Chromatography Forum

We Have the Mass of Waters Inc. with masslynx Software.
My problem is when we injecting the samples or water or methanol or Acetonitrile we got the strong signals of M/z 69 and 113.
in complete procedure we are not using any kind of buffer and TFA.
but my R&D personnels saying that this is the mass of Trifluoro Acetic Acid.
is it possible

Without a bit more detail, it is hard to rule anything out. There is no indication of the history of the instrument or the conditions in which it is being used.

In our Previous Experiments we used TFA as Buffer( 0.1%), but after up to three days we clean the Mass lines with water , MeOH and Acetonitrile.
After that we injected the saqmples and we got the mass in water , MeOh , acetonitrile and also in Samples where due to presence of these mass the interpretation is not clear whether these are from samples or from systems.

this probably won't help much now, but it's generally a good idea not to use TFA in LC-MS if you can possibly avoid it. In most instruments, for electrospray, it badly reduces ionisation efficiency and leads to very poor results. Nearly always a simple substitution of formic acid for TFA will improve a method from the mass spec point of view, without totally messing up the chromatography!

Once you use TFA in a system it is going to show up regardless of what your mobile phase is. Even a cleaning of the system may not get rid of it all.

Alp

Do you see TFA if you only infuse? Do you use an on-line degasser? The later generally has been shown to adsorb perfluorocarboxylic acids and release them slowly. Other parts can be cleaned much easier.