tris buffer - tris base or hcl (May/22/2008 )
Are tris base and tris hcl interchangeable in a protocol that requires tris buffered saline if you adjust the ph? My protocol recommends Trizma from Sigma but I only have Tris base??? Help!
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Edit for a quick answer:
but the formula weights are different???
Trizma is Tris-HCl. And Tris base is without HCl, highly alkaline. that is why. With Trizma, you will have to add less HCl when you make the soln at your required pH. So taht would compensate for it.
Thanks for your help!
trizma is sigma's name for tris(hydroxymethyl)aminomethane (fisher calls it tham).
it comes in various forms (base, hcl, acetate, etc).
tris (trizma) base has a fw of 121.14. if it is not this then it is not tris base.
tris (trizma) hcl has a fw of 157.60.
the useful pH range for tris buffer is approximately 7-9.
to make tris buffer you would take tris base and adjust the pH with hcl then bring to final volume.
you could take tris-hcl and adjust with naoh or koh (depending on the salt you want with your buffer).
the best way to prepare the buffer is to make equimolar stocks of tris base and tris-hcl, mix them until you get the pH you want and not have to worry about the final volume. then dilute the adjusted stock to the working concentration (with any additions that you may require).