Kinetic Spectrophotometric Method For Determination Research Articles

Kinetic Spectrophotometric Method for Determination of Ceftriaxone in Bulk and Vials

Kinetic Spectrophotometric Method for Determination of Ceftriaxone in Bulk and Vials

Development and Validation of Kinetic Spectrophotometric Method for Determination of Venlafaxine Hydrochloride

Development and Validation of Kinetic Spectrophotometric Method for Determination of Venlafaxine Hydrochloride

New Sensitive Derivatization Methodology of Levofloxacin Antibiotic from its Dosage Formulations: Kinetic Spectrophotometric Methods for Determination

A modern validated kinetic spectrophotometric method with a novel coupling reagent has been described for the determination of levofloxacin (LEV) in pure and tablets. The method involves an oxidative-coupling reaction between LEV and 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH), in the presence of Ce(IV) in H2SO4 medium at 25±1°C, to gives greenish-blue product. The reaction is followed spectrophotometrically by measuring the increase in absorbance with time at 629 nm and then is stable for more than 2 hrs. The initial rate, rate constant, fixed absorbance and fixed time methods have been tested for constructing the calibration graphs, and are linear. The most suitable analytical methods were the initial rate and fixed time (at 20 min) methods for determination of LEV in the concentration ranges of 2.0-35.0 μg mL-1 and 0.65-35.0 μg mL-1 with LOD is 0.422 and 0.074 μg mL-1, respectively. Molar absorptivity for the method was found to be 1.40×104 L mol-1 cm-1. The activation energy (E ), activation enthalpy (ΔH ‡), activation entropy (ΔS ‡) and Gibbs free energy (ΔG ‡) are estimated for the reaction and found to be 9.84 KJ mol-1, 7.40 KJ mol-1, 177.04 JK-1 mol-1 and -44.48 KJ mol-1, respectively. The kinetic proposed methods were further applied to the determination of LEV in tablet formulations with no interfere from the excipients.

New Derivatization Methodology of 4-aminobenzoic Acid from its Dietary Supplements: Kinetic Spectrophotometric Methods for Determination

Background:A new approach describing the validation and development of an easy, new spectrophotometric and kinetic method for identification of para-aminobenzoic acid in dietary supplement has been performed. In this study, para-aminobenzoic acid was derived in a pH-controlled environment, as a new organic compound 4(4-Benzophenylazo)pyrogallol, by incorporating diazotized para-aminobenzoic acid with pyrogallol.Objective:The determination of para-aminobenzoic acid was conducted by the fixed time and initial rate techniques. These approaches were based on the reaction of the compound containing paraaminobenzoic acid, 4(4-Benzophenylazo)pyrogallol, with Ag(I) to form colored product with a maximum absorbance at 468nm. Both of these techniques were adopted for constructing the calibration curves and examined for their suitability for the quantitation of para-aminobenzoic acid in dietary supplement.Methods:The determination process was established, using initial rate and fixed time kinetic spectrophotometric methods.Results:4(4-Benzophenylazo)pyrogallol was characterized using proton-nuclear magnetic resonance, Fourier-transform infrared, differential scanning calorimetry and thermogravimetric thermal methods, gas chromatography–mass techniques, and solvatochromic behavior in solvents with different polarities was also examined.Conclusion:For the first time, para-aminobenzoic acid was well determined by incorporating it as an organic solid compound, 4(4-Benzophenylazo)pyrogallol, through coupling pyrogallol with diazotized para-aminobenzoic acid in regulated pH medium, ranging between 5.0 to 6.0. The existence of common excipients in the dietary supplement did not produce any significant interference. F- and ttest data analysis were used for statistical comparison of the suggested techniques with that of reference method, demonstrating excellent agreement with no significant difference in the associated precision and accuracy.

