Acidity and pH of DES-like mixtures and the possibilities of their determination

•Assessment of acidity or alkalinity is a fundamental aspect of characterization of DES-like mixtures.•The review summarizes the measurement of acidity/alkalinity by different methods.•Methodologies include pH measurement, Hammett acidity function, pKa values, application of indicator dyes, conductivity assessment, computational modeling, and acid-base titration. Evaluating the acidity or alkalinity of deep eutectic solvents-like mixtures (DES-like mixtures) stands as a fundamental facet in their characterization. This review paper provides a comprehensive summary of the various approaches employed to measure acidity or alkalinity within these mixtures. The methodologies encompass a wide spectrum of techniques, spanning from traditional pH measurements and Hammett acidity function to more advanced methods such as determining pKa values, utilizing indicator dyes, conducting conductivity assessments, employing computational modeling, and applying acid-base titration. This diverse range of methods not only enhances our understanding of these mixtures but also paves the way for their tailored manipulation, promising innovative applications in diverse fields.