What is the reason when gcms shows two mass spectra when injected one compound?
Answers
. Among others compounds, early eluting methanol, acetonitrile can form droplets after injection, rather than distributing ideally into the capillary film, which can cause mulitple peaks. Reduce injection volume and change temperature of injection port to study the effect. Less injection may already help.
2. Stereoisomers might be separated by the GC column, often observed for sugars, derivatized by oximation into syn and anto isomers, which can give 2 or even mutliple peaks with identical spectra. Check your protocol and compounds for such potential effects.
3. To heavy sample overload can cause a contamination of your injection system (liner, port pTV sampler, etc.) so that compounds will contaminate into subsequent injections. Replace liner and inject blank sample with only solvent to check.