Spectrophotometric determination of association equilibrium constants of certain phenol substitution derivatives with triethylamine

1966 ◽  
Vol 5 (4) ◽  
pp. 354-358
Author(s):  
F. D. Mamedov ◽  
M. A. Salimov
Keyword(s):  
Spectrophotometric Determination ◽  
Equilibrium Constants ◽  
Association Equilibrium

Infrared Characterization and Determination of Self-Association Equilibrium Constants for Methacrylic Acid Copolymers

2000 ◽  
Vol 39 (2) ◽  
pp. 197-223 ◽  
Author(s):  
CHRISTOPHER S. CLEVELAND ◽  
STEPHEN P. FEARNLEY ◽  
YUHONG HU ◽  
MARK E. WAGMAN ◽  
PAUL C. PAINTER ◽  
...  
Keyword(s):  
Methacrylic Acid ◽  
Equilibrium Constants ◽  
Methacrylic Acid Copolymers ◽  
Self Association ◽  
Association Equilibrium

Spectrophotometric study of complexation equilibria and of a method for the determination of Fe(III) ions with 4-(2-pyridylazo)resorcinol and 4-(2-thiazolylazo)resorcinol

1979 ◽  
Vol 44 (2) ◽  
pp. 374-392 ◽  
Author(s):  
Ellena Russeva ◽  
Vlastimil Kubáň ◽  
Lumír Sommer
Keyword(s):  
Stability Constants ◽  
Spectrophotometric Determination ◽  
Equilibrium Constants ◽  
Spectrophotometric Study ◽  
Component Concentration ◽  
Optimum Conditions ◽  
Ferric Ions ◽  
Absorption Coefficients ◽  
Basic Parameters

The composition, molar absorption, coefficients, equilibrium constants and stability constants for the MLH, ML, M(LH)2 and ML2 complexes have been determined graphically using slope-intercept transformations and numerically from the absorbance-pH curves and from the absorbance dependence on the component concentration, using the PRCEK III and SPEKTFOT programs, or from the continuous variation plots using the JOBCON program. The optimum conditions were found for a spectrophotometric determination of ferric ions with TAR and PAR reagents in pure solutions. The basic parameters of the analytical curves were evaluated using the STAT program.

Study of reaction of 5-hydroxy-6-(2-hydroxy-5-sulfophenylazo)benzo(a)-phenazine with vanadates in the presence of Septonex

1980 ◽  
Vol 45 (3) ◽  
pp. 819-825 ◽  
Author(s):  
Nguyen Truong Son ◽  
Milan Kotouček ◽  
Eduard Ružička
Keyword(s):  
Aqueous Medium ◽  
Spectrophotometric Determination ◽  
Acidic Medium ◽  
Equilibrium Constants ◽  
Medium Ph

Reaction of 5-hydroxy-6-(2-hydroxy-5-sulfophenylazo)benzo(a)phenazine with vanadates in aqueous medium was studied in the presence and in the absence of the tenside Septonex. In acidic medium (pH 2-6), the complex VO2L is formed in both cases. The equilibrium constants for the equilibria studied were calculated and a procedure was suggested for spectrophotometric determination of vanadium.

scholarly journals Protolytic equilibria in homogeneous and heterogeneous systems of ketoconazole and its direct spectrophotometric determination in tablets

2005 ◽  
Vol 70 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Mirjana Vojic ◽  
Gordana Popovic ◽  
Dusan Sladic ◽  
Lidija Pfendt
Keyword(s):  
Ionic Strength ◽  
Spectrophotometric Determination ◽  
Spectrophotometric Method ◽  
Equilibrium Constants ◽  
Heterogeneous Systems ◽  
Water Systems ◽  
Acidity Constant ◽  
Acid Base ◽  
Protolytic Equilibria

The acid-base equilibria of a diprotic, slightly hydrosoluble base ketoconazole were studied in homogeneous and heterogeneous water systems. The determinations were performed at 25?C at a constant ionic strength of M(NaCl). The acidity constant Ka1 was determined by potentiometric (pKa1 3.20) and spectrophotometric (pKa1 3.26) methods. A pKa2 constant of 6.10 was obtained based on the equilibrium constants pKs0 4.84 and pKs1 -1.26, determined in a heterogeneous ketoconazole system. The obtained values of the constants served to calculate the solubility and the distribution of the equilibrium forms of ketoconazole as a function of pH. On the basis of the distribution of the equilibrium forms of ketoconazole, a spectrophotometric method for the determination of its content in commercial tablets was developed. The determinations were performed at 225 nm in 0.1 M HCl. The method is simple and rapid and enables the direct spectrophotometric determination of the content of ketoconazole without previous isolation.

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