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oai:ojs.www.eurjchem.com:article/901 2014-03-31T01:48:51Z eurjchem:ART driver

New chemometric strategies in the spectrophotometric determination of pKa Amador-Hernandez, Judith Rojas-Hernandez, Alberto Colunga-Urbina, Edith Madai De La Garza-Rodriguez, Iliana Margarita Velazquez-Manzanares, Miguel Medina-Vallejo, Luis Felipe pKa PLS PCR MCR-ALS Spectrophotometry Chemometric strategies In this work, principal component regression and partial least squares regression were used for the estimation of acid dissociation constants through UV-Vis spectrophotometric measurements, considering five well-known acid-base indicators as well as two herbicides as analytes. In each case, an acid-base titration was carried out. Then, the multivariate calibration model was constructed with a few absorption spectra of the series at extreme pH values, to which values of the dissociation fraction (α) of 1 or 0 were assigned, in the case of HA or Aspecies. After that, the prediction step consisted in the estimation of α for the rest of the series. Then, distribution diagrams were built up with α vs pH, to find α = 0.5 where pH = pKa. The results were compared with those obtained through multivariate curve resolution-alternating least squares and program stability quotients from absorbance data (SQUAD), which showed an excellent correspondence. Atlanta Publishing House LLC 2014-03-31 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.eurjchem.com/index.php/eurjchem/article/view/901 10.5155/eurjchem.5.1.1-5.901 European Journal of Chemistry; Vol. 5 No. 1 (2014): March 2014; 1-5 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/901/PDF_901