Pollution on LC/MS ESI Agilent 1100

[Provetech]

I've got a pollution on my LC-MS ESI even in direct injection (column bypass) in the positive ionisation: m/z=242 and in the negative m/z=339.
I cleaned the spary chamber an the capillary, even the first skimmer last month but there no amelioration. What can i do more ? must i call the technical support from Agilent ?
Thanks

[MG]

I don't know about 339, but 242 is tetrabutylammonium (M+ ion, since it is already a preformed cation). In columns that have been used with TBA, I have found it impossible to remove. But you still see it without the column. Most likely the problem is not with your mass spec, but with contamination in your HPLC system. As a first step, get a clean beaker of HPLC grade water and flush your entire system with perhaps 100mL. Then get another clean beaker, fill with water, and repeat. Then repeat with an organic such as acetonitrile or isopropanol. Then try your column bypass experiment again (with mobile phase freshly prepared in a clean bottle) and see if contamination is reduced or eliminated. If contamination is reduced but not eliminated to your satisfaction, the next step is to change out the tubing in your LC system. Also keep in mind that any column that was used when TBA was present in the system will need to be flushed for a long time, and even then it may be impossible to remove all of it.

Alternately, there are more elaborate flushing procedures available for removing contaminants from LC systems. For these, consult the manual for your LC system or contact the manufacturer, and they can recommend a flushing procedure.

[Provetech]

Thanks a lot MG, you're right ! i've just learned that my colleague was using products with TBA.... i'm performing a cleaning.
I'll tell you about the result.
Regards