Protonate the phospholipid using acid. Wash the excess acid and salt from the product.
- Separatory funnel (teflon stopcock) or suitable glass vessel
- Rotary evaporator or nitrogen/argon stream
- pH indicating paper
- Deionized water
- Dissolve the lipid in a volume of chloroform: methanol (2:1 v/v) such that the lipid con centration is 10-50 mg/ml. (e.g. 9.0 ml)
- Add deionized water to the solution. (0.2 times the volume of the chloroform: methanol: e.g. 1.8 ml)
- Shake the solution and let the phases separate.
- Adjust the water phase to < pH 3.0 using acid. (pKa of the phosphate is approximately 3.5.)
- Shake the acidified solution and allow the phases to separate.
- Isolate the bottom phase. (This phase contains the acidified phospholipid.)
- Remove the chloroform by rotary evaporation or nitrogen/argon stream under a hood.
- Dissolve the residue in a suitable organic solvent.