Determining osmotic pressure of drug solutions by air humidity in equilibrium method

AbstractObjective: To establish a new osmotic pressure measuring method with a wide measuring range.Method: The osmotic pressure of drug solutions is determined by measuring the relative air humidity in equilibrium with the solution. The freezing point osmometry is used as a control.Results: The data obtained by the proposed method are comparable to those by the control method, and the measuring range of the proposed method is significantly wider than that of the control method.Conclusion: The proposed method is performed in an isothermal and equilibrium state, so it overcomes the defects of the freezing point and dew point osmometries which result from the heterothermal process in the measurement, and therefore is not limited to diluted solutions.