methanol in air

[tibor19]

We deal with measuring air quality with ATD-GC-MS. We use Carbotrap 300 multibed adsorbers. So far we measure BTEX. Our new task is measuring other component in air. I think the main problem is methanol. Is this adsorber proper for this considering the low breakthrough volume of methanol? Could you recommend any method and/or literature for this problem?
Should we use other detector (FID)?

Thanks, for your help

[krickos]

hi
have not done air sampling for a very long time and used similar adsorber as you do.

However if i am not uncorretc you will find info in EPA methods EPA TO-15 and EPA TO-17, should include a target ion for methanol and a recommendation for adsorber (Spherocarb).

[LCbob]

Hi

Try it and see


I did this years ago, I used tubes with 2 different sorts of adsorber in, I think Tenax and another, cannot remember its name. Theory being the low boilers which were not captured by the 1st went through to the second. Seemed to work for most lab solvents.
FID would be better considering the lower molecular weight, ultimately depends on the sensitivity you are looking for.

[Mainzer]

What is your intention: workplaces or indoor air? For workplace atmosphere we use 300 mg Chromosorb 106 and the maximum air volume is 200 mL absolut, with 5 mL/min you can sample 40 minutes.

BTV at 23° is 1 percent at 300 mL.

For indoor air we a sandwich of 130 mg Tenax TA and 200 mg Unicarb, but in this case you have to purge the tube with Helium at 50 degrees ("heated dry purge"). Stabilty testing must still be taken.

Detector is FID and the column a 30 m DB-624, 0.25 mm ID and 1,4 µm film thickness.

[tibor19]

Hi
Thanks,
I'd like to measure in workplace in oil laboratory/plant. The minimum volume of my pump is 20ml/min.
Now I use HP-1 MS column 30m * 0,25mm * 1 µm. Is it good for this task?

[AICMM]

tibor19,

I would contact Scientific Instrument Services. They have a lot of data on different breakthrough volumes for a variety of trap materials and compounds.

A HP-1 without a pretty thick film is probably not a great choice for methanol. Either the film has to get thicker or the phase should change....

Best regards,

AICMM