Quaternary ammonium cations chromotography

[WilliamHeesen]

Hi, my name is William

I am currently an intern at a company and I am tasked to optimise the method of the chromatography of quaternary ammonium salts on the LC-MS/MS.

Thus far I ran the method with a standard from 50ppb to 1 ppb bith the components = DAC 10, DAC 12, DAC 14, DAC 16 and DDAC.
DAC = Benzalkonium chloride
DDAC = Didecyldimethylammoniumchloride

I performed a triple standard to figure out how good the linearity was, for 3 of the 5 components the results were fine with a R2 value above 0.98, but the results of DAC 10 and DDAC were poor and showed a linear line that started very high on the Y axis and ended up slightly higher on the Y axis. A colleague thought it didn't dissolve properly but since this was the exact same result for all three standards this cannot be the case, we then though the samples were possibly contaminated.

Now i have found out that this method can also be run on a HPLC instead of a LC-MS/MS. Could this be the problem I am looking for? is it simply performed on the wrong machine?
It could be a contaminated standard, but I have ordered new standards which will arrive and once i get them i can know if the previous standard was contaminated or not.

Would love to hear some feedback on this as the colleagues are not really able to help me any further with this, at least not at the moment.

[richiekichi]

LC-MSMS should be fine for your method.

My first guess would be that you have not correctly identified your peak of interest. Perhaps you are accidentally trying to quantify a component of your mobile phase or standard solvent.

Also check that your quantification software isn't trying to correct for a internal standard (if you're not using one).

[WilliamHeesen]

LC-MSMS should be fine for your method.

My first guess would be that you have not correctly identified your peak of interest. Perhaps you are accidentally trying to quantify a component of your mobile phase or standard solvent.

Also check that your quantification software isn't trying to correct for a internal standard (if you're not using one).

Thanks for the response, we actually found out what it was though in the meantime, the standard components we were using were not giving proper results, so we ordered new components and theyre running great.