scholarly journals Kinetics of the Oxidation of Ascorbic Acid by the Copper (II) Ion in an Acetate Buffer Solution

1973 ◽  
Vol 46 (9) ◽  
pp. 2788-2791 ◽  
Author(s):  
Katumitu Hayakawa ◽  
Shoko Minami ◽  
Sumio Nakamura
Keyword(s):  
Ascorbic Acid ◽  
Acetate Buffer ◽  
Acetate Buffer Solution ◽  
Buffer Solution ◽  
Kinetics Of

Enzymatic hydrolysis of chitosan in acetate buffer solution

2015 ◽  
Vol 88 (4) ◽  
pp. 647-651 ◽  
Author(s):  
V. V. Chernova ◽  
A. S. Shurshina ◽  
M. V. Bazunova ◽  
E. I. Kulish
Keyword(s):  
Enzymatic Hydrolysis ◽  
Acetate Buffer ◽  
Acetate Buffer Solution ◽  
Buffer Solution ◽  
Hydrolysis Of

scholarly journals Assessment of in Vitro Comparative Dissolution Kinetics of Moxonidine Products as a Factor Potentially Determining Effectiveness of Antihypertensive Treatment

2019 ◽  
Vol 14 (6) ◽  
pp. 951-957
Author(s):  
G. V. Ramenskaya ◽  
I. E. Shokhin ◽  
N. I. Gaponova ◽  
V. R. Abdrakhmanov
Keyword(s):  
Generic Drugs ◽  
Dissolution Kinetics ◽  
Acetate Buffer Solution ◽  
Medicinal Products ◽  
Buffer Solution ◽  
Reference Drug ◽  
Similarity Factor ◽  
Kinetics Of ◽  
Comparative Dissolution

Aim. Investigation of comparative dissolution kinetics of generic medicinal products containing moxonidine versus reference drug. Material and methods. Objects of the research were film-coated tablets containing moxonidine (INN) in a dose 0.4 mg: a reference drug Physiotens® and 4 generic drugs. In vitro dissolution test of moxonidine from the study drugs was performed using comparative dissolution kinetics test (CDKT). The CDKT was performed in the media with the following pH: 1.2 (1:9 mixture of 0.1 M hydrochloric acid and water), 4.5 (acetate buffer solution, prepared as per State Pharmacopoeia, XIII), and 6.8 (phosphate buffer solution, prepared as per State Pharmacopoeia, XIII). The sampling for dissolved moxonidine was performed 5, 10, 15, 20, and 30 min after the test was started. An high performance liquid chromatography method with ultraviolet detection at 220 nm was used to assay. Results. Within 15 min more that 85% of moxonidine dissolved from the reference drug and all study drugs at pH 1.2; dissolution profiles were similar without calculation of similarity factor f2. Similarly, at pH 4.5 dissolution profiles of study drugs #2 and #3 were similar to that of the reference drug, and the similarity factor f2 was not calculated. However, in case of study drugs #1 and #4 significant differences were observed at a single time point (15 min), which suggests that their dissolution profiles are non-similar to that of the reference drug. Similarity factors f2 were calculated 17.52 and 35.30, respectively (less than 50). At pH 6.8 similarity factors f2 for all study generic drugs were also less than 50 (23.8, 49.8, 38.6, and 35.9), so their dissolution curves were non-similar to that of reference drug. Conclusion. In our study we observed difference in release in vitro of medicinal products containing moxonidines: none of the study drugs was fully similar to the reference drug in all media. The differences observed at pH 6.8 were noteworthy, where the samples had or faster kinetics (study drugs #2 and #3), or slower dissolution kinetics (test drugs #1 and #4). Observed differences in moxonidine release rate may impact absorption of active pharmaceutical ingredient into the blood following drug administration.

Collaborative Study of an Ultraviolet Method for Measuring Diquat Content in Formulations

1968 ◽  
Vol 51 (6) ◽  
pp. 1304-1305
Author(s):  
A A Carlstrom
Keyword(s):  
Systematic Error ◽  
Random Error ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Acetate Buffer ◽  
Acetate Buffer Solution ◽  
Buffer Solution ◽  
Standard Curve ◽  
Two Samples

Abstract The ultraviolet method for diquat described by Yuen, Bagness, and Myles in 1967 was collaboratively studied with formulations containing 2 lb diquat/gal. A portion of the sample is diluted with an acetate buffer solution and the absorbance is measured at 310 mμ the diquat content is obtained by reference to a standard curve prepared from known diquat concentrations. Single determinations on two samples by thirteen collaborators show an overall coefficient of variation of 2.4%. The coefficient of variation for random error is 1.0%, and for systematic error 1.6%. The method is recommended for adoption as official, first action.

Preparation and characterization of a poly-o-phenylenediamine film modified glassy carbon electrode as a H2O2 sensor

2013 ◽  
Vol 91 (11) ◽  
pp. 1077-1084 ◽  
Author(s):  
Wenying Zhai ◽  
Xiuying Tian ◽  
Yun Yan ◽  
Yuehua Xu ◽  
Yuechun Zhao ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Electrochemical Impedance ◽  
Monomer Concentration ◽  
Acetate Buffer ◽  
Acetate Buffer Solution ◽  
Carbon Electrode ◽  
Modified Glassy Carbon Electrode ◽  
Buffer Solution

A poly-o-phenylenediamine film modified glassy carbon electrode (PoPD/GC) was successfully prepared by cyclic voltammetry in acetate buffer solution. The polymerization mechanism of oPD is discussed. The impedance behavior and morphology of the PoPD membrane were characterized using cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy, respectively. It is discovered that the PoPD/GC prepared only in acetate buffer solution had dual electrocatalytic activity toward the oxidation and reduction of H2O2. The optimal buffer solution pH, scanning rate, monomer concentration, and number of scannings for film forming were 4.2, 0.05 V s−1, 6.0 mmol L−1, and 30, respectively. The linear ranges between the anodic (Δia) or cathodic (Δic) current and H2O2 concentration were 0.07−1.0 × 104 and 0.04−4.5 × 104 μmol L−1, respectively. The corresponding calibration curves were Δia (μA) = 8.03c (mmol L−1) + 6.36 (n = 18, R2 = 0.9989) and Δic (μA) = −5.52c (mmol L−1) − 0.77 (n = 18, R2 = 0.9990) with a detection limit of 0.03 and 0.02 μmol L−1 (S/N = 3), respectively. The PoPD/GC prepared in the optimal conditions showed good stability and quick response (<0.2 s) to H2O2, which was successfully applied to the determination of H2O2 in real water samples with satisfactory results.

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