I am currently trying to extract phenolic compounds from milk to be quantified with gas chromatography techniques (GCFID with liquid injection). Till now I have not found any robust method... does anyone have any suggestion?
Dear Andrea,
(Poly)Phenolic compounds are secondary metabolites of plants and usually associated with organoleptic properties such as colour and taste. I guess you plan on characterizing the phenolic extract of plant derived milk like soy, rice or barley. Or are you planning on looking at biological samples (breast milk, cow milk, sheep milk)?
In either case because milk doesn´t have colour, the concentration ranges will be extremely low (compared to plant extracts or fruit juices) so you have one of two options: either you use an extremely efficient extraction methods or extremely sensitive detection methods (i.e. Orbitrap MS). Because (poly)phenols are such diverse family of compounds it is almost impossible to garantee a good partition of (poly)phenols accross one specific solvent system. So you need to have some sort of compromise.
I have some experience with extracting polyphenols from biological samples (blood plasma). Again because the levels are extremely low any contamination could hamper your downstream detection process. So always use high purity solvents, clean glassware material (avoid plasticware material), otherwise you´ll detect plasticizers in your sample.
Hope these tips will help your research.
Best regards,
Ana
you can follow this instructions as suggested by Brett Savary ,,, you first treat with trichloroacetic acid (8-10% final) to acidify solution and precipitate protein, clarify, and then apply solution to an appropriately conditioned C18 solid phase extraction cartridge. Wash with water, maybe pre-elute the SPE cartridge with 5-10% solvent, and then elute phenolics with aqueous solvent (e.g., 80% EtOH or ACN).
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