The novel ninhydrin-based deep eutectic solvents (DESs) were synthesized from choline chloride (ChCl) and tetrabutylammonium hydrogen sulfate (TBAHS) as hydrogen bond acceptors (HBAs) in a combination with ninhydrin as a hydrogen bond donor (HBD). In this work, the new HBA and HBD respectively including TBAHS and ninhydrin for the first time were presented. The obtained deep eutectic solvents were further characterized at different temperatures with the results of density, sound velocity, viscosity, electrical conductivity, refractive index, and surface tension data along with the 1H and 13C NMR, and FTIR analysis in order to confirm their purities, chemical structure, and occurrence interaction between the HBAs and HBD which formed the deep eutectic mixtures. The temperature dependences of their thermophysical properties were explored and correlated with simple linear models Jacobson and Arrhenius equation. The isothermal expansion (α), excess molar volume (VE), molar volumes (Vm), free volumes (fm), intermolecular free length (Lf), isentropic compressibility (β), molar conductivity (Λm), and molar refractions (Rm) values were calculated from the measured density, speed of sound, conductivity, and refractive index data. The synthesized DESs were applied as solvent and indicator reagent for quantitative and qualitative determination of alanine. Also, the DESs displayed ability with high efficiency for replacement of organic solvents which are used in the amino acid detection processes.
