Chromatography Forum

Hi there. May I know if there is any methodology to analyse xylene using LCMS/MS? I knew that xylene (PAH) is normally analysed using GCMS. However, we're trying to identify xylene using LCMS/MS.

If there is anyone here who can help me out here, it will be greatly appreciated. Thanks a lot.

APPI or APCI might work.

I do not see any ionisable function in the molecule and a quick literature search didn't reveal any LC-MS methods so it should be quite difficult to get any appreciable signal (even with APPI or APCI in my opinion).

I guess the only way you could do it is through adduct formation by using the appropriate metal additive (i.e. Li ? or something like that). Not an easy route though and problematic when trying to be quantitative...

Thanks guys !!! We have found a paper that analysed on the PAHs but not the xylene molecule using APPI/Photospray source.

As mentioned, I think most probably we will need to make an adduct formation for the xylene compound.

Hopefully, we can do it and then we can share the information for future reference.

Hi there. We have the xylene std and the xylene sample and we're going to quantitate the amount of xylene in the samples.

May I know what is the best derivatization for such compound? We're trying to derivatized it into an amine compound but we would like to have other opinions in this matter.

If you have a suggestion on how to derivatize and quantitated it, please let me know. Thanks a lot.

Why one earth are you trying to do xylene by LC-MS ???

Peter

Hi there. Yea, its strange way to do things over here. We're trying to access the differences between using a GCMS and a LCMS/MS to analyse that compound.

Xylene is found to be a contaminant in the sample matrix that we're analysing; so we would like to know what is the level of contamination from xylene (quantitate) it with the LCMS/MS; not with the usual GCMS method.

Any idea? Thanks a lot.

Hi there. I am going to derivatized the xylene compound to a nitroso xylene compound ie 4-nitroso-m-xylene.

Is there any ways that this can be analysed via LCMS? Or do I have to derivatized it and replaced the nitroso grouping to enable the compound to be more ionizable?? FYI, I dont intend to do oxidation on the xylene compound because it involves the usage of bio-catalyst/perioxidase which we dont have in our inventory.

Please advise. Thanks.

I am not an LC-MS methods person so I can't help there.

However, I wanted to point out that xylene is not a PAH. PAH is polynuclear aromatic hydrocarbon (It is also called polcyclic aromatic hydrocarbon and PNA (Polynuclear aromatic). The smallest PAH is naphthalene (followed by anthracene and pyrene). Xylene has only the one benzene ring. So it is not classified as a PAH.

So if you search for PAH analyses, you may not find xylene listed as an analyte. It would be better to search under solvents or for xylene itself.

Not sure if that helps you in your literature search, just wanted to clarify the structural differences.

Regards,
Dan

Also having little experience with LC-MS, I have a somewhat "academic" question: Why would xylene be considered difficult to ionize? In conventional MS one wouldn´t even think about an inability to ionize it, except maybe in a nightmare. Is it the competition in LC-MS? Or, are the ionization voltages much lower in LC-MS?
Now if LC-MS poses such a problem why not do MS off-line ("normal" MS after the chromtography)?

The nitroso-xylene coumpound certainly would give better sensitivity than xylene itself. Sounds like a very strange way to do it though, SPE or liquid-liquid extraction into a solvent and GC/MS would be the best way to look for xylene in a water sample.