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### Topic: First GC problems  (Read 3718 times)

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#### Synnr01

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##### First GC problems
« on: October 21, 2009, 10:59:58 AM »
Hi
I did a practical on gas chromatography (determination of fatty acid profiles for two cooking oils by gas chromatography) two weeks ago and now has come the time to write it up and complete certain tasks with the results. However I have a few problems.
I am attempting to calculate the DRF for the components present in my chromatogram.
The formula for this is:
DRF = (AX)/AIS)*(CIS/CX)
A being peak area and C being concentration.
X being analyte and IS being internal standard.
I have the peak areas however I am unsure of the concentration of either.
My chromatogram states the mass of the IS and of the oil used as 260.3 mg and 493.7 mg respectively.
I do know how to work out concentration, however I don't know the volume that that mass is in.
Sample volume is 1 µl but that's not it, surely.
Help would be much appreciated.
Quote from: this is the method
Thanks!

#### Synnr01

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##### Re: First GC problems
« Reply #1 on: October 22, 2009, 06:15:32 AM »
please. Any idea what I need to do??

#### marquis

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##### Re: First GC problems
« Reply #2 on: October 23, 2009, 08:30:10 PM »
Can you define the DRF?  It looks like a response factor, although I'm not sure what the "D" is for.

A couple of other questions.  It looks like your internal standard is the pentadecanoic acid.  Is this correct?

Your calibration may have been done with identical volumes, in which case a volume calculation may not be needed.  Here are a couple of questions.  You put in 511mg of olive oil and got out how much?  You put in 195 mg of pentadecanoic acid and got out how much?  How do the final weights of the unknowns relate to the amount put in originally?

A starting point.  Lets see where it goes from here.  Good luck.

#### chiralic

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##### Re: First GC problems
« Reply #3 on: October 24, 2009, 01:22:27 PM »
DFR means Detector Response Factor

Chiralic

#### Golden_4_Life

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##### Re: First GC problems
« Reply #4 on: January 07, 2010, 03:40:09 PM »
Suggest just using RF "response factor"---the use of "detector response factor" is a bit superfluous given that we all know that the Detector is the component of the system doing the "responding".
Golden4Life