Change to strong acid, examples HCl.
Glacial is a weak acid, it won't change the solution pH quickly.
Use however much you need to neutralize. You need it to be acidic to precipitate the SDS out. (or rather double check your protocol, and find the step where you're adding too much base or too little acid ;-)
Well. you didn't mention which solution you need to adjust and to which pH? Solution I, II or III? If you want to adjust your solution to acidic pH you have to add HCl or if basic you need to adjust with NaOH.
Thank you all for your answers. I need to prepare solution III which is known as neutralizing solution. In the protocol it is written to use glacial acetic acid. Can i use HCl instead of glacial acetic acid?
Did you find an answer to your question because I am using glacial acetic acid to adjust pH and it is taking forever, I am almost run out of it. Can i switch to HCl even tho the protocol (Mehlich 3 extractant says glacial acetic acid)
There are several varieties of the P3 solution (neutralizing solution P3), the common thing is 3 M potassium (or sodium). Some protocols state adjusting pH to 4.6-5.5 and some state getting 5 M acetate final (adding 11.5% final volume acetic acid to 3 M K/Na-acetate). The original protocol by Birnboim and Doly used pH 4.8.
Adjusting them to pH 5.2 (or below) will require about 50% (and then more!) the final volume be acetic acid. Some protocols incorrectly state that 3M/5M variant has pH 5.5 while most do not state it's pH - in fact it's pH 6.66 but it will go below 6 upon dilution.
Any of these P3 can neutralize 0.08 M NaOH in the alkaline lysis and still make the final mix (often quite) acidic. The variants with >50% acetic acid may be beneficial as low pH and > 15% final acetic acid can denature and precipitate more protein during the alcohol precipitation step. Also, such P3 likely will never need any additional sterilization.
As you may notice, the pH of these P3 variants is about 1 unit higher than can be expected from the pKa 4.8 of AcOH in water. That's because the actual solvent of these concentrated solutions is not water but it's mixtures with high amounts of acetic acid.
