I have a 1 mg/mL stock of C24 in hexane. I added 50 uL of this to Organic Acids extract before drying down and derivatizing. I then add 100 uL BSTFA and 1 uL is injected (total 0.5 ug).
Relevant GC conditions are:
20:1 split ratio
Run time 45 minutes
Front inlet: 250C
Split flow: 20mL/min
Total flow: 24 mL/min
Column: Rtx-1 (non polar) 30m x 0.25 mm x 0.25 um
Initial temp 90C for 4 min - various ramps and temps up to 275C.
I have seen a tiny peak doing it this way.
When I do straight injection in hexane (0.5 and 1 ug injected), there is nothing even after ion extraction.
Thanks!
Hello Danielle, Thank you for your interesting question.
At first glance, your method looks like a very common separation method that we used to analyze oleochemical products at BASF on a daily basis (hydrocarbons, fatty alcohols, fatty acid methyl esters, etc.). Nevertheless, with a boiling point approaching 400 °C, tetracosane is clearly a very high-boiling compound. Although the injector temperature does not actually need to reach the boiling temperature of the analyte to vaporize it due to the small amount injected, I am concerned that this is where your problem lies.
You could try increasing the injector temperature so that the sample does not remain in the liner, or steal away through the split outlet.
The maximum oven temperature may also be important. There are columns from Phenomenex that can tolerate over 400 °C for a short time. They carry the suffix "Inferno", e.g. Zebron-5HT Inferno.
I hope that my answer can help you and wish you much success in your research.
Florian Morsbach Thanks for your thoughtful reply! We figured it out - turns out the run wasn't long enough to detect it! C22 eluted at the end of our run, so mystery solved. Thanks again.
Please look at the following below links which may help you in your analysis:
https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/260/555/r8769bul.pdf
Thanks
Isam Eldin Hussein Elgailani Thank you for taking the time to share these resources.
- Badges
- Science topic
- Similar topics
- Counseling Psychology
- Confusion