By Marky on Wednesday, August 18, 2004 - 09:47 am:

Hi !

I´m treating a single Quad LC/MS System of Agilent. In the last time I have really problems
with total ion current chromatograms. My tunes are awful; I have a dominant impurity of m/z=214.
I really don´t know where it comes from. Since one week the service technican ans me try to find out what the reason is for this impurities. We replaced parts like capillaries, seals, transfer capillary in the MS-part, corona needle, APCI-Heater and so on.
Now we constructed followling adjustment: We are pumping the liquid (MeOH) directly from the reservoir (bottle methanol) into the MS (no connection with degasser, autosampler, columns oven, column). The TIC has abundance of 2 million (gain 1, scan m/z: 100-1000). Then we changed the Methanol (From MERCK to BAKER; both HPLC gradient grade)and the TIC is decreasing. We think that maybe the methanol of MERCK is not OK.

Does anybody of you has an idea what the impurity m/z=214 is, where it comes from or does anybody of you has similar bad experiences with MERCK Methanol in LCMS applications.

Please help me I´m really desperated.