Purification can be carried out by passage through a DEAE-cellulose formate column, then through a Dowex 50 (H+) column to remove Na ions, concentrated by lyophilisation and redissolved in H2O. It is commercially available as a solution of 0.05g/mL of H2O. The concentration of acetoacetylcoenzyme A is determined by the method of Stern et al. [J Biol Chem 221 15 1956]. It is stable at pH 7-7.5 for several hours at 0o (half-life ca 1-2hours). At room temperature it is hydrolysed in ca 1-2hours at pH 7-7.5. At pH 1.0/20o it is more stable than at neutrality. A solution of the trisodium salt (0.05g/mL H2O) adjusted to pH 5 with 2N NaOH can be stored frozen for several weeks. It is stable at pH 2-3/-17o for at least 6 months. [Hersch & Jencks J Biol Chem 242 3468 1967, Clikenbeard et al. J Biol Chem 250 3108 1975, Simon & Shemin J Am Chem Soc 75 2520 1953, Moffatt & Khorana 81 1265 1959, Salem et al. Biochem J 258 563 1989, Beilstein 26 III/IV 3668.]