Making Water-Saturated Phenol - (Dec/07/2006 )
This is a pretty silly question but how do I make water-saturated phenol from phenol crystals? I know I should just add phenol to the water until it no longer goes into solution but I want a ballpark ratio of phenol to water. The fume hood in our lab is filled with equipment so I can't move in both the stirplate and weigh machine at the same time. Going back and forth carrying phenol crystals to add to the water makes me feel uncomfortable for myself and others.
I haven't been able to find a consistent protocol online (one said to add 10g phenol to every 1ml water while another said the ratio should be 1:1). Calling up the manufacturer (Fisher) was no help either.
Thank you much.
Excess water will float to the top, so the easiest way is to add water in excess to a bottle containing phenol. Note that for most molecular biology applications you should likely be controlling the pH of the phenol, which means using buffer rather than water, and changing the buffer until the phenol reaches the desired pH (7.5 or 8.0 for DNA work, 4.5 for RNA work). Hydroquinone is often added as an antioxidant.
I used to make saturated phenol (acidic and alkaline) by the protocol u mentioned above but this time the phenol and tris were mixed together without separation into 2 phases.
What do u suggest
I think that this means that you have not yet achieved an excess of buffer, add more buffer until two phases are visible then it is saturated...
Too dilute a solution will make a single water domnated phase. I should have mentioned that things go more smoothly if you melt the phenol first. Are you sure this is how you want to do this? Sigma, e.g., sells pre-made buffered phenol.
This is what I was going to ask. It would be cheaper and less hazardous (and importantly easier) to buy the finished reagent in the first place.
thank u all, Finally I prepared the saturated phenol and it was separated successfully after using a new bottle of stock phenol.
It seems that I was using old phenol