FET Concentration in HS

Discussions about GC and other "gas phase" separation techniques.

3 posts Page 1 of 1
I am currently using a full evaporation technique (FET) and inject the headspace using an ITEX method I have developed.

I have a 1000ppm solution in water. I am taking 50ul of this solution into a 20ml headspace vial and evaporating using an agitator set at 150 degree C.

How do I work out what the concentration of this will be in the gas phase when fully evaporated?

Thanks,
Rebecca
Since it is fully evaporated, isn't it as simple as

1,000 µg/mL x 0.050 mL = 50 µg

in the vial? What are the remaining details of your method? Are you pulling all of those vaporized molecules through your ITEX device and trapping them on a sorbent? I'm not an authority on the ITEX device/technology but it looks like a variation on the theme of thermal desorption.

I'd say your calibration curve is likely going to be some plot of mass of analyte correlated to instrument response. Once you know the mass of your analyte in the unknowns, you'll calculate the concentration in the sample from the amount of sample you vaporized in the first place.
No need to calculate the HS concentration. Derive your calibration in terms of the concentration in the liquid phase, keep your volumes constant and you won't ever need to know the actual gas phase concentration.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
3 posts Page 1 of 1

Who is online

In total there is 1 user online :: 0 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm

Users browsing this forum: No registered users and 1 guest

Latest Blog Posts from Separation Science

Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.

Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry