Chlorine and Ammonia Gas through a GC with TCD & FID

[chemstation]

Hello,

I'm putting this out so I can find the exact effects that pure Chlorine or Ammonia Gas would have on a GC and its detectors as a worst case senario.

I have researched and found people have used Ammonia Gas with TCD and FID, (as a significant portion of the carrier gas), with a adverse effect on their GC column, which is fine, as I don't intend doing chromatography.

but I am worried about the Chlorine, and the corrosive effects on the instruments metals, and the detectors.

So I'm asking, Has anyone used a GC with TCD & FID to analyse for Ammonia or Chlorine Gas ???, or can tell me their effects/experiences ?

Thanking you in Advance

[chromatographer1]

Chlorine requires gold plated components which will still have a limited lifetime, a few months perhaps.

I would expect that ammonia would also make TCD components brittle, especially if hydrogen carrier was used.

My condolences on your needs of your application. It isn't easy working with such corrosive gases.

I would work with suppliers of these gases for advice in plumbing and handling them.

best wishes,

Rod

[AICMM]

Chemstation,

Do you want to analyze impurities in chlorine, level of chlorine in something else, or what?...Not sure what you are asking. Second, it does not sound like you want to do GC so why the question about impact on GC?...

The reason I ask, process GC people I have worked with have done impurities in chlorine (backflush chlorine before detector) so that is a do-able application. If it is low levels of chlorine in something else, that should be do-able as well with the proper columns and detectors. So... which is it?

Regarding ammonia, I have not specifically asked anyone about impurities in ammonia but I suspect it would be very similar to chlorine with a backflush or vent before detector. I have worked (still working on) a project to measure low levels of ammonia (0-10 ppm) and have gotten very good results without any significant instrument degradation. So... which is it?

Please provide more information if you can.

Best regards.

[chemstation]

Thanks chromatographer1 & AICMM for your replies,

the application relates to monitoring the break through time
of Toxic Industrial Chemicals, through various scrubbers. and I am assuming a worse case scenario, with pure chlorine or ammonia in the system for, eg over the weekend, running through the system.

At the moment for VOCs', the flow passes through a switching value with a sampling loop that then goes into the inlet, short connecting column, to the TCD, that then loops into the FID., and the areas of the peaks are used to detect when break through has occurred. which is why the question about impact on a GC Instrument, and not chromatography. (So all that is require to be able to do liquid injection, is change the column, and run.)

I was hoping for something similar to do for these gases without having to change the configuration. (Since I already had the Instrument and software doing what I wanted.)

there are detectors for TICs eg
http://www.globalspec.com/FeaturedProdu ... tor/1380/0

however that requires time to implement, troubleshoot, signal/noise, verify etc...., so I was hoping to use the existing configuration.

any more information would be appreciated

Thanks

[chromatographer1]

An occasional elution of chlorine or ammonia onto a TCD or FID will not pose a problem. It is the routine exposure hourly, every 4 min, etc, that will cause detector failure. Actually PID is usually done for sensitivity for ammonia. Now both should show a response on the FID and both will show a response on a TCD. You should determine the LODs for both by running samples. The columns used to separate these analytes from others should be quite different. But that does not seem to be part of your question.

best wishes,

Rod

[Bruce Hamilton]

About 10 years ago we used a GC to monitor some gaseous reaction products including wet chlorine and ammonia. The system we used was on a Pye 104 that we intended to toss out after the experiment.

We used a six port 1/16" Rheodyne PTFE valve to switch a sample directly into a glass packed column, and then into the FID and TCD.

Worked OK, but both detectors corroded badly over about two months ( lots of water vapour as well ), however it was easy to clean up the collector on the FID with abrasive paper.

Provided you can terminate the experiment quickly, you should be OK, but I'd try to minimise the sample into the the TCD, or find a cheap TCD ( eg there used to be some simple GowMac Oxygen in Air analysers that had a TCD )

Please keep having fun,

Bruce Hamilton