I am currently attempting to develop a method using thermal desorption / GC fid for an occupational exposure monitoring program. Does anyone have experience of using thermal desorption for C2 - C5 alcohols and if so what type of adsorbent would be useful in the monitoring tubes.
By Anonymous on Monday, July 10, 2000 - 10:10 am:
Try Supelco Tech Service: 800-359-8041. Their expert at TD occupational exposure monitoring is Jamie Brown.
By sean sweeney on Tuesday, July 11, 2000 - 03:59 am:
I was hoping for someone with personal experiences as I am new to the whole thing and I am considering using activated charcoal but am a little concerned about retention on the packing.
By Ron on Tuesday, July 11, 2000 - 05:40 am:
There is a great deal of information on the SIS web site, sisweb.com. There are tables of the breakthrough volumes of various adsorbent for alcohols, which should get you up and running.
By Mike on Thursday, July 27, 2000 - 04:24 am:
Responses to this question will be limited here, this being mainly a USA-based forum. There is a screening method NIOSH 2549 and a compendium EPA method TO-17. However, the primary source for these two TD procedures is the UK Health and Safety Executive (HSE) workplace method MDHS 72. The European Standard for test methods which takes TD into account is EN 1076:1996.
The answer to your question about sorbents for alcohols is probably Chromosorb 106. Using a method similar to that of SIS and Supelco (but more rigorous - no space to go into details here) I measured the following "infinite dilution" capacities in L/g at 20C: methanol, 1.3; ethanol, 8; n-propanol, 56, n-butanol, 320. I would make the sample volume as small as possible, say <0.5L on a 250mg tube.
See also R.H.Brown (1996). What is the best sorbent for pumped sampling - TD of VOCs? Experience with the EC sorbents project, Analyst, 121,1171-1175.
Be cautious if you must sample alcohols on carbons for TD. There may be decomposition which will not necessarily be the same for calibration and sample tubes. In any case, to comply with EN 1076, desorption efficiency in TD must be greater than 95%.
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