Preparation of sodium phosphate buffer solution

[minimint89]

hi guys,

How can I prepare 20 mM sodium phosphate buffer (pH 6.9) containing 10 mM NaCl ? I mean how many grams of sodium dihydrogenphosphate, disodium hydrogenphosphate and sodium chloride are needed for 1 L of buffer solution. The buffer solution is prepared at room temperature (25C) and use at 37C.

Thank you

 

[sjb-2812]

What equations do you know that may help?