I think that option #2 is the intent.
 
>>> "B. Prabhakar Pandian" <[log in to unmask]> 10/22/09 4:54 PM >>> 
Hello Mike,
                       I know that from the mathematical stand point 
what you are saying is correct, but the contention is more from what 10% 
actually means. Is it to add 10% of the original volume of
serum (option # 1) to the media or to make sure that the final 
concentration is 10% (option # 2).

Thanks,

Mike Tighe wrote:
> If total volume is 550mls (500ml media and 50mls serum you will have  9.1%  serum. Not 10% but probably enough to keep most cells happy
>
> Mike
>  
>   
>>>> "B. Prabhakar Pandian" <[log in to unmask]> 10/22/09 3:10 PM >>> 
>>>>         
> Hello,
>              In our laboratory there has been recent debates on the cell 
> media preparation. The point of contention is the presence of serum in 
> media.
> When a media mentions supplemented with 10% serum, which of the 
> following is correct for a 500ml media bottle.
>
> 1. Add 50ml of serum to the media bottle (total volume is 550ml)
>
> 2. Remove 50ml of media and then add 50ml of serum (total volume is 500ml).
>
> Any information on the right usage will be great.
>
> Thanks,
>
> -  Bala
>
>
>   


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