I'm making 0.1M concentration of Sodium phosphate buffer using Sodium monobasic monohydrate and sodium dibasic anhydrous. Apparently I've to add 117ml of monobasic and 183 ml of dibasic and make upto 600 ml. But while I do this my pH value hikes upto 9.0 when it's supposed to be 7.0. Can some tell me if I add excess monobasic would it resolve my issue.
Are you sure both stock solutions are at the correct concentration? From your question I would expect both to be 200mM. If you add excess of either stock solution you will change the molarity.
Thanks for the kind attention sir. Yes, my stock solutions are of 200mM. But the components in the mentioned volumes per se don't help attain the pH. I've to vary the volume of either for a pH of 7. How can I adjust the pH in this case?
Hello, for a final volume of 1L, had 57.7ml of Na2HPO4 1M and 42.3ml of NaH2PO4 1M in distilled water and you should obtain a Sodium Phosphate buffer at 0.1M, pH 7.0
Dear all,
I've checked for many possible combinations of 200mM stock of Mono and di sodium phosphate for a 100mM buffer for a pH of 7 and have concluded that an equal volume of both give me the pH7, say 450 microlitre of both, made upto 10 ml with water. Is this appropriate?
Please find the link. It will give your answer and your problem solution.
http://cshprotocols.cshlp.org/content/2006/1/pdb.rec8303.full?text_only=true
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