retinol, cholecalciferol, vitamin B12

David J. Austin, Ph.D. austin at SLSIRIS.HARVARD.EDU
Fri Sep 23 06:48:59 EST 1994

On 22 Sep 1994, Victor Jimenez G. wrote:

> I have a question concerning 3 vitamins (retinol, cholecalciferol and 
> vit. B12).  According to the labels of these reagents, they are light 
> and air sensitive and they are stored under argon.  I do not have a 
> facility to store in argon, so I asked the people at Sigma Technical 
> Service, and they told me that we can store them in dry nitrogen, and 
> that it is not recommended to store frozen solutions of these 
> products.  

  I am not sure what you mean by facility to store argon.  Storing under 
argon means a sealed bottle in which all of the AIR inside the bottle has 
been replaced with ARGON.  Therefore all you need to do is find someone 
willing to let you use their argon tank.  NITROGEN works the same, but 
argon is better since it is heavier than air and forms a nice BLANKET 
over the chemical.  We seal our bottles with parafilm, but this is 
probably more for peace of mind, rather than practical good.  What you 
are worried about here is oxygen that will oxidize the vitamins (no 
doubt) or light that will also adversly affect them (ie retinal all trans 
to 13-cis in bacteriorhodopsin etc).
  As far as temperature, we store compounds of UNKNOWN stability at -20.  
In this case it is best to follow KNOWN guideline and store at rt.
  Good handling tips are work quickly, always preserve the purity of the 
stock, never leave the lid off the bottle, and never add back to the 
stock -- even when you have overweighed.  Always replace the atmosphere 
over the chemical every time you open the bottle.  Yes, even with argon.


David J. Austin, Ph.D.      
Department of Chemistry     austin at
Harvard University
Cambridge, MA 02138

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