Sodium Phosphate manufacture uses sodium dihydrogen phosphate and disodium hydrogen phosphate. PBS manufacture uses pottasium ohosphate monobasic, sodium phosphate dibasic and sodium chloride. Yet, these buffers seem to be used interchangeably in many searches. These are two different buffers yes?
Further to this why cant you just manufacture sodium phosphate by adding sodium dihydrogen phosphate and disodium hydrogen phosphate in the same cylinder? Why must we prepare 1M etc separate stocks and then mix them in? If I can mix them in the same cylinder and pH with HCl or NaOH, would that not suffice?
Sodium phosphate is an incomplete description of the chemical. It could be trisodium phosphate (Na3PO4), dibasic sodium phosphate (Na2HPO4) or monobasic sodium phosphate (NaH2PO4). It is necessary to be specific.
PBS (phosphate-buffered saline) is also insufficiently specific. The exact composition varies. People are not always careful to define its composition.
The easiest way to make sodium phosphate buffers in the pH 6-8 range is to mix solutions of monobasic and dibasic sodium phosphate. You don't even have to use a pH meter. You can use a chart that gives the necessary volumes to achieve any pH in that range.
You could also add NaOH to monobasic sodium phosphate to raise the pH. This amounts to the production of dibasic sodium phosphate.
Using HCl to lower the pH of dibasic sodium phosphate results in the production of NaCl. You can do this if you don't mind having NaCl in your sodium phosphate solution.
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