The protonation/deprotonation equilibrium of thymidine and azidothymidine studied by UV spectra and multivariate curve resolution
| Authors | |
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| Year of publication | 2004 |
| Type | Article in Proceedings |
| Conference | sborník- XLVII Zjazd PTchem i SITPChem Wroclaw 2004 |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | Thymidine; Azidothymidine; UV spectra;Multivariate Curve Resolution |
| Description | The aim of our work was to study of protonation/deprotonation equilibrium of AZT and AZU in aqueous solutions with different concentrations of NaCl by using UV spectra connected with chemometrics. Calibration and correct function of pH meter (electrode) was performed by acido-basic potenciometric titration (HCl and NaOH), of which parameters were calculated by means of GranLs method. Correct way how to determine ionization constants was verified using thymidine and uridine for which the pKa value was known. The absorption spectra were measured from 240 to 320 nm at temperature 25C and various ionic strength from 0.05M to 0.25M. The absorption maxima of thymidine and AZT are very close and have values of 267 and 266.5 nm for pH 8, respectively. The wavelength of maxima of uridine and AZU were identical 262nm, but the absorbance of AZU has hypochromical shift. Firstly, from non-smoothed spectra the system of matrices (É, A.U., pH) was made (Fig. a), that were the input data for Multivariate Curve Resolution (MCR, Matlab) [6,7]. The data were processed on a Pentium PC computer using software package MATLAB (version 6) from Mathworks Inc. (Natick, MA) routines codes are freely available at URL: www.ub.es/gesq/mcr/mcr.htm). |
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