Peroxidase-based spectrophotometric methods for the determination of ascorbic acid, norepinephrine, epinephrine, dopamine and levodopa

1997 ◽  
Vol 357 (3) ◽  
pp. 261-267 ◽  
Author(s):  
Min Zhu ◽  
Xuemei Huang ◽  
Jie Li ◽  
Hanxi Shen
Keyword(s):  
Ascorbic Acid ◽  
Spectrophotometric Methods

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 Comparative Study of Novel Ratio Spectra and Isoabsorptive Point Based Spectrophotometric Methods: Application on a Binary Mixture of Ascorbic Acid and Rutin

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Hany W. Darwish ◽  
Ahmed H. Bakheit ◽  
Ibrahim A. Naguib
Keyword(s):  
Ascorbic Acid ◽  
Binary Mixture ◽  
High Performance ◽  
Pharmaceutical Tablets ◽  
Spectrophotometric Methods ◽  
First Derivative ◽  
Ratio Difference ◽  
Mean Centering ◽  
Assay Conditions

This paper presents novel methods for spectrophotometric determination of ascorbic acid (AA) in presence of rutin (RU) (coformulated drug) in their combined pharmaceutical formulation. The seven methods are ratio difference (RD), isoabsorptive_RD (Iso_RD), amplitude summation (A_Sum), isoabsorptive point, first derivative of the ratio spectra (1DD), mean centering (MCN), and ratio subtraction (RS). On the other hand, RU was determined directly by measuring the absorbance at 358 nm in addition to the two novel Iso_RD and A_Sum methods. The work introduced in this paper aims to compare these different methods, showing the advantages for each and making a comparison of analysis results. The calibration curve is linear over the concentration range of 4–50 μg/mL for AA and RU. The results show the high performance of proposed methods for the analysis of the binary mixture. The optimum assay conditions were established and the proposed methods were successfully applied for the assay of the two drugs in laboratory prepared mixtures and combined pharmaceutical tablets with excellent recoveries. No interference was observed from common pharmaceutical additives.

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.

Semimicro Method for Determination of Serum Uric Acid Using EDTA—Hydrazine

1968 ◽  
Vol 14 (8) ◽  
pp. 764-775 ◽  
Author(s):  
C P Patel
Keyword(s):  
Ascorbic Acid ◽  
Uric Acid ◽  
Serum Uric Acid ◽  
Phosphotungstic Acid ◽  
Sodium Salicylate ◽  
Sodium Tungstate ◽  
Hydrazine Sulfate ◽  
Spectrophotometric Methods ◽  
Automated Procedures

Abstract A semimicro method is described for the determination of uric acid by manual and automated procedures. Serum uric acid reduces phosphotungstic acid in an alkaline medium of EDTA sodium tungstate and hydrazine sulfate, the latter being used as a color intensifier. The use of sodium tungstate eliminates the development of interfering turbidity encountered with other alkalizing reagents. This method requires only 0.2 ml. of serum. The presence of ascorbic acid, sodium salicylate, cysteine, and/or glucose does not interfere. A linear relationship is obtained upon comparing this method with the sodium carbonate and the differential ultraviolet spectrophotometric methods.

Validated Univariateand Multivariate Spectrophotometric Methods for Determination of Paracetamol, Ascorbic Acid and Pseudoephedrine Hydrochloride

2016 ◽  
Vol 6 (6) ◽  
pp. 706-717 ◽  
Author(s):  
Nourrudin. W. Ali ◽  
Nada. S. Abdelwahab ◽  
Maha. M. Abdelrahman ◽  
Badr A. EL-Zeiny ◽  
Salwa. I. Tohamy
Keyword(s):  
Ascorbic Acid ◽  
Spectrophotometric Methods
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