Chromatography Forum

Hello. Apologies if this topic has already been discussed (I could not find).

I wanted opinions regarding the need for an LOQ injection for routine system suitability for GC methods.
Currently, the methods we are running do not include an LOQ injection. However, the LOQ is evaluated/established during method validation.

There is debate among my colleagues whether an LOQ injection is required for routine system suitability for GC methods. For residual solvent methods (our standard solvents usually have a limit of several hundred to several thousand ppm), I do not see the need to inject an LOQ solution routinely for system suitability.

What is your standard practice?

Thanks!

Hello

System suitability test for chromatography methods usually includes accuracy and precision test (sometimes resolution). LOQ is part of method validation so in my opinion for routine system suitability (daily) accuracy and precision test are enough.
Of course it is my personal opinion but it is interesting how it works in different labs.

Regards

Tomasz Kubowicz

To me, unless you're working near the detection limit, there's no point in worrying about your LOD or LOQ. I worked in the pharmaceuticals industry years ago and we were a QC lab - mostly worried about drug stability. Our samples never came close to the low-end of detection. We never had a "LOQ Standard" as part of our suitability criteria because we'd never come close to that.

It looks like in your situation it's really a waste of time because as long as the residual solvents are less than what I assume from your post is an easily detectable amount, you don't care. I'm with you. Don't bother!