Chromatography Forum

Hello everyone!

I am developing a method for plasticizers with LCMS and I keep getting large peaks in my blank, even in “No injection mode”. I suspect the plasticizers are in my mobile phase, because the longer I equilibrate the system, the larger the peaks.

I keep getting the peaks with bottled water, so I m having trouble tracing how they got into my mobile phase! Has anyone found plasticizers in bottled LCMS water? Can anyone help with this kind of contamination?

Are you using LCMS grade purchased water? If so it should be lower in phthalates than normal HPLC grade water.

Plasticizers can also come from organic solvents if they are not the highest grades, or any polymer tubing being used in the system.

If they require higher percentage organic to elute and are coming from the mobile phase or pump, you can place a guard column between the pump and autosampler to act as a delay column which will trap the unwanted analytes and delay their elution until after the injected standard analyte elutes from the column, this is used for PFAS/PFOA analysis to keep these teflon precursors from pump tubing and seals from interfering with the analysis, it should also work for plastizicers.

this isn't going to help... but plasticizers are in absolutely everything. The office carpet, the chairs, the tubing, filters, filter housings, any solvent that's ever been in the same room as any of the above... it's truly horrendous trying to get a sample of anything without a plasticizer peak of some sort or another. A few years back I was asked to certify that I don't use any plasticizers in the lab. I had to reply that I don't buy any plasticizers, but I use them daily as a mass-check. Good luck!

this isn't going to help... but plasticizers are in absolutely everything. The office carpet, the chairs, the tubing, filters, filter housings, any solvent that's ever been in the same room as any of the above... it's truly horrendous trying to get a sample of anything without a plasticizer peak of some sort or another. A few years back I was asked to certify that I don't use any plasticizers in the lab. I had to reply that I don't buy any plasticizers, but I use them daily as a mass-check. Good luck!

Puncture a septa on the autosampler vial and wait a while and shoot it again, you will see some there as well. About the only option for that is solid PTFE or maybe Polypropylene caps but those don't reseal after being punctured.