on Harmonization (ICH) guidelines. Furthermore, Youden's robustness study was applied with factorial combinations of the preferred analytical parameters and explored their influence with alternative conditions. The analytical Eco-Scale score was calculated and was found a better option as green methods to quantify VAL. The results were reproducible with the analysis completed with biological fluid and wastewater samples.

Development of a Citric-Acid-Modified Cellulose Adsorbent Derived from Moringa peregrina Leaf for Adsorptive Removal of Citalopram HBr in Aqueous Solutions.

A citric-acid-modified Moringa peregrina leaf substrate was prepared and studied as an effective adsorbent for the adsorptive removal of citalopram HBr (CTM). FTIR spectra were utilized to characterize the prepared solid. The effects of experimental variables on the percentage removal of citalopram HBr were investigated using response surface methodology. The optimum conditions selected for removal of CTM were 7 and 4 min, 0.17 g per 50 mL and 35 mg·L-1 for pH, contact time, adsorbent dose and initial concentration of CTM, respectively. Under the optimized experimental conditions, 82.59% CTM (35 mg·L-1) was removed. The Langmuir isotherm, Freundlich isotherm, pseudo second-order kinetic model and diffusion-chemisorption model explained the adsorption data successfully. The maximum adsorption capacity at 298 K was 8.58 mg·g-1. A thermodynamic study illustrated that CTM adsorption was spontaneous and endothermic in nature.

Optimization for synthesis of silver nanoparticles through response surface methodology using leaf extract of Boswellia sacra and its application in antimicrobial activity.

In the present work, leaf extract of Boswellia sacra was used as reductant for synthesis of silver nanoparticles (AgNPs). The variables such as volume of Boswellia sacra leaf extract (1%), volume of silver nitrate (1 mM), and temperature were optimized by response surface methodology via Box-Behnken design for the synthesis of AgNPs. Design-Expert software generated the optimum conditions for the highest yield of silver nanoparticles as 8 mL of 1 mM AgNO3, 8 mL of 1% Boswellia sacra leaf extract, and temperature = 55 °C. The formed AgNPs were isolated and purified by centrifugation process using ethanol/ distilled water. AgNPs were characterized using FTIR, SEM, TEM, EDX, and XRD. AgNPs showed surface plasmon resonance absorption band at 422 nm. XRD pattern indicated the crystalline nature of the particles (diameter 11.17 to 37.50 nm) with face-centered cubic structure. SEM and TEM images highlighted the formation of spherical AgNPs. The energy dispersive spectroscopic spectrum confirmed the presence of elemental silver. The microbial activity of AgNPs was evaluated against bacteria and fungi. Synthesized AgNPs were very effective against Gram-positive E. coli bacterial strains and fungal strains (Penicillium chrysogenum).

Utility of eosin Y as a complexing reagent for the determination of citalopram hydrobromide in commercial dosage forms by fluorescence spectrophotometry.

An accurate, selective and sensitive spectrofluorimetric method was developed for the determination of citalopram hydrobromide in commercial dosage forms. The method was based on the formation of a fluorescent ion-pair complex between citalopram hydrobromide and eosin Y in the presence of a disodium hydrogen phosphate/citric acid buffer solution of pH 3.4 that was extractable in dichloromethane. The extracted complex showed fluorescence intensity at λem = 554 nm after excitation at 259 nm. The calibration curve was linear over at concentrations of 2.0-26.0 µg/mL. Under optimized experimental conditions, the proposed method was validated as per ICH guidelines. The effect of common excipients used as additives was tested and the tolerance limit calculated. The limit of detection for the proposed method was 0.121 µg/mL. The proposed method was successfully applied to the determination of citalopram hydrobromide in commercial dosage forms. The results were compared with the reference RP-HPLC method.

Utility of cefixime as a complexing reagent for the determination of Ni(II) in synthetic mixture and water samples.

