scholarly journals Determination of quercetin in pharmaceutical formulations via its reaction with potassium-titanyloxalate: Determination of the stability constants of the quercetin-titanyloxalato complex

2005 ◽  
Vol 70 (5) ◽  
pp. 753-763 ◽  
Author(s):  
Vesna Kuntic ◽  
Natasa Pejic ◽  
Svetlana Micic ◽  
Vladana Vukojevic ◽  
Zorica Vujic ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Quantitative Determination ◽  
Stability Constants ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Pharmaceutical Dosage Forms ◽  
Different Temperatures ◽  
The Stability ◽  
Second Procedure

Asimple, rapid and accurate procedure for the quantitative determination of quercetin in its pure form and in formulations has been developed. The method is based on the spectrophotometric determination of a complex formed between quercetin and potassium titanyloxalate in 50 % ethanolic solutions. To characterize the quercetin titanyloxalato complex, the stability constants of the complex were determinated potentiometrically and spectrophotometrically at different temperatures (T = 26.0oC, 34oC and 39.0oC), as well as at different ionic strengths (I = 5.0x10-4 mol dm-3, 3.0x10-2 mol dm-3 and 6.0x10-2 mol dm-3) and the thermodynamic parameters were calculated. As quercetin is usually conjugated to vitamin C in pharmaceutical formulations, two procedures for the quantitative determination of quercetin by this complexing reaction were tested - both in the absence and presence of ascorbic acid. In both procedures, the Beer law was obeyed over the same concentration range of quercetin, i.e., 0.85 ?g mL-1 - 16.9 ?g mL-1. In the first procedure in the absence of ascorbic acid the molar absorptivity coefficient of the quercetin-titanyloxalate complex is a=2.49 x 104 mol-1 dm3 cm-1, Sandells sensitivity of the method is S = 1.35 x 10-2 ?g cm-2 and the detection limit is d = 0.67 ?g mL-1. Whereas, in the presence of ascorbic acid (second procedure) a = 3.04 x 104 mol-1 dm3 cm-1, S = 1.11 x 10-2 ?g mL-1. The proposed method was verified for the determination of quercetin in pharmaceutical dosage forms. .

scholarly journals Indirect spectrophotometric Indirect spectrophotometric determination of chlordiazepoxide in pharmaceutical formulations via oxidative coupling reaction with phenothiazine

2018 ◽  
pp. 7-14
Author(s):  
Hind Hadi ◽  
Mariam Jamal
Keyword(s):  
Oxidative Coupling ◽  
Coupling Reaction ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Dosage Forms ◽  
Calibration Plot ◽  
Pharmaceutical Dosage Forms ◽  
Oxidative Coupling Reaction ◽  
Formed Product

Abstract A sensitive, precise and reliable indirect spectrophotometric method for the determination of chlordiazepoxide (CDE) in pure and pharmaceutical dosage forms is described. The method is based on oxidative coupling reaction between amino group resulting from acidic decomposition of CDE with phenothiazine in the presence of sodium periodate to produce an intense green soluble dye that is stable and shows a maximum absorption at 602 nm. The calibration plot indicates that Beer’s law is obeyed over the concentration range of 0.1?50 µg/mL, with a molar absorptivity of 1×104 L/mol cm and correlation coefficient of 0.9994.All the conditions that affecting on the stability and sensitivity of the formed product were studied and optimized and the suggested method was effectively applied for the determination of CDE in commercial dosage forms.

scholarly journals Sensitive Spectrophotometric Methods for the Determination of Ascorbic Acid

2008 ◽  
Vol 5 (1) ◽  
pp. 10-15 ◽  
Author(s):  
H. D. Revanasiddappa ◽  
M. A. Veena
Keyword(s):  
Ascorbic Acid ◽  
Acid Medium ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Spectrophotometric Methods ◽  
Maximum Absorbance ◽  
Hydrochloric Acid Medium ◽  
Subsequent Determination ◽  
Sulphuric Acid Medium

Two simple and sensitive spectrophotometric methods (A and B) have been described for the determination of ascorbic acid. Method A is based on the oxidation of ascorbic acid (AA) by known excess of Se(IV) in hydrochloric acid medium and subsequent determination of unreacted Se(IV) by reacting it with iodide in the same acid medium to liberate iodine, which react with starch to form a stable blue coloured iodine-starch complex, which shows maximum absorbance at 590 nm. Method B is based on the oxidation of ascorbic acid (AA) by known excess of Cr(VI) in sulphuric acid medium and the determination of unreacted Cr(VI) with diphenyl carbazide (DPC) under the same acidic medium to produce a stable red-violet coloured species, which shows a maximum absorbance at 550 nm. The reacted oxidants (in methods A and B) correspond to the AA content. The apparent molar absorptivity values are found to be 1.627×104and 1.641×104L mol-1cm-1for methods A and B, respectively. The proposed methods are simple, sensitive and suitable for the routine analysis of AA in pharmaceutical formulations and in real samples.

