Chromatography Forum

Hello everyone,

This is my first time visiting this good website. I'd like to make friends here.

I use GC/TCD FPD

Column: Supel-Q 24242 divinylbenzine 30m 0.32mm analysis:

1 NH3 diluted with Air
2 SO2 diluted with N2
3 HCl diluted with N2

Does anyone have methods for these analysis ? welcome any suggestions.

Can these analysis be conducted using GC/MS ?

Thanks,

Grace

Grace,

I hope my answer does not put you off on your first visit but more information is needed, such as why do you want to analyse these mixtures, what is the application, what concentration, how are you going to introduce the sample on to the column? Do you have to use GC. Can't you use direct-reading instruments?

Without a direct-reading instrument corrosive gases like NH3 SO2 HCl are almost always a job for ion chromatography, not gas chromatography. Sorry to be negative but for GC you would need a packed column with a custom made porous polymer. Others here may have suggestions, but think about how corrosive gases are going to affect your TC detector.

Mass spectrometry? Yes it could be done with a piece of kit called a process mass spectrometer, no gas chromatography needed. It would be custom solution and expensive.

Without knowing more about your application what I have just said may be of no use to you, sorry.

You stated no ranges in your request.

Percent levels? ppm? ppb?

These difficult analytes are not for the faint of heart.

Any metal in your system will cause problems, and I know of no MS that is not made of metal.

Are you measuring atmospheric levels and comparing with standards?

They can be done (levels?) but I would not expect the same column to be used for all three.


best wishes,

Rod

Grace,

I hope my answer does not put you off on your first visit but more information is needed, such as why do you want to analyse these mixtures, what is the application, what concentration, how are you going to introduce the sample on to the column? Do you have to use GC. Can't you use direct-reading instruments?

Without a direct-reading instrument corrosive gases like NH3 SO2 HCl are almost always a job for ion chromatography, not gas chromatography. Sorry to be negative but for GC you would need a packed column with a custom made porous polymer. Others here may have suggestions, but think about how corrosive gases are going to affect your TC detector.

Mass spectrometry? Yes it could be done with a piece of kit called a process mass spectrometer, no gas chromatography needed. It would be custom solution and expensive.

Without knowing more about your application what I have just said may be of no use to you, sorry.

Mike,

Thank you very much for your reply!

The gas concentrations are about 10-100ppm, introduce samples using a gastight syringe. The purpose of these analysis is just validating a gas supply system.

From our current experimental condition, I have to use GC/TCD FPD and a capillary column even these corrosive gases may damage the instrument parts.

But I'd like to know more about the direct-reading instruments and process MS, do you have more information about these like websites, documents?

Best,

Grace

You stated no ranges in your request.

Percent levels? ppm? ppb?

These difficult analytes are not for the faint of heart.

Any metal in your system will cause problems, and I know of no MS that is not made of metal.

Are you measuring atmospheric levels and comparing with standards?

They can be done (levels?) but I would not expect the same column to be used for all three.


best wishes,

Rod

Thanks Rod, I have to use a capillary column, do you know a better column than Supel-Q 24242?

Best,

Grace

I would use a base deactivated Supelcowax capillary for the NH3.

I would suggest a SPB-1000 capillary for the HCl.

I would suggest that the Supel Q might be the best choice for the SO2, but even it would not be a good choice.

Such analyses are better done with packed columns and a valving sample system. Hayesep C or Chromosorb 103 for NH3 1% SP-1000 on Carbopack B for HCl, Chromosil 310 in Teflon for SO2.

HOWEVER, I would NOT suggest a gas tight glass syringe would be adequate as a means of sampling and injection. Your attempt to use a syringe for sample introduction would not be reproducible or quanitative.

Good luck though.

Rod

But I'd like to know more about the direct-reading instruments and process MS, do you have more information about these like websites, documents?

Google for gas sensors or gas analyzers with ammonia etc. There is a load of choice from cheap hand-helds to floor-standing systems.

I don't advise the process MS route. It's really for situations where there are mixed cross-sensitivities too complex for the direct-reading sensors to handle. I am presuming you only have one gas per stream, otherwise NH3 and HCL together !! gives an ammonium chloride fog.

Thanks for the columns, Rod

If I use a packed column, how can I connect it to the injection port and dectector side which currently adapt to a capillary column?

We will use valve injection later, thanks for this.


Best,

Grace

Thanks Mike

I will google for special instruments for these gases later.

Best,

Grace

I would not try to use a capillary inlet for packed columns.

I would wait until you get a valve injector with inert deactivated components to do the analysis.

best wishes,

Rodney George
Senior Research and Development Scientist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

814-359-5737 voice
814-359-5459 fax
rgeorge@sial.com