AUTOMATION OF VAPOR-PRESSURE OSMOMETRY MEASUREMENTS

A program has been developed for the control of Vapour Pressure Osmometry (VPO) measurements. The output signal of a Vapour Pressure Osmometer is read by an A/D converter card installed in one of the expansion slots of a PC microcomputer. The stability of the measurements is checked by analysing the first derivative of the smoothed signals, which is calculated in real time. Sets of repeated measurements are carried out under the supervision of a computer program as a check for their reproducibility. When the set is ended the program calculates the average and its standard deviation. The program is particularly valuable for evaluating VPO measurements for solution equilibria studies. This interfacing strategy may be applied to any kind of technique in which the time-stability of the signals is the basis for defining measurement stability. The automated VPO has other advantages, including low cost and time saving.