Chromatography Forum

Good afternoon, dear colleagues.
Sorry for may be easy question or the wrong question. But for this, and there are forums, is not it?;)

Help me please, I find the optimum mix of compounds for the GC separation. It is necessary for the internal operations in the laboratory.

so, I decided to examine the next question:
I understand that the best compounds for the GC - a volatile, low molecular weight and don't high polarity (PAH, ethers PCBs).
But I did not once meets with the data, which also affect such an indicator as the LogP. Tell me please, what is the physical and chemical values you use to confirm the detection of compounds in the GC or HPLC?

May be logD, pKa, Polar Surface Area or Polarizability may be...

I select pesticides.
It's easy to see the article and just believe it, but it is interesting to find an answer and have a theoretical experience.

With best regards
Dmitry

I hope not to sound harsh, but I do not really understand what you want to ask

Tell me please, what is the physical and chemical values you use to confirm the detection of compounds in the GC or HPLC?

You run a sample of a known substance and a known amount and get a peak at a certain retention time. You then compare that peak to your sample which should also elute at the same time.

Another way to confirm would be by using a mass spec detector.

You can also confirm identity by using separation by a different polarity column which will give different retention time orders. For PAH by LC I use both UV and Florescence detection to confirm the identity of the analyte.

Other properties would be good if you have a pure substance that you are working with, including boiling point, melting point, refractive index, IR spectrum and such, but so often most of us only have trace amounts to work with and need to use variations of separation and detection techniques.