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RNA in situ hybridization: pH of AP staining buffer? - (Jul/16/2012 )


I'm starting to do RNA in situ experiment and I have a working protocol for that. I just wonder the recipe of the AP staining buffer:

100 mM NaCl
50 mM MgCl2
100 mM Tris pH 9,5
0,1 % Tween-20

Why the pH is that high? I have checked also other protocols as well as kit manuals and they say the same. Tris isn't working as a buffer at pH 9,5!


9.5 is just outside the buffering range of tris. it will resist change of pH towards the acidic.