Change of colour in cell culture media...? - (Jul/29/2010 )

Hi all,
I am using Hams F12 media for my cells, which i make it in house from hams F12 powder. My query is regarding the colour change in my media. i make a couple of bottles evrery time i make some media, which intially has an reddish orange colour. once i start using my media it turns to pure pink in a week but the bottle that i havent yet opened remains the same orange reddish colour...? i was wondering if any body could help me understand the reason behind it. i would also like to add that this change in colour doesn't effect the growth of my cells but i am just curious and thought it would be interesting to know..!!

thank you all in advance.
k.sagi

I also see this quite a lot with my RPMI 1640 basal media. This has Phenol Red in it as an idicator of pH. I think once you open the bottles and start using the media, exposing it to the atmosphere and reducing the volume causes a slight change in pH. Mine seems to begin at a pink-red colour and gets pinker (increase in pH/more alkaline). Any additives you add to your media may also influence the pH, and if the lifespan of any of these additives is short they may 'go off' and thus affect the pH.

Mammalian cells grow best at roughly neutral pHs and as they grow and produce waste they acidify the media turning it a more orange-yellow colour. I think my media is ok, even if it does shift colour a little. If you see particles/solids in your media it may have become contaminated.

You may also want to make sure you keep your media at 4*C and minimise the amount of time you have to warm it for cell culture and minimise the time the actual media is exposed to the atmosphere. That is all I can think of! I don't think that it's too alarming that the media gets a little pinker...

http://en.wikipedia.org/wiki/Phenol_red

The colour change is due to pH change from the medium equilibrating with CO2 in the atmosphere.