Multiplexing Through Vial Impedance Spectroscopy (TVIS) with Comparative Pressure Measurement. Poster presentation at ISL-FD 9th International Conference 2-6th September, 2019, Ghent, Belgium

Two IgG formulations, one with 5% sucrose and the other with 5% Mannitol:Sucrose (ratio 4:1) both in 20mM Histidiine 0.01% Tween 20 pH 6.5, were freeze dried in a Telstar freeze dryer equipped with Pirani and Baratron sensors and a Sciospec® five-channel through vial impedance spectroscopy (TVIS) system. The TVIS parameter C'(100kHz) (i.e. the real part electrical capacitance measured at 100 kHz) is sensitive to the amount of ice in the vial. By following the recovery of its time profile during primary drying, it was possible to determine the primary drying endpoint. The TVIS endpoint of the sucrose edge vial occurred well before the onset of the Pirani endpoint suggesting that Pirani was more sensitive to the core vials. The TVIS endpoint in the core vials also occurred somewhere close to the midpoint of the Pirani endpoint suggesting that other core vials were still in primary drying.