Chromatography Forum

Hi all

I am trying to analyze spray dried flavors mixtures. I have been doing HS SPME (stir bar, 1g NaCl, 1g sample, 3ml H2O in 22ml headspace vial) then (15 min equilibration followed by 30 min extraction in 50 deg water bath. 60 sec injection at 2:1 split at 260deg C. I get excelent GC from it.

Anyways as typical for SPME the precission isn't great especially for some compounds. I was looking for a solvent that I could use to extract it but I've tried MeCl2, Chloroform, acetone and hexanes and literally see nothing but solvent on the GC/MS. Is there anything else I can use?

We typically use methanol as solvent to analyze fragrances, like by GCMS. A typical fragrance can easily have 100 components, so each component can be at a low level. When we investigate finished products at maybe 1% fragrance, solutions of 2.5% finished product sample show some fragrance peaks.

I'm just wondering why I am getting 0% recovery using every solvent in my lab and only headspace works. Methanol is great in that it doesn not appear on the GC/MS (m/z 32 I don't scan below 40) but it doesn't dissolve many of my more nonpolar analytes. If it dissolves in MeOH then it should also dissolve in acetone.

Might I need to defat or something.

Are the flavours encapsulated ? - if they are you need to find something that dissolves the encapsulation, or give them a vicious grinding.

Peter

I would suggest THF, possibly mixed with a small amount of water. Ethylene glycol monomethyl ether is another possibility.

Headspace works without a solvent as the volatiles permeate into the vapor phase.
Using a smaller vial and using longer heating times may improve your analysis.

Good luck,

Rod

We definately don't want THF arround for safety reasons. How about DMSO, though that will come out 1/3 of the way into the chromatogram and cover up a lot of stuff. That will disolve almost anything.

A reasonable choice.

Heat might also be tried, with obvious possible problems.

Rod

The samples are encapsulated in starch. I am told in the past they just used MeCl2 and let it sit in it for days then injected it splitless.

Then EGmonoMeEther could be an excellent choice. (2-Methoxyethanol)

best wishes,

Rod

actually I might just need to dissolve the sample in saturated NaCl water and then do an extraction rather than just try and dissolve it in organic solvent. The trouble will be in pulling some of the more polar flavors out of the water.

That sounds like a plan.

Remember that a small sample and complete evaporation of the water solution should give you good results at trace levels.

best wishes,

Rod

Have you tried ultrasound to disrupt the encapsulation ?

Peter

I frequently use a Branson 1510 sonnicator bath to mix samples. I just recently started hearing about ultrasound assisted solvent extraction. It that the same thing or do you need special equipment. One paper I read listed a Misonix S3000 and 20 khz. Is that the type with the hand probe?