Kinetic Spectrophotometric Method for 4-nitrophenol Determination in Drinking Water

This paper describes a rapid, highly sensitive and simple kinetic spectrophotometric method for determination of p-nitrophenol (p-NP) based on its activating effect on sulfanilic acid oxidation by hydrogen peroxide in basic media in the presence of Co2+ as catalyst. Coloration of sulfanilic acid is used to monitor the reaction spectrophotometrically at 368 nm. p-Nitrophenol can be determined in the ranges of 40‒200 and 200‒400 ng/mL under optimal conditions. The detection limit of the method according to 3σ criteria is 8 ng/mL. The RSD is 4.8‒0.8% for concentration interval 40‒200 ng/mL. The kinetic parameters of the reaction are reported, and the rate equations are suggested. The developed procedure was successfully applied to the rapid determination of p-NP in water samples using solid phase extraction for phenol preconcentration and removing interferences. The HPLC method was used as comparative method to verify results.

Analytical application of the reaction system disulphonated hydroquinone-hydrogen peroxide for the kinetic spectrophotometric determination of iron traces in acidic media

A simple, rapid, sensitive and selective kinetic spectrophotometric method for determination of Fe(III) traces was elaborated in this paper. It is based on the catalytic effect of Fe(III) ions on oxidation of potassium salt of disulphonated hydroquinone (K2S2Hy) by hydrogen peroxide in acidic media, at a constant ionic strength. At the working temperature of 20?C and the wavelength of 450.0 nm, optimal conditions for determination of iron were found so that iron (III) can be determined by the proposed method in the concentration range of 1.87 to 18.7 ng cm-3. Corresponding RSD values were determined to be in the range 4.22 to 10.33 %. The limit of detection (LOD) calculated in two ways was found to be 1.07 ng cm-3 i.e. 1.11 ng cm-3 Fe(III). In order to assess the selectivity of the method effects of different ions on the reaction rate were also determined. It was found that presence of oxalates and citrates in the w/w ratio to Fe(III) 1:1 under selected experimental conditions interferes with determination of iron. Then the method was applied for determination of Fe(III) traces in white radish juice. The results agreed well with those obtained by atomic absorption spectrometry.

Development of a kinetic spectrophotometric method for insecticide diflubenzuron determination in water and baby food samples

A kinetic spectrophotometric method for determining residues of insecticide diflubenzuron 1(4-chlorphenyl)-3-(2,6-diflubenzoyl)urea (DFB) has been developed and validated. Kinetic method was based on the inhibitory effect of DFB on the oxidation reaction of sulfanilic acid (SA) by hydrogen peroxide in the presence of Co2+ ions in a phosphate buffer, which was monitored at 370 nm. DFB can be measured in the concentration interval 0.102 ? 3.40 ?g mL-1 and 3.40 ? 23.80 ?g mL-1. The detection and quantification limits of the method were calculated according to the 3? criteria and found to be 0.077 ?g mL-1 and 0.254 ?g Ml-1, respectively. The relative standard deviations for five replicate determinations of 0.102, 1.70 and 3.40 ?g mL-1 DFB were 2.08, 1.22 and 1.21 %, respectively, for the first concentration interval, and the recovery percentage values were from 94.12 to 97.35 %. HPLC method was used as a parallel method to verify results of the kinetic method. The kinetic method was successfully applied to determine diflubenzuron concentrations in spiked water and baby food samples after solid phase extraction of the samples. The F and t values at 95% confidence level are lower than the theoretical ones, confirming agreement of the developed and the HPLC method.

Kinetic Spectrophotometric Method for Determination of Vanadium in Syrian Oil Using 1,5-Diphenylcarbazide Reagent

New, sensitive, accurate and inexpensive kinetic spectrophotometric method was developed and validated for the determination of V(V) in crude oil and its heavy product. The method is based on the formation of colored complex between V(V) and 1, 5-diphenylcarbazide (DPCI). The method involves the reaction of V(V) with DPCI in presence of buffer solution of pH 6.8 to form colored complex with λmax at 530 nm. The fixed time method (2000 Sec) was adopted for constructing the calibration curve. The linearity range was found to be (2-12) mg/L. The correlation coefficient was 0.9999 and the limit of detection was found to be 0.349 mg/L. The method is feasible with the calibration equations obtained, which makes this method more applicable. Statistical treatment of the experimental results indicates that the method is precise, selective and accurate. The method was successfully applied for determination of V(V) in Syrian crude oil and its heavy product.

