Hello,

a girl in my lab was having problems with area variation in same sample (re-injection) ,she told me that was because she was using a wide liner for splitless injection and if she have used a narrow liner the the variation will be lower.
my question is if you are placing all sample inside the column in a splitless injection maybe the peak height can vary but the area also?if I am injectin the same amount and the FID is ionizing the same amount the area will be the same,no?
Thanks.

If you are injecting the same amount every time, and if all the sample is getting on-column, and if the FID is ionizing the same amount every time the area will be very close to the same every time. Three ifs must be addressed.

Is the same amount being injected every time? Autosampler or manual injection? Volume injected? Syringe in good condition?

Is all the sample getting on column? What is the solvent? Volume injected? Expansion volume of solvent vs. liner volume - is flashback ocurring? What is the sampling time before switching to split mode? Is column position correct? Is inlet leak-free?

Is FID ionizing properly? Try split injection of high concentration to test precision.

As you can see there are many factors affecting precision of splitless injections. One of the common mistakes with non-EPC HP (Agilent) GCs is turning the flow out the split vent too low during splitless injection. These GCs did not do a true splitless injection, so turning the split flow down causes all sorts of issues.

A narrow bore liner does not necessarily improve precision, especially if using a solvent with a large expansion volume.

Have you tried with an internal standard? Maybe you're abled to eliminated the difference from the injectionvolume.