Hi Everyone,

I've been processing sea water samples with the SPE technique in order to extract a few of parent PAHs.

I've used Sep-Pak C18 3cc SPE cartridges 500 mg (Waters), which were washed with DCM, dried out completely, then they were conditioned with methanol and then with 40% methanol solution, the sample was loaded, the cartridge was rinsed with the MiliQ water, dried out with the N2 and PAHs were eluted with DCM. Next the extracts were dehydrated with Na2SO4 and concentrated with a nitrogen evaporator.

After the analysis on the GC/MS system, the chromatograms show the targeted peaks and they also show a huge peak of something I didn't expect to see and which contaminates our system and harms the detector.

My question is if anyone has ever had this problem? The link below will send you to the mass spectrum of this unidentified compound. The NIST library's suggestion (probability ~92%) is 1-Dichloromethyl(dimethyl)silyloxy-10-undecene :shock:
If it has dichloromethyl- and siloxy species, is it possible that the SPE cartridge has been damaged by the DCM, reacted with it and started producing by-products? I have tested many SPE cartridges and many solvents in the method development step and never had this problem. Does anyone have a clue what might have happened there?

I would really appreciate suggestions and comments. Thank you!

Cheers,
Kathy

https://drive.google.com/file/d/1DO483F ... sp=sharing