[am00120]

Please could you help me to identify cause(s) of peak that appears around r.t.15 minutes in my GC-FID chromatogram. I use ISO method for testing indeks of mineral oil/ water quality. I have problem with this one peak that appears around 15 min, method run is about 22 +10 for cooling. Initially I thought this peak was due to water presences but don't think so, it might be slightly brouder when little bit of water is present but don't think is due to water itself.I dried florisil, sodium sulphate, chromatographic column. I clean column, evaporator, checked for contamination in working extrahent, heksane. If the signal sample is high, so the peak is giving false high result. I would appreciate any tips and help.
Many thanks.
Anna