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Break-Down the Emulsion
Posted: Tue Dec 14, 2010 12:16 am
by syx
Dear members,
I need to determine the quantity of water-soluble vitamins in capsules that contains lipids. I have got a problem in sample preparation since dilution with water or organic solvents tends to result emulsion. The appearance looks like egg yolk blend. What should we do to breakdown this emulsion to 2 separate phases?
Thanks in advance.
Re: Break-Down the Emulsion
Posted: Wed Dec 15, 2010 9:23 am
by HW Mueller
Adding more organic solvent, heating, centrifuging, microfiltration, or combinations might help. I have not tried this, but one can imagine that some sort of SPE could break up an emulsion.
Re: Break-Down the Emulsion
Posted: Thu Dec 16, 2010 4:26 pm
by krickos
Hi
Well not used to vitamine analys either but should be some standard procedure in like USP/NF. In any case what comes to mind apart from what Mueller already stated is pH control of your extraction.
If I understand it correctly most of your analytes are weak acids (or zwitters) which means all molecules wont be deprotonated and consequnetly an emulusion layer may apppear, by using a mild basic buffer (like carbonate pH range 8-10? ) you force your water solubles into deprotonation and an organic (toluene/heptane?) in right proportion you should be able to get a nice 2 way phase. The buffer will help as it causes a salting out effect apart from the pH control.
Read up on pKas for your vitamines and potential sidereactions that might spoil the analysis.