I am analyzing oxidized phospholipids in human plasma. After lipid extration using methanol and centrifuge, the supernatant containing lipids were dried using a vacuum evaporator. Then the residue were reconstituted in methanol for further LC-MS/MS analysis. However, the sample were found to be Inhomogeneous. I suspect liposome formed because the remaining supernatant contained higher proportion of water as the supernatant was evaporated in vacuum evaporator. So can liposome be degraded by vacuum dry for a longer time or choosing other organic solvents to reconstitute the residue?
Hi Haonan,
did you extract your lipids only with methanol? Was the plasma sample freeze-dried before the extraction? What was the ratio of methanol to your sample? These parameters can affect your extraction.
Anyways, liposomes, or any water remained in your sample can be removed by longer freeze-drying, e.g. 2-3 hours should be enough, but can be even longer.
Actually I do not believe that your inhomogeneity after methanol reconstitution is due to liposomes. That would need quite a lot of water or water-based buffer in your methanol-reconstituted sample - it is very unlikely. I think your extraction yielded a mixture of lipids, some of which simple were not dissolvable in a smaller amount of methanol - this highly depend on the lipid classes present in your extraction. I suggest dissolving your vacuum-dried extracted lipids in a mix of chlorofom:methanol at a ratio of 2:1 or 1:1 (try both).
Best, Karoly
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