Influence of fructose on the diffusion of potassium hydrogen phosphate in aqueous solutions at 25 °C

• Diffusion coefficients of aqueous systems of fructose and potassium hydrogen phosphate measured with Lobo’s cell.
• Influence of the fructose on the diffusion of potassium hydrogen phosphate.
• Interactions between of hydrogen phosphate anion and fructose.

Diffusion coefficients have been measured at 25 °C for potassium hydrogen phosphate (K2HPO4, 0.101 mol kg−1) in aqueous solutions containing various concentrations of fructose from (0.001 to 0.101) mol kg−1, using a conductimetric cell (the Lobo cell) coupled to an automatic data acquisition system. Significant effects of fructose were observed on the diffusion of K2HPO4 in these mixtures, which are attributed to the interaction between HPO42− anion (or other protonated forms) and fructose. Support for this comes from 1H and 13C NMR spectroscopy, which are compatible with binding between the anomeric forms of d-fructose and the HPO42− anion.