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How do you Deduce what Compounds are in a mixture by HPLC and GLC?

Hi guys, I don't really understand how you can deduce what is in an unknown mixture from HPLC and TLC. It dose not help that my textbook does not explain this. Thanks! =)
Original post by ΘTheta
Hi guys, I don't really understand how you can deduce what is in an unknown mixture from HPLC and TLC. It dose not help that my textbook does not explain this. Thanks! =)


You cannot deduce them, you can only separate them.

If you run possible known compounds then you will see a trace at the same Rf value.

Alternatively you can compare the IR spectrum of the eluting compound with a database of spectra.
Reply 2
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ΘTheta
OP
10
Original post by charco
You cannot deduce them, you can only separate them.

If you run possible known compounds then you will see a trace at the same Rf value.

Alternatively you can compare the IR spectrum of the eluting compound with a database of spectra.


Thanks for the response.
But I don't really understand by the underlined. Can you please explain. =)
Original post by ΘTheta
Thanks for the response.
But I don't really understand by the underlined. Can you please explain. =)


You inject a sample containing substances that could be in the unknown and record the retention times. If they coincide with peaks in the unknown then you have a possible match. It's not definitive. It is better to fingerprint with IR.

GC is often combined with MS to give identification.
Reply 4
Avatar for ΘTheta
ΘTheta
OP
10
Original post by charco
You inject a sample containing substances that could be in the unknown and record the retention times. If they coincide with peaks in the unknown then you have a possible match. It's not definitive. It is better to fingerprint with IR.

GC is often combined with MS to give identification.


So if the recorded retention time are similar to know retention time in a database, then you could have a match is what you are saying?
Thanks
Reply 5
Avatar for Borek
Borek
4
Original post by ΘTheta
So if the recorded retention time are similar to know retention time in a database, then you could have a match is what you are saying?


Yes, that's the idea.

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