Help to improve FID GC performance

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

4 posts Page 1 of 1
I have FID GC instrument with column (C1-C5), but i need to make some improvement in these two points
1. The way used to amplify the FID detector signal (micro-volt).
2. The way used to heat the column.
Is there someone can help in such subject?

Commercial GC -FIDs have been around since the 1960s. Their technology is mature, and there is not much room for improvement, especially with simple things like column heaters and standard components like FID electrometers.

If you have a problem with your instrument it is much more likely to be because it is broken than because it is badly designed and built.

In any case we need to know what you are doing, how your are doing it and what the symptoms of the problems are.

Peter Apps

FID's measure pA, not micro-volt. Micro-volt may be the output from the amplifier but they measure current. They are truly amazing detectors (HGF!) so your question is way too vague to do anything with.

Are you using a commercial system or home built?

Best regards,


To be honest, the FID ADC measures voltage got from output of low-current amplifier.

None of the commercial instruments were calibrated with real low-current source (like this or like this to be checked these pico-amperes are real.

So it is a matter of trust of you to the vendor who provide you with pico-amps or mV which is proportional (according to the Ohm law I=U/R) to the current which is proportional to charge actually flown in ionization chamber which is proportional to ionization effectivity of your H2 flame and slightly relate with substance structure.

Also none of the vendors provide you with the feedback resistance (R) in low-current amplifier because in some cases (like Agilent) it is pure virtual thing.

Better take known amount of substance, inject it and get straight or relative response of FID (measured in whatever units).
4 posts Page 1 of 1

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