Freeze-thaw-method

**Rambo21** · 05-08-2009, 04:38 PM

I want to use IGF-lr3 in bac water over 12 days/100mcg . Does it going to be stable if I use the freeze thaw method ? And if not , how long max does it stay stable in the fritch in bac water ? probely it depend on the source ?

Thanks.

**hulk1747** · 05-08-2009, 05:57 PM

I put 2 ml bw and .3 ml white distilled vinager in a 1mg bottle then I preload all my syringes and freeze. they defrost very quickley so it works good.

**Slide** · 05-08-2009, 06:24 PM

lion says that just BW is fine, any word on that?

**hulk1747** · 05-09-2009, 08:23 AM

I dont know, I was always told that you have to have atleast a little acid in there to preserve it even if freezing. Thats what my supplier said and he hasnt done me wrong over the last 8 years, he knows his stuff.

**thefunkybuddha** · 05-09-2009, 09:17 AM

Originally Posted by hulk1747

I dont know, I was always told that you have to have atleast a little acid in there to preserve it even if freezing. Thats what my supplier said and he hasnt done me wrong over the last 8 years, he knows his stuff.

Many things have changed over 8 years...especially in the biotech area. I know virtually all proteins degrade when frozen. To what extent may be arguable. But I can tell you this...how quickly it takes to freeze the product has a huge impact on how much protein is destroyed by the freezing process. ie. you really need a flash freezer to do it properly. Secondly...what type of freezer are you keeping it in? All freezers that you would have in your home cycle in temperature...its how freezers are 'frost free'. So during this cycle the temperature intentionally fluctuates...it may at times be above freezing...the things in your freezer may not melt but there is a lot of water activity. This is what causes 'freezer burn'. A constant thawing and refreezing...as a result the ice crystals get larger and larger...and destroy your product. The freezers that frozen proteins are kept at within the industry are at a constant -70F...no fluctuations...these are specific freezers for this purpose. I know you guys have many sources that you trust....this is just my 2 cents being a chemical engineering in the biotech industry.