A simple, sensitive, and accurate UV spectrophotometric method has been developed for the determination of nickel in synthetic mixture and water samples. The method is based on the complexation reaction of nickel ion with cefixime, thus leading to the formation of Ni-cefixime complex in ethanol-distilled water medium at room temperature. The complex showed the maximum absorption wavelength at 332 nm. Beer's law is obeyed in the working concentration range of 0.447-4.019 µg mL(-1) with apparent molar absorptivity of 7.314 × 10(3) L mol(-1) cm(-1) and Sandell's sensitivity of 0.008 µg/cm(2)/0.001 absorbance unit. The limits of detection and quantitation for the proposed method are 0.016 and 0.054 µg mL(-1), respectively. The factors such as cefixime concentration and solvent affecting the complexation reaction were carefully studied and optimized. The method is validated as per the International Conference on Harmonisation guideline. The method is successfully applied to the determination of Ni(II) in synthetic mixture and wadi water samples collected from Al Rustaq. The same water samples are also analyzed by atomic absorption spectrophotometry. Both methods determined the amount of Ni(II) in water sample and found to be approximately the same.

Quantitative analysis of cefixime via complexation with palladium(II) in pharmaceutical formulations by spectrophotometry.

An optimized and validated spectrophotometric method has been developed for the determination of cefixime in pharmaceutical formulations. The method is based on the complexation reaction between cefixime and palladium ion in the presence of acidic buffer solution (pH 3) in ethanol-distilled water medium at room temperature. The complex absorbed maximally at 352 nm. Beer's law is obeyed in the working concentration range of 2.5-35 µg/mL with apparent molar absorptivity of 1.015×104 L/mol cm and Sandell's sensitivity of 0.001 µg/cm2/0.001 absorbance unit. The limits of detection and quantitation for the proposed method are 0.175 and 0.583 µg/mL, respectively. The effect of common excipients used as additives has been studied in the determination of cefixime. The proposed method has been successfully applied for the determination of cefixime in pharmaceutical formulations. The results obtained by the proposed method were statistically compared with the reference method using t and F values and found no significant difference between the two methods.

Spectrofluorimetric method for the determination of doxepin hydrochloride in commercial dosage forms.

A novel spectrofluorimetric method has been developed for the determination of doxepin hydrochloride in commercial dosage forms. The method is based on the fluorescent ion pair complex formation of the drug with eosin Y in the presence of sodium acetate-acetic acid buffer solution of pH 4.52 which is extractable in dichloromethane. The extracted complex showed fluorescence intensity at lambdaem=567 nm after excitation at 464 nm. The calibration curve was linear over the working range of 0.1-0.8 microg ml(-1). Under the optimized experimental conditions, present method is validated as per International Conference on Harmonization guidelines. The limit of detection for the developed method is 2.95 ng ml(-1). The method has been successfully applied to the determination of doxepin hydrochloride in commercial dosage forms. The results are compared with the reference spectrofluorimetric method.

Quantitative analysis of rabeprazole sodium in commercial dosage forms by spectrophotometry.

The main aim of this work is to develop and validate two spectrophotometric methods for the quantitative analysis of rabeprazole sodium in commercial dosage forms. Method A is based on the reaction of drug with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ammonium cerium(IV) nitrate in acetic acid medium at room temperature to form red-brown product which absorbs maximally at 470 nm. Method B utilizes the reaction of rabeprazole sodium with 1-chloro-2,4-dinitrobenzene (CDNB) in dimethyl sulfoxide (DMSO) at 45+/-1 degrees C to form yellow colored Meisenheimer complex. The colored complex has a characteristic band peaking at 420 nm. Under the optimized reaction conditions, proposed methods are validated as per ICH guidelines. Beer's law is obeyed in the concentration ranges of 14-140 and 7.5-165 microg ml(-1) with linear regression equations of A=6.041 x 10(-4)+1.07 x 10(-2)C and A=1.020 x 10(-3)+5.0 x 10(-3)C for methods A and B, respectively. The limits of detection for methods A and B are 1.38 and 0.75 microg ml(-1), respectively. Both methods have been applied successfully for the estimation of rabeprazole sodium in commercial dosage forms. The results are compared with the reference UV spectrophotometric method.

Optimized and validated spectrophotometric method for the determination of uranium(VI) via complexation with meloxicam.

An optimized and validated spectrophotometric method has been developed for the determination of uranyl ion in the presence of other metal ions. The method is based on the chelation of uranyl ion with meloxicam via beta-diketone moiety to produce a yellow colored complex, which absorbs maximally at 398 nm. Beer's law is obeyed in the concentration range of 5-60 microg/mL with apparent molar absorptivity and Sandell's sensitivity of 5.02 x 10(4)L/mol/cm and 0.1 microg/cm2/0.001 absorbance unit, respectively. The method has been successfully applied for the determination of uranyl ion in synthetic mixture and soil samples. Results of analysis were statistically compared with those obtained by Currah's spectrophotometric method showing acceptable recovery and precision.

