To detect H2,CO,CO2,CH4, C2 C3 hydrocarbons

[kellylen1412]

I need a column tht is able to do the above mentioned for me..i read from the catalog that Supelco Carboxen-1010 PlOT is able to do so for me.
Can anyone advise me more on it. Wht kind of detector and carrier gas tht i need to use?

[chromatographer1]

First of all, helium carrier. You need a special ionization detector or a TCD. If you insist on using capillary your detection limits will be high if you use TCD.

There are a few alternatives to a TCD on the market:

Advanced Industrial Chemistry Corp.

Gow-Mac

Valco

Your requirements are served by using multidimensional chromatography, but this is more complicated than a single column single dimensional chromatography system.

If you do not have any N2 or O2 in your sample (you did so indicate this) then a porous polymer column will separate the components you mentioned. A "R" or "N" polymer is recommended and a length of 3 meters. You may require oven temperature programming to elute the C3 hydrocarbons in a timely manner.

Feel free to contact Supelco Technical Service if you have any questions.

best wishes,

Rodney George
Supelco

[AICMM]

kellylen1412,

As Rod notes, helium is the best choice for carrier if you want any kind of sensitivity at all for these components. Even then, the sensitivity for hydrogen on a TCD using helium carrier is extremly poor. Most people who want to do lower level hydrogen use a helium ionization detector or use argon as the carrier for the hydrogen analysis.

I think you would be well advised to not limit yourself to a PLOT column since you will not be flow restricted with a TCD or helium ionization detector. Micro-packed and packed columns could provide you with substantially better detection limits.

Feel free to contact me if you want more detector information. Rod has also got lots more info on columns if you contact him through Supelco.

Best regards,

Matthew
Advanced Industrial Chemistry Corp.

[kellylen1412]

I have a TCD Dectector which i was made to understand is sufficient enough to detect all the gases mentioned above. The complication tht im facing rite now is that my GC is a single column single dimensional chromatography system therefore im hoping for a single column to all those mentioned above..

Mr Matthew, could u explain more when u mentioned that i will be flow restricted when using TDC or a HID?

Mr Rodney, There is no Oxygen or Nitrogen in my sampling..

[kellylen1412]

I have a TCD Dectector which i was made to understand is sufficient enough to detect all the gases mentioned above. The complication tht im facing rite now is that my GC is a single column single dimensional chromatography system therefore im hoping for a single column to all those mentioned above..

Mr Matthew, could u explain more when u mentioned that i will be flow restricted when using TDC or a HID?

Mr Rodney, There is no Oxygen or Nitrogen in my sampling..

[AICMM]

kellylen1412,

Sorry for the confusion. You will NOT be flow restricted by the use of the TCD or HID as contrasted with the low flow rates required by the MS. Therefore, you are able to use packed or micro-packed columns with their requisite higher flows but you can use larger loops to get more material on column. The TCD is concentration dependent so you don't want to overdo it but you can use 10-20 mLs/min and sweep a 1 mL loop in 3-6 seconds to get good peak shape. You will detect all of the gases you listed but your detection limit for hydrogen will be pretty poor since it has a thermal conductivity close to that of helium. Hope that clears things up.

Best regards.

[kellylen1412]

Thank You Mr.Matthew for the clarifications. But still im kind of confused on the selection of the column. Before this i was about sure on using capillary column but now im reconsidering since your suggestions of trying packed or micropacked column. Im quite new in this field and guidance are sincerely appreciated.

Is it possible Mr. Matthew for you to recommend me a specific brand of column (packed or micropacked column) that is able to do the above mentioned?

Wht about capillary column? is there any disadvantage of using it?

[chromatographer1]

The real issue here is what detection limits do you wish to meet?

Are you interested in measuring accurately 1%, 1000 ppm 100ppm or 10 ppm or even less?

If you are interested in measuring 1% then perhaps a capillary column will suit you. BUT You may not be able to measure hydrogen using helium carrier at that level and lower levels are not possible.

Perhaps you wish to measure several percent of hydrogen, well, there is a problem: the response will NOT be linear, and it will even reverse as the concentrations change.

These issues are why I suggested you talk so Supelco Technical Service. It is free and you will receive very valuable advice AT NO COST.

If you wish to measure these inexpensively, then I would repeat my suggestion and ask you to use a porous polymer column, micropacked (1mm ID) for very fast analysis, and packed (2mm ID) for conventional analysis.

If you wish to measure hydrogen accurately you must use argon or nitrogen for your carrier, but the sensitivity of the other components may not be acceptable.

You need to do additional evaluation before you spend your money the first time. Good luck and best wishes,

Rodney George
Supelco