Document Detail


A study of pH-dependent photodegradation of amiloride by a multivariate curve resolution approach to combined kinetic and acid-base titration UV data.
MedLine Citation:
PMID:  23024976     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Amiloride photostability at different pH values was studied in depth by applying Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) to the UV spectrophotometric data from drug solutions exposed to stressing irradiation. Resolution of all degradation photoproducts was possible by simultaneous spectrophotometric analysis of kinetic photodegradation and acid-base titration experiments. Amiloride photodegradation showed to be strongly dependent on pH. Two hard modelling constraints were sequentially used in MCR-ALS for the unambiguous resolution of all the species involved in the photodegradation process. An amiloride acid-base system was defined by using the equilibrium constraint, and the photodegradation pathway was modelled taking into account the kinetic constraint. The simultaneous analysis of photodegradation and titration experiments revealed the presence of eight different species, which were differently distributed according to pH and time. Concentration profiles of all the species as well as their pure spectra were resolved and kinetic rate constants were estimated. The values of rate constants changed with pH and under alkaline conditions the degradation pathway and photoproducts also changed. These results were compared to those obtained by LC-MS analysis from drug photodegradation experiments. MS analysis allowed the identification of up to five species and showed the simultaneous presence of more than one acid-base equilibrium.
Authors:
Michele De Luca; Giuseppina Ioele; Sílvia Mas; Romà Tauler; Gaetano Ragno
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-1
Journal Detail:
Title:  The Analyst     Volume:  -     ISSN:  1364-5528     ISO Abbreviation:  Analyst     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372652     Medline TA:  Analyst     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Pharmaceutical Sciences, University of Calabria, Via P. Bucci, 87036 Rende, Italy. michele.deluca@unical.it.
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