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Determination of dissociation constants of some pharmaceutical compounds using derivative spectrophotometry
Author(s) -
Hewala I. I.,
ElYazbi F. A.,
Awad A.,
Wahbi A. M.
Publication year - 1992
Publication title -
journal of clinical pharmacy and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.622
H-Index - 73
eISSN - 1365-2710
pISSN - 0269-4727
DOI - 10.1111/j.1365-2710.1992.tb01298.x
Subject(s) - dissociation constant , spectrophotometry , chemistry , derivative (finance) , titration , dissociation (chemistry) , second derivative , analytical chemistry (journal) , computational chemistry , chromatography , mathematical analysis , biochemistry , receptor , mathematics , financial economics , economics
SUMMARY Derivative spectrophotometry is applied to the determination of the dissociation constants (p K a ) of some weakly dissociating compounds. The p K a value(s) can be calculated by measuring the amplitude of derivative maxima ( D ) at the selected wavelengths for the dissociated, undissociated and partially dissociated forms of the compound. A graphical technique, based on plotting the derivative spectrophotometric titration curves and interpolating p K a at D 1/2 , is also presented. Both methods are applied to pharmaceutical compounds with single and double dissociation constants. The results are in good agreement with the reported p K a values of the investigated compounds.