BRADFORD reagent - (Apr/04/2006 )

Hi all,

I did a Bradford reagent, but its color was dark blue instead of light brown (the right color)!!
I really don't know what I did wrong. The protocol that I followed is:

Bradford reagent:
Dissolve 100 mg Coomassie Brilliant Blue G-250 in 50 ml 95% ethanol, add 100 ml 85% (w/v) phosphoric acid. Dilute to 1 liter when the dye has completely dissolved, and filter through Whatman #1 paper just before use.

I diluted to 1 liter with destiled water, is it right?
or...
Can be pH the problem?

Please help me.
Thanks,

Carol

your glassware (plasticware?) may be contaminated.

What's wrong with buying pre-made Bradford's reagent?

100 mg of Comassie
50 ml of 95% ethanol
100 ml of phosphoric acid (85%)
+ 50 ml ddH20

That is 5 x Bradford reagent

I sometimes get a lightly greenish brown color that gets fully brown after adding a bit more phosphoric acid. If yours is dark blue it could be because of detergents in plastic/glassware.