scholarly journals Spectrophotometric determination of sotalol in tablets

2018 ◽  
pp. 49-55
Author(s):  
Y. M. Zhuk ◽  
S. O. Vasyuk
Keyword(s):  
Quantitative Determination ◽  
Room Temperature ◽  
Cost Effective ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Pharmaceutical Drugs ◽  
Analysis Method ◽  
Highly Sensitive ◽  
Colored Product

In this investigation a visible spectrophotometric method for the determination of sotalol based on the absorbance of colored product of the reaction between sotalol hydrochloride and bromcresol purple in acetone medium at 399 nm measurement was developed. The optimal conditions for the quantitative determination of sotalol hydrochloride in the content of pharmaceutical drugs were established. The stoichiometric relationship coefficients between sotalol hydrochloride and bromcresol purple were determined. The validation of the worked out procedure on such validated characteristics as linearity, precision, accuracy and robustness was carried out. The aim. To develop a highly sensitive, easy to use, cost-effective and valid method for quantitative determination of sotalol hydrochloride in dosage forms. The analysis method. Visible spectrophotometry. The analytical parameters such as molar absorptivity, Beer’s law limits and Sandell’s sensitivity values were calculated. The developed methods give the result with repeatability sufficient for dependable determination the investigated substance in pharmaceutical formulations. Accuracy established by analyte addition technique. Determined factors that influence on the absorbance value: reagent quantity and timing stability. Sample solutions stable during 30 min. Addition to sample solution ± 10% bromcresol purple solution is not change the absorbance value. Established that reaction between sotalol hydrochloride and bromcresol purple proceeds in acetone medium at room temperature. Molar absorption coefficient is 2,62∙103.

scholarly journals A Simple and Cost-Effective TLC-Densitometric Method for the Quantitative Determination of Acetylsalicylic Acid and Ascorbic Acid in Combined Effervescent Tablets

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3115 ◽  
Author(s):  
Alina Pyka-Pająk ◽  
Małgorzata Dołowy ◽  
Wioletta Parys ◽  
Katarzyna Bober ◽  
Grażyna Janikowska
Keyword(s):  
Ascorbic Acid ◽  
Quantitative Determination ◽  
Acetylsalicylic Acid ◽  
High Performance ◽  
Limit Of Detection ◽  
Volume Ratio ◽  
Cost Effective ◽  
Pharmaceutical Formulations ◽  
Limit Of Quantification

A new, simple, and cost-effective TLC-densitometric method has been established for the simultaneous quantitative determination of acetylsalicylic acid and ascorbic acid in combined effervescent tablets. Separation was performed on aluminum silica gel 60F254 plates using chloroform-ethanol-glacial acid at a volume ratio of 5:4:0.03 as the mobile phase. UV densitometry was performed in absorbance mode at 200 nm and 268 nm for acetylsalicylic acid and ascorbic acid, respectively. The presented method was validated as per ICH guidelines by specificity, linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. Method validations indicate a good sensitivity with a low value of LOD and LOQ of both examined active substances. The linearity range was found to be 1.50–9.00 μg/spot and 1.50–13.50 μg/spot for acetylsalicylic and ascorbic acid, respectively. A coefficient of variation that was less than 3% confirms the satisfactory accuracy and precision of the proposed method. The results of the assay of combined tablet formulation equal 97.1% and 101.6% in relation to the label claim that acetylsalicylic acid and ascorbic acid fulfill pharmacopoeial requirements. The developed TLC-densitometric method can be suitable for the routine simultaneous analysis of acetylsalicylic acid and ascorbic acid in combined pharmaceutical formulations. The proposed TLC-densitometry may be an alternative method to the modern high-performance liquid chromatography in the quality control of above-mentioned substances, and it can be applied when HPLC or GC is not affordable in the laboratory.

scholarly journals Spectrophotometric Methods for the Assay of Fluvoxamine Using Chromogenic Reagents

2010 ◽  
Vol 7 (4) ◽  
pp. 1539-1545
Author(s):  
V. Annapurna ◽  
G. Jyothi ◽  
V. Nagalakshmi ◽  
B. B. V. Sailaja
Keyword(s):  
Ascorbic Acid ◽  
Regression Analysis ◽  
Standard Error ◽  
Oxidative Coupling ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Method Of Least Squares ◽  
Spectrophotometric Methods ◽  
Uv Visible

Simple, accurate and reproducible UV-Visible spectrophotometric methods were established for the assay of FXA based on the oxidative coupling and condensation reactions. Condensation and coupling of the FXA with Ninhydrin-Ascorbic acid is proposed in method A. Method B includes complexation of FXA with cobalt thiocyanate. The ligating property of FXA with sodium nitro prusside is incorporated in method C. The optical characteristics such as Beers law limits, molar absorptivity and Sandell’s sensitivity for the methods (A-C) are given. Regression analysis using the method of least squares was made to evaluate the slope(b), intercept(a) and correlation coefficient (r) and standard error of estimation (Se) for each system. Determination of FXA in bulk form and in pharmaceutical formulations were also incorporated.

