Good morning. I am running an FTS durastop / duradry lyophilizer here
in our fermentation pilot plant for the Saskatchewan Research Council up
here in Canada. We are working on a live E coli vaccine, so the
material to be freeze-dried is a TFF concentrated microbial culture
diluted 1:1 with a Dextrin/Sucrose FD medium. The amounts to be
lyophilized are 5 mls in 20ml vials. Problem is , we are running the
vials in a tray which is sealed inside a large paper autoclave bag to
maintain sterility during the lyophilisation.
I can only seem to get two trays (bagged) to within 4 or 5 % of the
target moisture content. The vials seem nice and dry, uniform in color
as well, but the cakes inside the vials do tend to have a bit of a hill
in the middle of the cake on the top surface and the moisture readings
as performed in a vac oven are coming out at 10% instead of the required
4%.
My programmed cycle is -30 for 60 min / atmos. Then -20 for 60 min /
2000mtorr. Then -10 for 120 min / 880 mtorr. Then 0C for 120min /
0mtorr. The secondary cycle kicks in to warm the vials to a 20C
endpoint at 0-10 mtorr. The entire cycle takes about 18 hours. The
problem is, I can not seem to get the moisture down the last required
5-6%. I have been playing with the cycles but everything I adjust seems
to make things worse not better. I am afraid I will run out of material
to test with before I get the cycle worked out. If you have any
suggestions they would be much appreciated.
Have a great day.
Robert D Ashton
Ag-Biotech, Fermentation
Saskatchewan Research Council
125, 15 Innovation BLVD
Saskatoon, Sk., Canada
S7N 2X8
ashton At src.sk.ca
(306) 933-5103
(cell) 222-8493
"SRC provides Smart Science Solutions"
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