Autoclaved MOPS: is it supposed to be yellow?

Deborah Hailstones deborah_hailstones_at_emai at
Sun Mar 1 17:26:16 EST 1998

     I have never used DEPC treatment in mammalian RNA preps, seeing it as 
     one of those 'safety nets' that encourage slackness (like antibiotics 
     in TC....).  I have found that if you are suitably meticulous and 
     cautious it's not necessary to use DEPC, and that way you can also 
     avoid exposing yourself to (yet another) toxin....
     Having said that, my MOPS (in RNA-quality water, alone) ALWAYS goes 
     yellow after autoclaving and, if made up and then filtered rather than 
     autoclaved will eventually turn yellow with RT storage.. oxidation, 
     presumably.... yellow MOPS is definitely fine to use, no worries!

______________________________ Reply Separator _________________________________
Subject: Autoclaved MOPS: is it supposed to be yellow? 
Author:  <bburkho at > at smtpgwy
Date:    2/28/98 2:58 AM

I'm trying to set up an RNA gel for a Northern blot.
The protocol I'm using, Current Protocols in Molecular Biology 4.9.1 
-4.9.8, gives the recipe for MOPS buffer (10X: 0.4 M MOPS, 0.1 M Sodium 
Acetate, 0.01 M EDTA).
I made the solution, added DEPC to treat for remaining RNases, then 
autoclaved it.  Now my MOPS buffer is yellow, so I'm wondering if 
something is wrong.
Is this the correct way to make the buffer, or should I be making it 
with water which has previously been treated with DEPC and autoclaved?
Brett Burkholder

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