Purification Methods
Glycerol phosphocholine is purified via the CdCl2 complex which is recrystallised four times from 99% EtOH by standing at 0o for 1hour. The white precipitate is collected, washed with EtOH, Et2O and dried in a vacuum. The amorphous Cd complex can be converted to the crystalline form [C8H20O6NP.CdCl2.3H2O] by dissolving 34.4g in H2O (410mL), and 99% EtOH (1650mL total) is added slowly with stirring and allowing the clear solution to stand at 25o for 12hours, then at 5o for 12hours. The crystalline complex is filtered off, washed with cold 80% EtOH and dried in air. Glycerol phosphocholine can be recovered from the complex by dissolving it in H2O (2% solution) and passing it through an ion-exchange column (4.9 x 100cm, of 1volume IRC-50 and 2volumes of IR-45). The effluent is concentrated to a thick syrup at 45o. It is dried further at 50o/P2O5/48hours. The vitreous product (8.25g) is dissolved in 99% EtOH (50mL), and the clear solution is cooled at 5o, whereby crystals appear and then at -15o for 16hours. The crystals are filtered off, washed with 99% EtOH, and Et2O then dried at 50o in vacuo over P2O5. It can be recrystallised from 99.5% EtOH (long prisms). It is hygroscopic and must be handled in a H2O-free atmosphere [Tattrie & McArthur Biochemical Preparations 6 16 1958, Baer & Kates J Am Chem Soc 70 1394 1948, Acta Cryst 21 79, 87 1966].
