How to Make a 150 mM Sodium Phosphate Buffer

Question

In the SDS for the column Agilent Bio SEC-3 column you have stated to clean the column 150 mM of sodium phosphate at pH 7 is used. I was wondering how you made that 150 mM of sodium phosphate

anne_blackwell · Accepted Answer

Hello, To clarify, we don't recommend cleaning the column with 150 mM phosphate buffer. 150 mM phosphate buffer at pH 7 is a common mobile phase for analyzing samples, but not for cleaning. Suggested cleaning solutions can be found on page 2 of the user guide . The phosphate buffer used for sample analysis is made from a mixture of monobasic and dibasic sodium phosphate (NaH 2 PO 4 and Na 2 HPO 4 ) so that the total phosphate concentration 150 mM and the pH is 7. Exactly how much to weigh out depends on whether you have anhydrous or hydrated sodium phosphate salts. I typically use our Buffer Advisor software to calculate exactly how much salt to weigh out. For example to make 1 L of 150 mM phosphate buffer at pH 7 would be: 16.559 g sodium phosphate monobasic monohydrate (NaH 2 PO 4 * H 2 O) 31.231 g sodium phosphate dibasic, anhydrous (Na 2 HPO 4 ) in 1 L of water Again, those weights will be different with different hydrated forms of sodium phosphate. I'd recommend stopping a few mL short of 1 L, measuring the pH to double check it, adjusting it if needed, and then once the pH is at 7, filling up to exactly 1 L. Anne

How to Make a 150 mM Sodium Phosphate Buffer

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