title: Photometric method for determination of acidity constants through integral spectra analysis.
abstract: An express method for determination of acidity constants of organic acids, based on the analysis of the integral transmittance vs. pH dependence is developed. The integral value is registered as a photocurrent of photometric device simultaneously with potentiometric titration. The proposed method allows to obtain pKa using only simple and low-cost instrumentation. The optical part of the experimental setup has been optimized through the exclusion of the monochromator device. Thus it only takes 10-15 min to obtain one pKa value with the absolute error of less than 0.15 pH units. Application limitations and reliability of the method have been tested for a series of organic acids of various nature.
authors: Saint-Petersburg State University of Technology & Design, Bolshaya Morskaya str. 18, Saint-Petersburg, 191186, Russia.
authors: Yuriy Eduardovich
authors: YE
authors: Zevatskiy
authors: Saint-Petersburg State Institute of Technology (Technical University), Moskovskiy ave., 26, Saint-Petersburg, 190013, Russia. Electronic address: daniilruzanov@mail.ru.
authors: Daniil Olegovich
authors: DO
authors: Ruzanov
authors: NovBytKhim corp, V.O. Kosaya line. 15b, Saint-Petersburg, 199026, Russia. Electronic address: samoylov@newchem.ru.
authors: Denis Vladimirovich
authors: DV
authors: Samoylov
mesh_terms: D000143:Acids / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009596:Nitrophenols / Q000032:analysis; D010783:Photometry / Q000379:methods*; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000143:Acids; D009596:Nitrophenols; C049017:3-nitrophenol
keywords: Acidity constant; Integral spectra; Photometry; Spectrometry