Where do these peaks come from?

So I see you say your method is a split method 1:1 (so 50% of sample goes through). Is there a reason for you to not use splitless and do injections of 1uL instead?

Also, your liner looks to me like a liner I would use in a splitless method and not splitless unless you have the cross gold plate in your inlet instead of regular gold plate. Also, what is the pressure of your inlet with that flow?

So you say it is not part of your ACN injections but it is part of your sample, and you say you are looking for impurities in your sample. So is the issue that it does not seem to be linear with the concentration of your samples? If so, if it is not part of your ACN Blank injections, are you sure it is impurities from the sample and not something like sample degradation from high temperature of the GC?

So I see you say your method is a split method 1:1 (so 50% of sample goes through). Is there a reason for you to not use splitless and do injections of 1uL instead?

Also, your liner looks to me like a liner I would use in a splitless method and not splitless unless you have the cross gold plate in your inlet instead of regular gold plate. Also, what is the pressure of your inlet with that flow?

So you say it is not part of your ACN injections but it is part of your sample, and you say you are looking for impurities in your sample. So is the issue that it does not seem to be linear with the concentration of your samples? If so, if it is not part of your ACN Blank injections, are you sure it is impurities from the sample and not something like sample degradation from high temperature of the GC?

Thanks for taking the time to reply. I am not sure why the injection is split and the liner was chosen. Is there a liner that you would recommend? But when using a splitless injection and 1 uL injection, those peaks are still present.

The peaks are not linear with sample concentration (i.e. 10x sample concentration results in 3x bigger unknown peaks). All other impurities present behave as expected with varying sample concentrations.

The peaks may be from sample degradation in the inlet but the real mystery is when I injected just hydrogen peroxide and ACN (as part of a degradation study) and saw these same peaks. This made me think that there is some kind of reaction with an inlet material in the presence of a sample. GCMS data was inconclusive.

If you want to try Agilent's deactivated liners, this is a part number for it 5183-4693. These are for splitless injections. Also we have deactivated split/splitless inlet that you might want to look into if that could interest you if these are reactions with something in the inlet, if it is strictly liner then just a change of liner should fix it, but I cannot say what is creating that issue. I am not aware.

If the peak increase with temperature, I would suspect there is a degradation or a reaction of some kind in the inlet that is happening for sure.