Purify the pyrophosphate by ion-exchange chromatography on Dowex-1 formate [Bloch et al. J Biol Chem 234 2595 1959], DEAE-cellulose [Skilletar and Kekwick, Anal Biochem 20 171 1967], or by paper chromatography [Rogers et al. Biochem J 99 381 1966]. Likely impurities are ATP and mevalonic acid phosphate. Store it as a dry powder or in a slightly alkaline (pH 7-9) solution at -20o.
