I will analyze a gas stream at high temperature (above 150 deg C) in a GC. But one of the components is liquid at room temperature. We cannot prepare the standard directly for calibration.
The system is methanol, hydrogen and ethylene. I have a multi-gas analyzer with 3 columns and four detectors (2 FID, 2 TCD, methanizer).
Also note that all the components are above 20 mole-%.
How do I calibrate my GC for the system?
Hello,
I would suggest using bubblers. You can pass N2 gas to the input of the bubbler containing the liquid sample and mix the output N2 gas (saturated with your sample) with rest of the other sample gases and send the mixture to the GC. You can vary the concentration of your liquid sample in the gas phase N2 by adjusting the temperature of the bubbler and/or the flow rate of incoming N2 gas. For adjusting temperature you can either use temperature controlled heating tape or water bath. It will require a lot of plumbing, but its doable.
https://openclipart.org/image/2400px/svg_to_png/176381/Waschflasche.png
In the above figure left hand side tube (long one) is inlet of N2 and right hand side tube is outlet of saturated N2.
Good luck
Sambhav
If there is no possibility to produce the gas-mixture at elevated temperatures (above the boling point of Methanol 65 °C), you should think about calibrating your system for methanol separately using liquid injection.
If you have the means to prepare gaseous standards using heated vessels and valving, then simply work above the BP of methanol (and preferably close to your sample stream temperature), and treat the methanol vapour as if it were a permanent gas.
First question: do you have any gaseous standards for hydrogen and ethylene?
You should use only TCD, that can detect all of them together. FID would never detect your hydrogen.
If you can measure your detector response for every component, even if you can only inject them apart from each other, you could quantify the mixture. If you normalize every area for the same dector response - you can choose any of the substances as your 'standard' - you can convert the areas to their normalized values. Thus the percentage in mass for each substance would be just their percentage in peak normalize area in relation to the total normalized area. The total normalized area should sum all peak normalize areas.
Thanks everyone. I'm planning to use a heated gas sample vessel for injection. I'll then use TCD for hydrogen and FID for HCBN. Thanks again.
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