Two Different Strategies Based on Three‐Way Analysis Models of UV Spectroscopic and Spectrochromatographic Measurements to Quantify the Acidity Constant of Acetylsalicylic Acid

Abstract

A comparative study to quantify acid dissociation constant (pKa) of acetylsalicylic acid by applying the parallel factor analysis (PARAFAC) to three‐way data arrays of UV spectroscopic and spectrochromatographic measurements was presented. In data recording and data collection stages, the spectrochromatograms of 20 μg/mL acetylsalicylic acid in different mobile phases having seven different pH levels were recorded, and a cubic data set was created with time x wavelength x pH dimensions. UV spectra of the analyte in the concentration range of 10–30 μg/mL and in seven different pH media were recorded and arranged as a three‐way array with dimensions, wavelength x concentration x pH. To estimate the pKa by two different chemometric strategies, the cubic data sets were decomposed into trilinear components, which allowed to predict the pKa in the pH profiles. In practice, the three‐way analysis‐based UV spectroscopic and spectrochromatographic methods didn't include a titration procedure and had a second‐order advantage over traditional pKa determination methods. As a result, this investigation on the rapid and accurate estimation of the acidity constant of acetylsalicylic acid provided alternative and practical ways to determine the pKa of active pharmaceutical ingredients in the future.