Kinetic Spectrophotometric Method for Determination of Vanadium in Syrian Oil Using 1,5-Diphenylcarbazide Reagent

New, sensitive, accurate and inexpensive kinetic spectrophotometric method was developed and validated for the determination of V(V) in crude oil and its heavy product. The method is based on the formation of colored complex between V(V) and 1, 5-diphenylcarbazide (DPCI). The method involves the reaction of V(V) with DPCI in presence of buffer solution of pH 6.8 to form colored complex with λmax at 530 nm. The fixed time method (2000 Sec) was adopted for constructing the calibration curve. The linearity range was found to be (2-12) mg/L. The correlation coefficient was 0.9999 and the limit of detection was found to be 0.349 mg/L. The method is feasible with the calibration equations obtained, which makes this method more applicable. Statistical treatment of the experimental results indicates that the method is precise, selective and accurate. The method was successfully applied for determination of V(V) in Syrian crude oil and its heavy product.

Development and validation of kinetic spectrophotometric method for herbicide bromfenoxim determination

A kinetic spectrophotometric method for determining the residues of herbicide bromofenoxim (BrFX) has been developed and validated. The proposed method is based on the inhibitory effect of BrFX on the oxidation of sulfanilic acid (SA) by hydrogen peroxide in the presence of Cu(II) ion, which was monitored at 370 nm. The variables affecting the rate of the reaction were investigated and the optimum conditions were established. BrFX can be measured in the range of 0.041 - 0.46 ?g/ml and 0.46 - 13.86 ?g/ml. The detection limit of the method with 3? criteria is 0.0077 ?g/ml. The relative standard deviations for five replicate determinations of 0.041, 0.24 and 0.46 ?g/ml BrFX are 3.0, 5.32 and 2.85%, respectively. This method can be successfully used to determine BrFX concentration in baby juice samples. The HPLC method is used to verify the results. The results obtained for the same samples by the two methods are quite comparable.

New Kinetic Spectrophotometric Method for Determination of Folic Acid in Pharmaceutical Formulations

A simple and sensitive kinetic spectrophotometric method has been developed for the determination of folic acid (FA) in bulk and pharmaceutical Formulations. The method is based on the oxidation of FA by 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 at λmax 725 nm. The rate data and fixed time methods were adopted for constructing the calibration curves. The linearity range was found to be 1–20 μg mL-1 for each method. The correlation coefficient was 0.9978 and 0.9993, and LOD was found to be 0.91 and 0.09 μg mL-1 for rate data and fixed time methods, respectively. The proposed method has been successfully applied to the determination of FA in formulations with no interference from the excipients. Statical comparison of the results shows that there is no significant difference between the proposed and pharmacopoeial methods

New Kinetic Spectrophotometric Method for Determination of Folic Acid in Pharmaceutical Formulations

A simple and sensitive kinetic spectrophotometric method has been developed for the determination of folic acid (FA) in bulk and pharmaceutical Formulations. The method is based on the oxidation of FA by 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 at λmax 725 nm. The rate data and fixed time methods were adopted for constructing the calibration curves. The linearity range was found to be 1–20 μg mL-1 for each method. The correlation coefficient was 0.9978 and 0.9993, and LOD was found to be 0.91 and 0.09 μg mL-1 for rate data and fixed time methods, respectively. The proposed method has been successfully applied to the determination of FA in formulations with no interference from the excipients. Statical comparison of the results shows that there is no significant difference between the proposed and pharmacopoeial methods

Determination of trace amount of formaldehyde base on a bromate-Malachite Green system

A novel catalytic kinetic spectrophotometric method for determination of trace amount of formaldehyde (FA) has been established, based on catalytic effect of trace amount of FA on the oxidation of Malachite Green (MG) by potassium bromate in presence of sulfuric acid medium, and was reported for the first time. The method was monitored by measuring the decrease in absorbance of MG at 617nm and allowed a precise determination of FA in the range of 0.003–0.08μgmL−1, with a limit of detection down to 1ngmL−1. The relative standard deviation of 10 replicate measurements was 1.63%. The method developed was approved to be sensitive, selective and accurate, and adopted to determinate free FA in samples directly with good accuracy and reproducibility.

