exchanging FID with TCD

[DaBrainz]

Hi all

I currently have an Agilent 5890 with 2 FIDs. I require the use of TCD to measure oxygen headspace for lyophilized product vials. My managment wants to go the cheap route and switch one of the FIDs out on our current instrument with a TCD.

Is this an easy thing to do and are there any concerns about chemstation connectivity? I think because its a 5890 that Agilent probably would not do this work. I'm leaning towards contacting my service guy to do it but this kind of work might be out of his scope.

Any thoughts on where to start?

[Consumer Products Guy]

This can be done. However:

You need 5890 TCD parts, so you better have these already, or try to find some used. You need the plumbing parts and I believe a detector board. I would doubt that Agilent would still have any around, the 5890 has been out of support for quite a few years.

Similarly, I really doubt that Agilent would do such swap/install. You'll likely need to do by yourself, or get a third-party vendor who does this type of work. Such companies would include Full Spectrum, AOT (Alpha Omega Technologies), and others who also typically buy up and have some obsolete parts.

That said: the 5890 is an excellent unit, still.

Have you considered a dedicated oxygen analyzer of the task you're attempting?

[chromatographer1]

I would suspect that a swappable HID from Valco might be a possibility. Then you would have the sensitivity of a FID for the fixed gases.

You might discuss this with Valco or with Gow-Mac to see if one of their units could be a choice.

best wishes,

Rod

[CE Instruments]

Buy another second hand 5890 with a TCD in. Likely to be far cheaper than trying to mod your existing GC
TCDs need to be thermally stable so it does not just sit on top of a GC so even if you get the parts cheap it will cost a lot for an engineer to fit. Use your own ? What if the Gc gets damaged
I would not advise adding an HID to an existing GC these are very sensitive and have problems with leaks. They are more expensive than a whole new GC with TCD too !

[AICMM]

DaBrainz,

First, the direct answer to your question. Yes, a TCD is swappable with an FID if you have the mechanical abilities and the parts. It's tedious but not rocket science.

Second, I am with Chromatographer1 in saying that you should think about an HID. I have a well known bias in this regard in that I make an HID but there are other reasons as well. For one thing, if you are looking at low levels of O2, the HID will be much, much more sensitive. Furthermore, it will not be all that difficult to install an HID in place of a TCD on a 5890 chassis (I have done this numerous times) since you can use the same electronics, plumbing and heater with minor modifications. Finally, HID's are not really all that fussy as evidenced by numerous customers of mine that have them installed in various GC's, process and laboratory. I don't use a getter (nor do most of my customers) and I don't use any fancy plumbing and I can easily see 10 ppm or less of the fixed gases. Considering you already have the FID electronics, plumbing and heater, this will also be a relatively inexpensive option, especially considering how hard I think you will have to look for a 5890 TCD (unless you already have one!)

I believe the Valco PDD will retro-fit on a 5890 without too much work, I know mine will, and I am almost certain that a Gow-Mac DID will not since it is normally part of their own GC.

If you would like me to talk your ear off about this, feel free to contact me at aicmm at flash.net

Best regards,

AICMM

[chromatographer1]

My apologies to AICMM.

I forgot to mention your company. Many find MM's assistance helpful. Many find the big companies don't often have time to assist the little man, where AIC and MM will make the time.

I meant no disrespect. Sorry.

best wishes,

Rod

[DaBrainz]

Thanks for your input. I have contacted my local service tech and he says he can do it, if the quote looks high I may start looking at second hand GCs or maybe some cheap compact models for this dedicated use. I do not need the sensitivity of the HID as the lowest amount I would be looking for is around 1% oxygen in Nitrogen. My analysis is to be headspace of pharma vials. The QC labs at my site run this consistantly by doing a manual injection onto a molecular sieve glass column. I will probably just use thier existing method.