We used the one step method in the lab to obtain FAME for our GC analysis.
Many time we see varying degrees of evaporation of solvent (BF3 and internal standard) from our test tube during the 1 hour heating.
We tried putting PTFE tape around the thread of the test tube but we have varying success rate.
How would you effectively prevent evaporation of solvent in a screw-capped test tube during heating in a water bath?
See here for the simplified method we used: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2593112/
Please look at the following below links which may help you in your analysis:
https://www.nrel.gov/docs/fy16osti/60958.pdf
http://www.diva-portal.org/smash/get/diva2:10699/FULLTEXT01.pdf
https://www.researchgate.net/post/What_is_the_oily_looking_thing_after_drying_hexane_containing_methyl_esters_of_my_sample
Thanks
May I ask why you're spiking an internal standard before processing (heating the sample)? Is it possible to add it to the processed sample just prior to analysis? Any processing you do to an analytical standard may negatively impact your method (due to methodological error).
Thank you all for the answers.
Dr. Elgailani , crimped vials seem to be a good idea but not feasible at the moment. Maybe we will consider about it for future purchase. As of now, we students still rely upon reusable screw-capped borosillicate test tubes.
Dr. Käfferlein , other similar methods state the use of a heater at 100'c. I assumed they mean water bath on a heater. Personally I think it's only necessary to heat the liquid portion of the test tube rather than the whole test tube. But I could be wrong. Septum does not apply as here as I now using a screw-capped test tube with no septum.
Dr. Guild , the internal standard required to be trans-esterified into methyl ester so that it can be analyzed on the GC. The requirements to add in before heating are specified in several papers presenting similar methods.
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