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Question about SPME, solubility, and volatility.
Posted: Wed Jun 04, 2014 7:24 pm
by Lawborne
I'm working with SPME to determine how well a certain steroid (androstenone) volatilizes in the air. When I have it in isopropyl alcohol I get a peak in GC-MS but when I have the same concentration in any type of oil (I've tried canola and Crisco) I do not see any peak. If I had to guess it is because androstenone is very soluble in oil compared to isopropyl alcohol so it is less likely to become volatile. Thanks in advance.
Re: Question about SPME, solubility, and volatility.
Posted: Wed Jun 04, 2014 8:09 pm
by Peter Apps
I'm working with SPME to determine how well a certain steroid (androstenone) volatilizes in the air. When I have it in isopropyl alcohol I get a peak in GC-MS but when I have the same concentration in any type of oil (I've tried canola and Crisco) I do not see any peak. If I had to guess it is because androstenone is very soluble in oil compared to isopropyl alcohol so it is less likely to become volatile. Thanks in advance.
That about sums it up.
Androstenone is a much larger molecules than is usual for SPME sampling and I would be interested to hear how well it performs since I am also working on airborne chemical signals:
http://www.bpctrust.org/bioboundary-project.asp
Welcome to the forum.
Peter
Re: Question about SPME, solubility, and volatility.
Posted: Thu Jun 05, 2014 2:50 pm
by Steve Reimer
The octanol - air partition factor is not favorable for large and not very polar compounds in oils. I see less than 10% of the response when comparing naphthalene from water and naphthalene from waste oil when I do headspace (vacuum distillation in my case).
I see that Henry's law constants along with Kow and Koa data is available on Chemspider. It could give you a good starting point.