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Topic: Measuring the concentration of components in a gas sample using GC  (Read 4250 times)

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Offline kinetic

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Hi,
I want to measure the concentration of Benzene (C6H6), Cyclopentadiene (C5H6) and Cyclopentadienyl radical (C5H5) in a gas sample using GC. I have a column that can be used for measuring C1-C6 and the standard gas mixture of C1-C6 (100 ppm each) as well. Can I measure the concentration of the mentioned components in my sample with the column and the standard that I have?
Thank you

Offline Stepan

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Re: Measuring the concentration of components in a gas sample using GC
« Reply #1 on: July 06, 2011, 06:40:44 PM »
Not sure about C5H5, but the rest is quite simple to analyse.

My lab does it on commercial basis: http://www.labconserv.com/pages/iaq.html or http://www.lcsairtest.com/laboratory.html.

You are limited only by your detector and injector configuration. You need a FID or PID detector on GC. If your concentrations are 50 ppm and above, you can test gas by direct injection of the gas (0.5-1mL). For better sensitivity you need to concentrate the sample.

The lowest achievable sensitivity is about 1-3 ppb

Offline kinetic

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Re: Measuring the concentration of components in a gas sample using GC
« Reply #2 on: July 07, 2011, 05:08:10 AM »
Thank you for your help,
My sample is in gas phase mix of C6H6, C5H5 and C5H6. Can I use liquid standards for analyse?

Offline Stepan

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Re: Measuring the concentration of components in a gas sample using GC
« Reply #3 on: July 07, 2011, 07:57:22 AM »
Yes, if you have enough gas (1L and more per sample)

you can collect known amount of gas on charcoal tubes. Extract you vapours with CS2. and analyse them as liquid samples. In this case you can can use liquid (in CS2) standards for calibration. (see picture http://www.lcsairtest.com/laboratory/benzenea.html)

If you work with less than 1L of gas it is better to use gas injection and gas calibration.

Offline kinetic

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Re: Measuring the concentration of components in a gas sample using GC
« Reply #4 on: July 07, 2011, 10:40:46 AM »
Thank you, it was really helpful

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