Chromatography Forum

Hi,

I want to use a 490 micro GC to measure a gas mixture in continous operation but i donw know how to do it. Up to now, I've only used discrete sample injections and I dont know what it is necessary to analyze composition changes of a continous flow with time. In using Galaxie software.

If anyone can help me or tell me any reference how to do it I will be very pleasant.

Regards

It is far too complicated a question to be able to give you an answer with the meager details you have offered.

It is like asking: " I want to bake something. How long and how hot do I need to keep the oven. "

If you can give some details and limits to the gas stream you wish to monitor then perhaps someone can begin to give you a good answer.

best wishes,

Rod

The final purpose is to measure a gas mixture from a gasifier: H2, CO, CO2, CH4... Before to do this, I want to try some other analysis of my system but I want to know the composition in real time and know the consequences if any operation parameter is changed. I don't know what more to explain. It could be only air I want to analyze the composition with time rather than discrete samples. It doesn't mind the type of gas or the method parameters (I've already had them), it's just to know how it can be done and later I'll choose what I want to "bake in the oven".

I've read that it is possible to do this with a 490 Micro-GC but in the technical information of the equipment and the software I've found nothing.

Thank you very much. Regards

..., it's just to know how it can be done ...

Or rather why it can't be done

If you wish to use a GC you can monitor a gas stream only by taking discrete samples. Such a machine is called a process analyzer.

To get a continuous measurement would require another type of instrument such as a spectrometer, be it IR or UV, but you would only be measuring a continuous content of probably only one component of the gas stream.

Good luck with your project and let us know of your progress.

best wishes,

Rod

vaidostradas,

So, Galaxie was probably my weakest subject in school ;>).... But, generically speaking (and functionally you could do this with EZChrom) can you set up a sequence in your software? If so, tell line 1 to run sample 1 ninety nine times. Then tell line 2 to run sample 1 ninety nine times.... This is how a customer of mine makes their Agilent do continuous stream injections.

Keep in mind, chromatography is a digital event, on or off. Not analog since you have to allow the GC to elute the sample from the column over time. Your data rate is always restricted to the run time but with a micro this is only a matter of minutes so that's pretty good. You'll miss fast transient events but if your system is producing large quantities of gas as fast transient events, you have other problems, not the analysis.

Best regards,

AICMM

... since you have to allow the GC to elute the sample from the column over time. ...

That is the right answer for question "why not possible ?".

Thank you very much all of you. My first option was to programme a sequence but I thought another solution was possible. As you say, it is a discrete event that need some time to analyze, so it's not possible to measure continuosly. Then I'll use the sequence option.

Thank you very much!!!!