scholarly journals Colorimetric Determination of Paracetamol Using 9-Chloroacridine Reagent: Application to Pharmaceutical Formulations

2020 ◽  
Vol 63 (2) ◽  
pp. 71-78
Author(s):  
Firas Hassan Awad
Keyword(s):  
Standard Deviation ◽  
Pharmaceutical Formulations ◽  
Extraction Process ◽  
Molar Absorptivity ◽  
Colorimetric Determination ◽  
Average Recovery ◽  
Relative Standard ◽  
Recovery Percentage ◽  
The Stability

This paper aims to develop a simple, sensitive and accurate spectrophotometric method for quantitative determination of paracetamol in aqueous medium. The method is based on the reaction between the hydrolyzed paracetamol and 9-chloroacridine reagent (9-CA). The spectra of the product show maximum absorption at 436 nm. Beer's law is obeyed in the concentration range of 0.25-11 µg/mL with molar absorptivity value 5.3x103 L/mol/cm. The average recovery percentage (Rec%) is 99.27% and relative standard deviation (RSD) is :: 2.82%. In addition, the stability constant has been determined and the reaction mechanism is proposed. The method has been applied successfully for the assay of paracetamol in pharmaceutical formulations. It is found that the method does not require extraction process and it agree well with British pharmacopeia.    

scholarly journals Development and application of spectrophotometric method for quantitative determination of Metronidazole in pure and tablet formulations

2016 ◽  
Vol 2 (1) ◽  
pp. 28 ◽  
Author(s):  
Zeeshan Masood ◽  
Muhammad Tayyab Ansari ◽  
Sharjeel Adnan ◽  
Muhammad Asad ◽  
Muhammad Farooq ◽  
...  
Keyword(s):  
Quantitative Determination ◽  
Spectrophotometric Method ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Dosage Forms ◽  
Nitrite Ion ◽  
Colored Complex ◽  
Accuracy And Precision ◽  
Significant Difference

A rapid, simple and sensitive spectrophotometric method has been developed for the determination of metronidazole in pharmaceutical pure and dosage forms. The method depends on alkaline hydrolysis of metronidazole releases the nitro group as nitrite ion and yielded nitrite ions can be used to give a colored complex that absorbs maximally at 505 nm. Beer’s law is obeyed in the concentration ranges 9-100 mg/ml with molar absorptivity of 1.14 ×103 L mole-1 cm-1. The proposed method is precise, accurate and specific for the quantitative determination of drug in bulk and dosage forms. The results of analysis of commercial formulations and the recovery study of metronidazole suggested that there is no interference from any excipients, which are present in pharmaceutical formulations of metronidazole. Statistical comparison of the results was performed with regard to accuracy and precision using student’s t-test and F-ratio at 95% confidence level. There is no significant difference between the reported and proposed methods with regard to accuracy and precision.

scholarly journals Sensitive Spectrophotometric Determination of Lamotrigine in Bulk Drug and Pharmaceutical Formulations using Bromocresol Green

2018 ◽  
Vol 35 (1) ◽  
pp. 55
Author(s):  
N. Rajendraprasad ◽  
K. Basavaiah ◽  
K. B. Vinay
Keyword(s):  
Potassium Hydroxide ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Ion Pair ◽  
Bromocresol Green ◽  
Spectrophotometric Methods ◽  
Base Form ◽  
Bulk Drug ◽  
The Stability

Two new, simple, rapid and reproducible spectrophotometric methods have been developed for the determination of lamotrigine (LMT) both in pure form and in its tablets. The first method (method A) is based on the formation of a colored ion-pair complex (1:1 drug/dye) of LMT with bromocresol green (BCG) at pH 5.02±0.01 and extraction of the complex into dichloromethane followed by the measurement of the yellow ion-pair complex at 410 nm. In the second (method B), the drug-dye ion-pair complex was dissolved in ethanolic potassium hydroxide and the resulting base form of the dye was measured at 620 nm. Beer’s law was obeyed in the concentration range of 1.5-15 μg mL-1 and 0.5-5.0 μg mL-1 for method A and method B, respectively, and the  = corresponding molar absorptivity values are 1.6932 x 104 and 3.748 x 104L mol-1cm-1. The Sandell sensitivity values are 0.0151 and 0.0068 μg cm-2 for method A and method B, respectively. The stoichiometry of the ion-pair complex formed between the dug and dye (1:1) was determined by Job’s continuous variations method and the stability constant of the complex was also calculated. The proposed methods were applied successfully for the determination of drug in commercial tablets.

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