Kinetic spectrophotometric method for the determination of some fourth generation fluoroquinolones in bulk and in pharmaceutical formulations

A kinetic spectrophotometric method for accurate and sensitive determination of gemifloxacin (GMFX) and gatifloxacin (GTFX) has been described. The method is based on the reaction of the studied drugs with potassium permanganate in the presence of sodium hydroxide to form a water-soluble green product which shows maximum absorbance at 604nm. The determination of GMFX and GTFX drugs by rate constant, fixed-concentration, and fixed time methods was feasible with the calibration equations obtained but the fixed time method had been found to be more applicable. The concentration of the selected drugs is calculated using the calibration equation for the fixed time method. The absorbance–concentration plot is linear over the range of 4–36μgmL−1 and 4–40μgmL−1 with correlation coefficient of 0.9998 and 0.9991, for GMFX and GTFX, respectively. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The intra- and inter-day RSD values indicated the ruggedness of the method. The proposed method has been successfully applied to pharmaceutical formulations of each drug. Statistical comparison of the results with a well established reported method showed excellent agreement and proved that there is no significant difference in the accuracy and precision.

New Kinetic Spectrophotometric Method for Determination of Atorvastatin in Pure and Pharmaceutical Dosage Forms

New, accurate, sensitive and reliable kinetic spectrophotometric method for the assay of atorvastatin calcium (AVS) in pure form and pharmaceutical formulations has been developed. The method involves the oxidative coupling reaction of AVS with 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) in the presence of Ce(IV) in an acidic medium to form colored product with lambdamax at 566 nm. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 566 nm as a function of time. The initial rate and fixed time methods were adopted for constructing the calibration curves. The linearity range was found to be 2.0-20.0 μg/mL for initial rate and fixed time methods. The limit of detection for initial rate and fixed time methods is 0.093 and 0.064 μg/mL, respectively. Molar absorptivity for the method was found to be 3.36×104 L/ mol cm. Statistical treatment of the experimental results indicates that the methods are precise and accurate. Both methods have been applied successfully for the estimation of pravastatin sodium in commercial dosage forms with no interference from the excipients. The results are compared with the pharmacopoeial method.

Kinetic spectrophotometric method for determination of amlodipine besylate in its pharmaceutical tablets

A simple and sensitive kinetic spectrophotometric method has been developed and validated for determination of amlodipine besylate (AML). The method was based on the condensation reaction of AML with 7-chloro-4-nitro-2,1,3-benzoxadiazole in an alkaline buffer (pH 8.6) producing a highly colored product. The color development was monitored spectrophometrically at the maximum absorption λmax 470nm. The factors affecting the reaction were studied and the conditions were optimized. The stoichiometry of the reaction was determined, and the reaction pathway was postulated. Moreover, both the activation energy and the specific rate constant (at 70°C) of the reaction were found to be 6.74kcalmole−1 and 3.58s−1, respectively. The initial rate and fixed time methods were utilized for constructing the calibration graphs for the determination of AML concentration. Under the optimum reaction conditions, the limits of detection and quantification were 0.35 and 1.05μg/mL, respectively. The precision of the method was satisfactory; the relative standard deviations were 0.85–1.76%. The proposed method was successfully applied to the analysis of AML in its pure form and tablets with good accuracy; the recovery percentages ranged from 99.55±1.69% to 100.65±1.48%. The results were compared with that of the reported method.

Determination of lisinopril in pharmaceuticals by a kinetic spectrophotometric method

A kinetic spectrophotometric method for determination of lisinopril in pharmaceuticals has been developed. The method is based on activator action of lisinopril on Cu(II) ions catalysing the oxidation of nile blue A with hydrogen peroxide in borate buffer (pH 9.3). A decrease of the absorbance was recorded at 635 nm for 5 min at 25?C. The linearity was established applying the tangent method within the concentration range of lisinopril from 0.8-6.4 ?g mL-1, the detection and quantification limits being 0.158 ?g mL-1 and 0.480 ?g mL-1, respectively. The method has been successfully applied in three brands of tablets containing lisinopril alone or in combination with hydrochlorothiazide.