Quantitation of nicorandil in pharmaceutical formulations by spectrophotometry using N-(1-naphthyl) ethylenediamine dihydrochloride as coupling agent.

A validated and sensitive spectrophotometric method is developed for the quantitation of nicorandil in pharmaceutical formulations. The method is based on the reduction of nitroxy ethyl group of nicorandil to carbonyl derivative and nitrite ion by Zn/NH4Cl. The nitrite ion undergoes diazotization with sulphanilamide in presence of HCl followed by coupling with N-(1-naphthyl) ethylenediamine dihydrochloride (NED) to form a colored product with lambda(max) at 525 nm. Under the optimized experimental condition, Beer's law is obeyed in the concentration range of 0.4-12.0 microg/ml with molar absorptivity of 1.92 x 10(4) l mol(-1) cm(-1). The statistical analysis of calibration data yields the linear regression equation: A = 6.304 x 10(-4)+9.13 x 10(-2) C with correlation coefficient of 0.9999. The limits of detection and quantification are 0.05 and 0.15 microg/ml, respectively. The results obtained by the proposed method are acceptable with average recoveries of 100.0-100.1%. The results of the proposed method are compared with those of the reference method by point and interval hypothesis tests, which showed excellent agreement and there is no significant difference in accuracy and precision of methods compared.

Kinetic spectrophotometric analysis of pantoprazole in commercial dosage forms.

A kinetic spectrophotometric method has been developed which is based on the oxidation of pantoprazole with Fe(III) in sulfuric acid medium. Fe(III) subsequently reduces to Fe(II), which is coupled with potassium ferricyanide to form Prussian blue. The reaction is followed spectrophotometrically by measuring the increase in absorbance with time (1-8 min) at 725 nm. The initial rate method is adopted for constructing the calibration graph, which is linear in the concentration range of 5-90 microg ml(-1). The regression analysis yields the calibration equation, nu = 3.467 x 10(-6) + 4.356 x 10(-5)C. The limits of detection and quantitation are 1.46 and 4.43 microg ml(-1), respectively. The proposed method was optimized and validated both statistically and through recovery studies. The experimental true bias of all samples is < +/-2.0%. The method has been successfully applied to the determination of pantoprazole in pharmaceutical preparations.

Quantitative analysis of irbesartan in commercial dosage forms by kinetic spectrophotometry.

The objective of this work is to develop a new kinetic spectrophotometric method for the determination of irbesartan in pharmaceutical formulations. The method is based on the reaction of carboxylic acid group of the oxidized irbesartan with a mixture of potassium iodate (KIO(3)) and iodide (KI) to form yellow colored triiodide ions in aqueous medium at 30+/-1 degrees C. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 352 nm. The initial-rate and fixed-time (DeltaA) methods are adopted for constructing the calibration curves, which were found to be linear over the concentration ranges of 10.0-60.0 and 7.5-60.0 microg ml(-1) respectively. The regression analysis of calibration data yielded the linear equations: rate=-2.138 x 10(-6)+1.058 x 10(-4)C and DeltaA=-3.75 x 10(-3)+3.25 x 10(-3)C for initial rate and fixed time (DeltaA) methods, respectively. The limit of detection for initial rate and fixed time methods are 0.21 and 2.40 mug ml(-1), respectively. The various activation parameters such as E(a), DeltaH++, DeltaS++ and DeltaG++ are also calculated for the reaction and found to be 70.95+/-0.43 kJ mol(-1), 68.48+/-0.21 kJ mol(-1), 16.54+/-0.24 J K(-1) mol(-1) and -4.94+/-0.07 kJ mol(-1), respectively. The proposed methods are optimized and validated as per the guidelines of International Conference on Harmonisation (U.S.A.). The point and interval hypothesis tests have been performed which indicate that there is no significant difference between the proposed methods and the reference method. The methods have been successfully applied to the determination of irbesartan in commercial dosage forms.

Kinetic spectrophotometric method for the determination of ramipril in pharmaceutical formulations.

