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low ppm H2S analysis with silicagel concentrator tube?
Posted: Fri Oct 19, 2007 7:33 am
by vega
Dears,
I have to analyse H2S 0,1 ppm with micro-GC (TCD detector).
I try to use concentrator with silicagel tube.
I'm not sure if it is the right substrate for adsorbing H2S.
Please, do you have experience on it?
Is silicagel correct for that?
What is the correct temperatur to desorbe and inject?
Thank you
Ciao
Posted: Fri Oct 19, 2007 12:12 pm
by chromatographer1
Plain silica gel would not be a good choice. It would be difficult to quantitatively desorb the H2S.
If you were to have deactivated silica gel, C1, C4 or C8 or C16, it might be a good choice.
That is my opinion for what it is worth.
best wishes,
Rod
Posted: Fri Oct 19, 2007 2:22 pm
by vega
Dear Rod,
suggestions?
I do not understand what is silica gel deactivated.
Is not preferable to use TENAX or Active carbon?
Thank you
Vega
Posted: Fri Oct 19, 2007 3:00 pm
by chromatographer1
I refer to silica gel that has been chemically reacted to block the silanols.
It corrresponds to LC packing that has been reacted to bond a C18, C8, C4, or C1 to the surface.
Yes there are other packings that could be used to trap and desorb H2S.
Without knowing the details of your matrix choosing one specific packing is difficult.
I would call Supelco Technical Service (yes it is free) and ask their advice after you discuss your matrix and instrumentation.
800-359-3041
techservice@sial.com
best wishes,
Rod
Posted: Fri Oct 19, 2007 6:10 pm
by chromatographer1
If you really want to make the silica gel packing yourself, I believe a classical reaction with silica gel using DiMethyl DiChlorosilane in toluene and then rinsing with methanol will give you a C1 surface.
I wish I could find my old chemistry books.
I would buy the packing. Easier than doing it yourself.
best wishes,
Rod