I have made some liposomes (LUVs) and separated dye encapsulated liposomes from free dye via gel filtration, which obviously means some loss of sample. I can't use Stewart assay (I have some PG content) or Bartlette (liposomes are in inorganic phosphate). How can I calculate /measure the lipid concentration in my sample post gel filtration?
Dear Dyan Ankrett ,
I tend to say use a combination of extraction and TLC.
A famous and often used method is Rouser et al. (cited more than 3000 times in Google Scholar):
Rouser, G., Fleischer, S., & Yamamoto, A. (1970). Two dimensional thin layer chromatographic separation of polar lipids and determination of phospholipids by phosphorus analysis of spots. Lipids, 5(5), 494-496.
https://link.springer.com/article/10.1007/BF02531316
Another good reference is:
Article Methods of extraction and thin-layer chromatography determin...
Best regards.
You can also use this very easy 1H NMR based method: https://pubs.rsc.org/en/content/articlelanding/2016/ob/c5ob02480c#!divAbstract
It uses an internal standard (TMSP-d4) to quantify the abundance of the methyl group at the end of the acyl chains.