the following temperature program to the sample and the
reference: cooling from 20 to À10
C at 10
C/min, holding
at À10
C for 1 min, and heating from À10 to 150
C at
10
C/min. Plot the first derivative of the heat flow recorded
during the heating scan, and identify the Tg. To eliminate
interference from enthalpic relaxation, an additional cycle can
be performed: heating from 20
C to a temperature few
degrees higher than Tg at 10
C/min, cooling to À10
C at
10
C/min, holding at À10
C for 1 min, and heating from
À10 to 150
C at 10
C/min.
4. Measure the water content using the Karl Fisher method.
Determination of the water content of methanol:
(a) Fill five vials with 2 mL of dry methanol.
(b) Take ~0.5 mL of methanol with the syringe in a vial, rinse
the syringe with methanol, take ~0.8 mL of methanol in
the same vial (m blank ), and inject this quantity in the Karl
Fisher titration vessel, note the measured quantity of
water (x blank ).
(c) Repeat this procedure for the four remaining vials.
Determination of the water content of the freeze-dried
sample:
Fig. 5 Evolution of process variables with time during the freezing and primary drying steps, including fluid
(shelf) temperature, cold trap temperature, product temperature in different locations (Th1–Th5), and chamber
pressure (Pirani gauge and capacitance manometer)
Physical Properties and Freeze-Drying of Bacteria
715
reference: cooling from 20 to À10
C at 10
C/min, holding
at À10
C for 1 min, and heating from À10 to 150
C at
10
C/min. Plot the first derivative of the heat flow recorded
during the heating scan, and identify the Tg. To eliminate
interference from enthalpic relaxation, an additional cycle can
be performed: heating from 20
C to a temperature few
degrees higher than Tg at 10
C/min, cooling to À10
C at
10
C/min, holding at À10
C for 1 min, and heating from
À10 to 150
C at 10
C/min.
4. Measure the water content using the Karl Fisher method.
Determination of the water content of methanol:
(a) Fill five vials with 2 mL of dry methanol.
(b) Take ~0.5 mL of methanol with the syringe in a vial, rinse
the syringe with methanol, take ~0.8 mL of methanol in
the same vial (m blank ), and inject this quantity in the Karl
Fisher titration vessel, note the measured quantity of
water (x blank ).
(c) Repeat this procedure for the four remaining vials.
Determination of the water content of the freeze-dried
sample:
Fig. 5 Evolution of process variables with time during the freezing and primary drying steps, including fluid
(shelf) temperature, cold trap temperature, product temperature in different locations (Th1–Th5), and chamber
pressure (Pirani gauge and capacitance manometer)
Physical Properties and Freeze-Drying of Bacteria
715