Chromatography Forum

Hello all,

I am currently working on a Micromass ZMD mass spec instrument which is an "Open Access" instrument within my department. Due to this, people have been using the instrument with a blatant disregard to correct mass spec knowledge which has caused an unknown contamination with the most prominent peaks at m/z:

42.1, 67.0, 85.1, 105.1, 135.0, 145.1 and 213.2.

Does anyone know what these peaks may be and, more importantly, know of an effective wash protocol that would get rid of these peaks with minimal "down time" as the instrument is needed frequently to many in the department.

Many thanks,

Pete (and Yana)

Pete and Yana,
Ions like to 42, 67, 85 and 105 are often to found in MS instrument. You must to clean the API source at the end of each working day (or more often if you suspect they are contaminated) by flowing a 50:50 methanol / distilled water solution from the LC through the API source.

If you need more information, write to me.




Alejandro

Thanks Alejandro, we have cleaned the API source many times and there has been extensive washing with relevant MeOH:Water solutions. The capillary was also exchanged for a new one. The ions present were abundant and a TIC of e7 counts was observed for these. Not normal!!

Many thanks again for your suggestions, but it may be of interest to know a soil sample was analysed recently and may have contaminated the instrument. A wash of 50:50 iso-propanol:toluene was used after this experiment with little or no help. Any ideas???

Thanks,

Yana & Pete.

With this situation, you must to open the ion guide (before to quadrupole) and clean with MeOH and ultrasonic bath.

I'm sorry, good luck

If you haven't already, I recommend you make sure the contamination is not in your LC. Disconnect your LC and, using a clean syringe and clean tubing, infuse blank solvent (or a known pure standard) into your MS and see if you still see the background ions. If you don't, then the focus should be on cleaning the LC.