SDS buffer - (Sep/23/2008 )

Please help, I need to prepare an SDS-sample buffer without B-MeSH.

Here is what I need:
Tris-HCl (.25M,pH6.8)
SDS (8%)
Glycerol (40%)
Bromophenol blue (.02%)

Here is what I have:
Tris-HCl (.5M,pH6.8)
SDS (20%)
Glycerol (100%)

Thank you!!

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Well, first you need Bromophenol blue , you didn't say you even have that.

But, you also need a more concentrated Tris-HCl to use in order to make your needed solution. With a .5M stock you will need to use 50% of your final volume to get to .25M.

So if you were making 100mL
you would need
50mL of .5M Tris-HCl
40mL 100% glycerol
40mL (20%) SDS
that's 130mL right there to make 100mL

either the SDS or, more feasibly, the Tris-HCl stock must be more concentrated.

**disclaimer - I have made math errors in the past, I could be wrong (Once when I was four years old I added wrong, ONCE)

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I 2nd the idea to have a much more concentrated Tris stock. Tris easily dissolves in water at 1.5M and beyond but getting SDS beyond 20% concentration is time-consuming at best and will need to heat it considerably to dissolve it.... and even then it might precipitate out when it cools down to room temperature. Our Lab had a heater problem a year ago and our 10% SDS was even precipitating out... and it was only 16C in-doors.

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