A method for determining whether reconstitution of a solution in a container is completed comprises the steps of: selecting a predetermined amount of a solid substance and a predetermined amount of a liquid solvent from which the reconstituted solution is to be prepared, preparing a solution by solving the predetermined amount of the solid substance in the predetermined amount of the liquid solvent, measuring the impedance (Z) or the resistance (R) of the solution, determining whether the change of the measured impedance (Z) or the resistance (R) within a measuring time interval of a predetermined duration is below a defined threshold, and determining that reconstitution of the solution is completed when the change of the measured impedance (Z) is below the defined threshold.