Citrate buffer preparation
I am struggling to find a formula on how to prepare Citrate buffer pH 5.5 out of kitchen Citric acid (monohydrate) and Trisodium citrate dihydrate (I get it reacting citric acid with baking soda).
I am confused since one formula is provided by Ethyl ascorbic acid manufacturer. There is a suggestion to use 84% water, 1% citric acid and 15% sodium citrate to get a buffer pH 5.5.
Then there is a web-site to calculate the buffer: https://www.aatbio.com/resources/buffer-preparations-and-recipes/citrate-buffer-ph-3-to-6-2
Although there is a dehydrated citrcic acid used, I recalculated it to monohydrate using their g/mol values and got 6,235g citric acid and 20.684g sodium citrate, which is not 1% and 15% like above.
Then I also found this table https://www.sigmaaldrich.com/UA/en/technical-documents/protocol/protein-biology/protein-concentration-and-buffer-exchange/buffer-reference-center#citric2
They don’t have pH 5.5 buffer in the table, but for pH 5.4 it is 5,358g Citric acid and 21,910g sodium citrate. The relation is different again! I am confused
So my question is what is the formula for Citrate buffer with above ingredients to get pH 5.5. Also, is there any standard, or common, or widely used percentage of buffer which used by formulators?
Thank you in advance!
Log in to reply.