Revalidation required if FID temperature changed?

[kedar.pat]

Hello!

Do we need to revalidate a method if only FID temperature is increased (say from 250 to 300) to increase the detection limit. I am not able to detect Benzene in ACS method for solvents at 50ppm level, but if I increase the detector temp to 300, I can detect Benzene easily (less than 2ppm also). Do i need to revalidate the method? Everything else is same.

[Peter Apps]

The change made a difference to method performance - a very unexpected change that suggests something strange going on with the method, so a validation might be a good idea.

Peter

[kedar.pat]

Thanks Peter Apps.. Changing the temperature will change Limit of Detection that's why I am confused. I searched some other websites for the same. I found what is acceptable and to change without validation in USP & EP and when you have to validate. But i couldn't find anything mentioned about FID temperature.

[Consumer Products Guy]

I'm just surprised that FID temperature of 200C will not detect benzene, but 300C will.

But I believe you. And I wonder why ACS scientists had FID so low. I cannot remember us EVER having an FID temperature so low, even when we did toluene at 40C oven temperature.

I'm not an expert in validations, felt we went overboard on most of ours. But I agree that you should document something. Robustness testing would help determine on your system what minimum FID temperature for you should be.