@conference{
author = "Mrđinac, Jelena Ž. and Marković, Olivera S. and Pešić, Miloš P. and Verbić, Tatjana",
year = "2022",
abstract = "The ionization constant (usually expressed in logarithmic form, pKa) is important
physicochemical parameter which is used to characterize the acid-base chemistry of a
compound. Since most drugs contain one or more ionizable functional groups,
knowledge of pKa values is necessary in drug research. The most common techniques
used for pKa determination are potentiometry and spectrophotometry. Potentiometry is
a method of choice when ionization processes are overlapping, as in such case it is not
possible to obtain the absorption spectrum of each species present in solution. The aim
of this work was the comparative analysis of pKa determination using potentiometry and
spectrophotometry for model compounds with overlapping ionization processes: 3-
aminobenzoic acid, 1,3,5-benzenetricarboxylic acid and tyrosine. The potentiometric
titrations were performed with pSOL Model 3 instrument (pION) equipped with pS
software package for titration data analysis.1 Avdeef–Bucher four–parameter equation
was used for electrode standardization.2 To overcome the above-mentioned limitation of
spectrophotometry, the alternative approach was applied in this study. The new
aminocaproate phosphate buffer (containing phosphoric and ε-aminocaproic acids) was
used for the solutions preparation of the model compounds in pH range 1 – 12. This
buffer has numerous advantages like UV-transparency, resistance to pH changes upon
standing for several days, useful buffer capacity and constant ionic strength in the wide
range of pH values. Absorption spectra were recorded according to specific procedure
which was carefully designed to avoid systematic errors. Collected absorption spectra
will be used for the development of the algorithm for the spectral deconvolution (using
MATLAB). Such software can be very useful tool in the drug research, especially for
the analysis of the compounds which pKa values cannot be determined by potentiometry.",
publisher = "Belgrade : Serbian Chemical Society, Belgrade : Serbian Young Chemists’ Club",
journal = "8th Conference of Young Chemists of Serbia, Belgrade, Serbia, 29th October, 2022. In: Book of Abstracts",
title = "Comparative analysis of ionization constants determination using spectrophotometry and potentiometry: 3- aminobenzoic acid, 1,3,5-benzenetricarboxylic acid and tyrosine",
pages = "42-42",
url = "https://hdl.handle.net/21.15107/rcub_cherry_5939"
}
