SDS-PAGE for purity

[D.K.]

 drabena at hotmail.com wrote:
>I am currently running SDS-PAGE's to calculate the "percent area" of a single
> protein.  Can anyone tell me how to run this assay to determine the percent
> purity?  
>
>http://www.biowww.net/index.php/forum/forumlist/1/

There is no truly good way to run such an assay. Conventional 
scanning/integration of total lane gives absolutely wrong results. 
The best way I know is to i) determine total protein concentration 
in your sample, ii) load in parallel a series of known amounts
of [some standard] protein, iii) compare intensities, deduce amount
of the given band in your sample and thus deduce % of total. 
With some experience, simple eyeballing estimates come as 
close to reality as any "quantitative" method (that is, still 
inaccurate). 

DK