Beginner with RNA extraction

[Dimple Win]

      OD reading 280 should tell u the amt of protein contamination in 
your sample. To lower the chances of contamination, you should take 
only 2/3 to 1/4 of the upper aqueous phase after the centrifuge in 
Braun for 20 min. To see the phases clearly, i usually quick-spin the 
tubes right before transfering aqueous phase. 

	Draw the upper phase in slowly so you won't disturb the protein layer 
when transfering. This should help also in avoiding contamination of 
proteins. 

Good luck.
Dimple Ann. (u.c.davis)

On 21 Jun 1996, Edouard Lauzier wrote:

> Sorry for the silly question but...
> 
> 
> I know that the 260/280 ration tells u the purity of your sample ( 2.0 for RNA )
> Lately I'm unable to get over 1.5
> I understand that the 260 value tells you the amount of nucleic acid you have...
> But what the 280 means ? How can I loer it to get a higher ratio ?  My
> point being if phenol ( 270 ) or proteins (230 ) absorb at those
> wavelenghts, the fact of getting rid of them should not affect the
> ratio... 
> 
> Thanks in advance for your help...
> 
> p.s. I use the Chomczynski and Sacchi ( 1986 ) method...
> -- 
> Edouard Lauzier, B.Sc.                           elauzier at fse.ulaval.ca
> Physical Activity Science Laboratory
> (Laval University)  G1K 7P4
> CANADA
> 
> 
> 
>