GC-FTIR

[twranger]

Anyone familiar with this technique? I just ran across an ad for an HP5965 IR detector that worked with Chemstation just like mass specs. Apparently there was little interest because HP didn't sell them for long. What would such a setup be useful for? Seems to me a rather inexpensive screening tool for unknown samples, but I guess everyone just dumps it on their MS for that info.

[Don_Hilton]

The last I saw of the IR detector, Bio-Rad was selling it - and this was some time back. I've not checked to see if they are now or if the product has wandered of to somewhere else. I gather the problem is short path length, low concentration and short signal acquisition time don't combine well to give a useful IR spectrum.

[Peter Apps]

Adding to what Don says - the underlying problem is poor detectability, you need much more analyte to get a sensible signal from FTIR than you do with the other GC detectors, and in general there are more efficient ways of getting the selectivity that IR would provide. A similar fate befell the HP/Agilent atomic emission detector - there are just too few labs out there doing the kind of work for which it is useful.

I did some back of envelope jottings a few years ago, and it might be possible to interface cavity ringdown FTIR with GC.

Peter

[James_Ball]

I remember seeing adds for those HP IR detectors back when I first started in the lab about 1991. Never saw much more than the adds though, but I believe there is a method posted in SW846 using it.

This detector probably had the same fate as the Super Critical Fluid Extraction system HP/Agilent developed in the early 90s, no regulating agency would ever approve its use in a method so no one bought it.

[DanFSIV]

I'm currently playing with a GC-FTIR.

There's a vapor phase and a solid phase, the solid phase is more like what you're used to with a benchtop FTIR. We have a vapor phase and you need about 5mg/ml to get a decent IR out of it. When you're used to working with MS that is a ridiculous concentration. Granted it hasn't been operating for long, so there may be some method tweaking that can be done. The software does a pretty good job of producing a nice IR. The vapor phase charts are nicer than typical vapor phase but still not as detailed as solid phase.

ASAP Analytical is producing the detector now.

[Peter Apps]

I'm currently playing with a GC-FTIR.

There's a vapor phase and a solid phase, the solid phase is more like what you're used to with a benchtop FTIR. We have a vapor phase and you need about 5mg/ml to get a decent IR out of it. When you're used to working with MS that is a ridiculous concentration. Granted it hasn't been operating for long, so there may be some method tweaking that can be done. The software does a pretty good job of producing a nice IR. The vapor phase charts are nicer than typical vapor phase but still not as detailed as solid phase.

ASAP Analytical is producing the detector now.

Please keep us posted with progress - although improving the sensitivity by a minimum of three orders of magnitude will be needed to make it useful for capillary GC

Peter