Catalytic and kinetic spectrophotometric method for determination of vanadium(V) by 2,3,4-trihydroxyacetophenonephenylhydrazone

A new catalytic and kinetic spectrophotometric method for the determination of vanadium(V) was studied using 2,3,4-trihydroxyacetophenonephenylhydrazone (THAPPH) as an analytical reagent. The present method was developed on the catalytic effect of vanadium on oxidation of THAPPH by hydrogen peroxide in hydrochloric acid–potassium chloride buffer (pH=2.8) at the 20th minute. The metal ion has formed 1:2 (M:L) complex with THAPPH. Beer’s law was obeyed in the range 20–120ng/mL of V(V) at λmax 390nm. The sensitivity of the method was calculated in terms of molar absorptivity (1.999×105 Lmol−1cm−1) and Sandell’s sensitivity (0.000254μgcm−2), shows that this method is more sensitive. The standard deviation (0.0022), relative standard deviation (0.56%), confidence limit (±0.0015) and standard error (0.0007) revealed that the developed method has more precision and accuracy. The stability constant was calculated with the help of Asmu’s (9.411×10−11) and Edmond’s & Birnbaum’s (9.504×10−11) methods at room temperature. The interfering effect of various cations and anions was also studied. The present method was successfully applied for the determination of vanadium(V) in environmental and alloy samples. The method’s validity was checked by comparing the results obtained with atomic-absorption spectrophotometry and also by evaluation of results using F-test.

A simple kinetic spectrophotometric method for determination of Tizanidine hydrochloride in pharmaceutical preparations

A simple, reliable, and sensitive kinetic method for the accurate and sensitive determination of Tizanidine hydrochloride (TIZ) is described. The method is based on the alkaline oxidation of TIZ with potassium permanganate at a fixed time of 25min. The formed manganate ion is measured at 610nm. The concentration of TIZ is calculated using the calibration equation for the fixed time method. Beer’s law is obeyed in the range of 2–13μgml−1, and the results are validated statistically and checked through recovery studies. This method has been successfully applied for the determination of the studied drug in commercial dosage forms. Statistical comparisons of the results with the reference methods show excellent agreement and indicate no significant difference in accuracy and precision.

Kinetic spectrophotometric method for trace determination of thiocyanate based on its inhibitory effect

A kinetic spectrophotometric method for the determination of thiocyanate, based on its inhibitory effect on silver(I) catalyzed substitution of cyanide ion, by phenylhydrazine in hexacyanoferrate(II) is described. Thiocyanate ions form strong complexes with silver(I) catalyst which is used as the basis for its determination at trace level. The progress of reaction was monitored, spectrophotometrically, at 488 nm ( λ max of [Fe(CN) 5PhNHNH 2] 3−, complex) under the optimum reaction conditions at: 2.5 × 10 −3 M [Fe(CN) 6] 4−, 1.0 × 10 −3 M [PhNHNH 2], 8.0 × 10 −7 M [Ag +], pH 2.8 ± 0.02, ionic strength ( μ) 0.02 M (KNO 3) and temperature 30 ± 0.1 °C. A linear relationship obtained between absorbance (measured at 488 nm at different times) and inhibitor concentration, under specified conditions, has been used for the determination of [thiocyanate] in the range of 0.8–8.0 × 10 −8 M with a detection limit of 2 × 10 −9 M. The standard deviation and percentage error have been calculated and reported with each datum. A most plausible mechanistic scheme has been proposed for the reaction. The values of equilibrium constants for complex formation between catalyst–inhibitor ( K CI), catalyst–substrate ( K s) and Michaelis–Menten constant ( K m) have been computed from the kinetic data. The influence of possible interference by major cations and anions on the determination of thiocyanate and their limits has been investigated.