How long is DTT stable for at 4deg? - (Nov/09/2010 )

Hi all,
I am always making a buffer containing 10mM phosphate, 5mM DTT and 2mM EDTA, and i was just wondering how long DTT is stable for at that concentration at 4deg to see if I could make enough to last a few weeks

DTT is less stable in aqueous solutions. According to Maniatis, dissolving DTT in 0.5 mM Na2EDTA will increase the stability.
DTT has an absorbance peak of 220 nm, while the oxidized form has a peak at 300 nm.

NattyB on Tue Nov 9 19:13:35 2010 said:

50 mM buffer pH value 2 mM DTT is 50% oxidized
Tris®-HCl 7.6 22 hours
Tris®-HCl 8.0 5 hours
Tris®-HCl 8.5 2.5 hours
Tris®-HCl 9.0 1.5 hours
Note that DTT is stable in aqueous solutions < pH 7.6, but degrades rapidly at higher pH.

Thank you very much, ill just make stocks of each component and and DTT on the day

I turn out a stable solution of DTT (reducing reagent) useful for determining Albumin Cobalt Binding (ACB), using as Good's buffer the 2-morpholino acetic acid (MES) 50 mM at pH 5.5 that not form any radicals*, in which 1.5 mM of dithiothreitol (DTT), 1% sodium dodecyl benzene sulfonate or 0.01% Triton X-100 as stabilizer, and 1% NaN3 as preservative are used. Before bottle opening , the reagent remains stable, protect from light, for 12 months at 2-8 °C, while, after opening it, the stability not is beyond 30 days at 2-8°C, always from light protect.

*Grady JK1, Chasteen ND, Harris DC. (1988) Radicals from "Good's" buffers. Anal Biochem. 15;173(1):111-115.