As soon is sample is inserted in the chamber at -80 C, bubbles starts forming and restricts the drying process. What could be done to avoid this.
This is just my personal speculations on the matter:
1. Should your sample is liquid, bubble may have arisen from the entrapped tiny air or gas bubbles during the mixing and merged back as an impact of molecular constrictions due to the thermal shocked of freezing.
2. May try to overcome it by: 1). do more careful or more gentle mixing during sample preparation and, use laminar flow mixing, if possible, to prevent from turbulence and eddy diffusion during the sample mixing; 2) degassed you samples by exposing it to vacuum pressure before you inserted into freeze dryer chamber.
Can you provide a little bit more information, please?
Do you insert the dry sample, RT, into the chamber, which is at -80°C, or do you pre-cool it? If so, how does it cool? Do you apply vacuum immediately? Do the bubbles form at atmospheric pressure?
What is the sample chemistry?
If you freeze your sample first, say in liquid nitrogen, it is likely that the bubbles are boiling nitrogen.
This is just my personal speculations on the matter:
1. Should your sample is liquid, bubble may have arisen from the entrapped tiny air or gas bubbles during the mixing and merged back as an impact of molecular constrictions due to the thermal shocked of freezing.
2. May try to overcome it by: 1). do more careful or more gentle mixing during sample preparation and, use laminar flow mixing, if possible, to prevent from turbulence and eddy diffusion during the sample mixing; 2) degassed you samples by exposing it to vacuum pressure before you inserted into freeze dryer chamber.
Hi..
If the product is not properly frozen before drying, it produces bubbling when exposed to vacuum condition, due to the presence of air pockets in the products.
Complete frozen state of product may prevent the formation of bubbling.
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