Chromatography Forum

I have a question on ghost peaks - I have read several articles related to the subject and while I'm surely not an expert on this I am intrigued by a common factor in our laboratory: why these ghost peaks are always at the retention time of the main peak, in some cases even appearing from a setup where the API has not even been involved.
In at least three products a 'ghost peak' was attributed to swab leachate. But I reason what is the probability that a compound being leached from a swab elutes at the same RT as the main peak, for 3 different molecules with totally different methods.
We have done the usual checks for carry over, late eluting peaks and gradient false peaks.

Do you have any suggestions or reading material I can visit, or maybe you need more information?

Hi Flying Arrow,

What it sounds like to me is that you guys don't have a ghost peak. If on three different samples, with three different methods you have something eluting with your compound every time, I would figure that the issue is not a ghost-peak and is actually involved somewhere else. If for every injection you perform the product elutes with an impurity, and this occurs with different samples, I'd assume that it came from somewhere up-stream like within your sample preparation or perhaps mobile-phase preparation. Whatever this contaminant is does it decrease with increasing washes, have you seen it increase upon injection? When you run the column with blank injections do you still see the ghost peak and/or is it depleting? Perhaps are you running an ionizable sample and you have an ion-pairing reagent that is attached to your analytes? Sorry I couldn't narrow this down further for you but hopefully someone will come along with a more concrete solution.

Tyler