12.06 g of sodium phosphate dibasic

50.25 mg (0.05025 g) of EDTA (Ethylenediaminetetraacetic acid disodium salt dehydrate)

150 mL methanol

in 850 mL HPLC water

pH 6.50

[use HPLC grade O-phosphoric acid (85%) or 6.25 N sodium hydroxide to pH the mobile phase; Fisher Cat # A260-500]

Catalog numbers from suppliers:

HPLC Water, Fisher

HPLC Methanol, Fisher Cat # A452-4

Ethylenediaminetetraacetic acid disodium salt dehydrate, Sigma Cat # ED2SS

O-phosphoric acid (85%), Fisher Cat # A260-500

6.25 N sodium hydroxide, Fisher Cat # SS263-500

Sodium phosphate dibasic, Fisher Cat # S374-3