The objective of this research was to develop a kinetic spectrophotometric method for determination of ramipril in pure form and pharmaceutical formulations. The method was based on the reaction of carboxylic acid group of the drug with a mixture of potassium iodate (KIO3) and potassium iodide (KI) in aqueous medium at room temperature. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 352 nm as a function of time. The initial-rate and fixed-time methods were adopted for constructing the calibration curves. Both the calibration curves were linear in the concentration range of 10.0-70.0 microg mL(-1). The detection limits were 0.02 microg mL(-1) and 0.15-microg mL(-1) for initial rate and fixed time methods, respectively. The proposed methods are validated statistically and through recovery studies. The point and interval hypothesis tests have been performed confirming that there is no significant difference between the proposed methods and the reference method. The experimental true bias of all samples is less than +/- 2%. The methods have been successfully applied to the determination of ramipril in tablets and capsules.

New spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations.

Two simple, sensitive and economical spectrophotometric methods were developed for the determination of nifedipine in pharmaceutical formulations. Method A is based on the reaction of the nitro group of the drug with potassium hydroxide in dimethyl sulphoxide (DMSO) medium to form a coloured product, which absorbs maximally at 430 nm. Method B uses oxidation of the drug with ammonium molybdate and subsequently reduced molybdenum blue is measured at 830 nm. Beer's law is obeyed in the concentration range of 5.0-50.0 and 2.5-45.0 microg ml(-1) with methods A and B, respectively. Both methods have been successfully applied for the assay of the drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. The reliability and the performance of the proposed methods are established by point and interval hypothesis tests and through recovery studies.

Validated kinetic spectrophotometric method for the determination of metoprolol tartrate in pharmaceutical formulations.

A kinetic spectrophotometric method has been described for the determination of metoprolol tartrate in pharmaceutical formulations. The method is based on reaction of the drug with alkaline potassium permanganate at 25+/-1 degrees C. The reaction is followed spectrophotometrically by measuring the change in absorbance at 610 nm as a function of time. The initial rate and fixed time (at 15.0 min) methods are utilized for constructing the calibration graphs to determine the concentration of the drug. Both the calibration graphs are linear in the concentration range of 1.46 x 10(-6)-8.76 x 10(-6) M (10.0-60.0 microg per 10 ml). The calibration data resulted in the linear regression equations of log (rate)=3.634+0.999 log C and A=6.300 x 10(-4)+6.491 x 10(-2) C for initial-rate and fixed time methods, respectively. The limits of quantitation for initial rate and fixed time methods are 0.04 and 0.10 microg ml(-1), respectively. The activation parameters such as E(a), DeltaH(double dagger), DeltaS(double dagger) and DeltaG(double dagger) are also evaluated for the reaction and found to be 90.73 kJ mol(-1), 88.20 kJ mol(-1), 84.54 J K(-1) mol(-1) and 63.01 kJ mol(-1), respectively. The results are validated statistically and through recovery studies. The method has been successfully applied to the determination of metoprolol tartrate in pharmaceutical formulations. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.

Validated spectrophotometric methods for the determination of amiodarone hydrochloride in commercial dosage forms using p-chloranilic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.

Two simple, sensitive and economical spectrophotometric methods have been developed for the determination of amiodarone hydrochloride in pure form and commercial dosage form. These methods (A and B) are based on the reaction of amiodarone base as n-electron donor with p-chloranilic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as pi-acceptors to give highly colored complex species which absorb maximally at 535 and 570 nm, respectively. Beer's law is obeyed in the concentration ranges 10.0 - 360.0 and 2.0 - 65.0 microg ml(-1) for methods A and B, respectively. Application of the proposed methods to commercial pharmaceutical tablets are presented.

Selective and validated spectrophotometric methods for the determination of nicorandil in pharmaceutical formulations.

Two simple and sensitive validated spectrophotometric methods have been described for the assay of nicorandil in drug formulations. Method A is based on the reaction of the drug with phloroglucinol-sulfanilic acid reagent in sulfuric acid medium to give yellow-colored product, which absorbs maximally at 425 nm. Method B uses the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) with DL- 3,4 - dihydroxyphenylalanine (DL-dopa) in the presence of nicorandil as oxidant in sulfuric acid medium to form an intensely colored product having maximum absorbance at 530 nm. Beer's law is obeyed in the concentration range 2.5 to 50.0 and 1.0 to 15.0 microg mL(-1) with methods A and B, respectively. Both methods have been successfully applied for the analysis of drug in pharmaceutical formulations. The reliability and the performance of the proposed methods are established by point and interval hypothesis and through recovery studies. The experimental true bias of all samples is smaller than +/-2%.