Chromatography Forum

I run a standard 2 months ago and I measured an area on FID (with 60oC temp of the column. Yesterday I run the same standard with 100oC temp of the column and I measured much less area. Is this normal or the sample has decomposed?

Did you use freshly prepared solution(s) for your analysis yesterday?

Or is it the concentration of your analyte(s) very low, so the increase of the temperature can change the peak area little bit, due to the bigger noise at elevated temperatures? The integration of the small peaks could not ensure reproducible peak areas

Or you might have problem with your column, or the other critical parts of your GC system. Check for leaking!

Do you use headspace analysis or direct injection? If you're using headspace check your vials, whether thay are tightly closed or check your connecting parts on your transfer-line.

Also other reasons could be responsible why you're getting lower peak areas.
Supply us with further information for the method and instrumentation that you're using

Best regrads

thanks zokitano for your response..

finally, I think the problem was the vial of my standard.. the septum was leaking..