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How to prepare 0.5M NaOH; 50mM EDTA? - (May/22/2008 )

I am going to use 0.5M NaOH; 50mM EDTA to degrade RNA after RT reaction.
Do you know how to prepare it?


to make solutions like these, the easiest way is to make stock solutions. For instance, on my benck I have 10 M NaOH and 500 mM EDTA stock solutions. To obtain the desired concentrations, just dilute the stock concentrations (20 times for the NaOH, 10 times for the EDTA) in distilled water. Beware, EDTA is only soluble at a defined pH (around pH8) so you'll have to adjust the pH to allow the powder to dissolve if you're making the stock solution.


500 mM EDTA:
EDTA: 93.05 g of Na2EDTA (FW 372.2)
10.14 g of NaOH (FW 40)
QS to 500 mL dH2O
Stir to dissolve.
500 mM EDTA, pH 8.0 = 500 mM EDTA and 507 mM NaOH

When you dilute the EDTA to 50 mM, it already contains 50.7 mM NaOH.
500 mM NaOH minus 50.7 mM = 449.3 mM additional.

10 mL 500 mM EDTA
4.493 mL of 10N NaOH
85.5 mL Water
100 mL Total Volume