Hi,

first prepare 100 mM stock solutions of monobasic sodium phosphate (NaH2PO4) and dibasic sodium phosphate (Na2HPO4).

To make 1 L of each stock solution:

Dissolve 15.6 g of NaH2PO4 in distilled water with a final volume of 1 L to make 100 mM NaH2PO4. Dissolve 14.2 g of Na2HPO4 in distilled water with a final volume of 1 L to make 100 mM Na2HPO4.

To prepare 1 L of 100 mM phosphate buffer at pH 7.0, mix 70 mL of the monobasic 100 mM NaH2PO4 solution with 930 mL of the dibasic 100 mM Na2HPO4 solution

Check the pH of this solution and adjust to pH 7.0 with mono or dibasic solution if necessary.

Dissolve 166g of potassium iodide in 100 ml of the previously prepared 100 mM phosphate buffer at pH 7.0

Finally, bring up to 1 L with distilled water

adjust the pH if necessary

Hope this helps

Best,

Murat