Comments Regarding “Volumetric, Acoustic, Viscometric Properties, and Solute–Solvent Interactions of Metformin Hydrochloride in Aqueous Solution of Polyethylene Glycol (PEG 4000) at Different Temperatures ( T = 288.15–318.15 K)”

A polemic is given regarding both the experimental and calculated volumetric properties reported by Arabgol and Pazuki. The authors’ calculated apparent molal volumes for metformin hydrochloride dissolved in both water and in binary aqueous + PEG 4000 solvent mixtures are not consistent with the measured solution densities. Moreover, the apparent molal volume for metformin hydrochloride in water, calculated from the experimental densities, is negative and is significantly different from the positive values given in four previously published papers.