How long has it been in usage? In principle, you always have some losses in ion current because it is not properly captured by the ion optics and that has to end up somewhere, either it's somewhat volatile and ends up in the pumping conduits or it's not volatile at all and ends up on parts within the spectrometer system. So depending on what kind of samples you analyze, it is normal that exposed parts of the mass spectrometer need to be cleaned every once in a while.

For the Quad I used for my PhD work, we used CeO2 polishing followed by rinsing with hot DI water to get the rods clean. The isolating ceramics could be cleaned by sandblasting, we simply lined them up on a thic copper rod for that so they wouldn't fly away.

Hello Jinkyung Lee, I know that too, we always used double distilled water from a system in our lab. There was a bit of white deposit inside the source and also on the "metal pipe" described. I then used HPLC water once, and after just a few hours everything inside was as white as if I had been measuring with double distilled water for a few weeks. I would definitely recommend using LS-MS quality solvents. Or bidest H2O. But the salt concentration in the sample may also be very high, I'm not familiar with these sharp deposits. Under certain circumstances, SPE cleaning of the sample could remove some "dirt" from the injected sample, so that hopefully there will be less deposits. Regards Dirk

Looks like salt crystals of some sort. What is the buffer you're using? Maybe it is too concentrated or not enough volatile?

In addition to the above suggestions; Do you have additives in your mobile phase? Maybe some impurities are being introduced to the ion source via the volatile salt or acid additives you added...

Secondly, sterilize your system by overnight using 70% IPA purging through the whole system (not direct effluent to the source only) to remove any potential microorganism growth (not typical but give it a try). All tubing filters valves and other components of the LC system will eventually be microbial contaminant-free.

Use every consumable as MS grade. Change your phase filter with the new one or at least degas it in an alcohol solution and replug.

Yellow color change may also indicate some microbial growth deposit or alkaline condition-derived oxidation.

Also, be sure about any pump failure and nothing comes from the hardware before putting all the blame onto the water.

Other than misapplication of the non-volatile salt usage, some alkaline HILIC mobile phase applications are typical at carbohydrate analysis using TEA or ammonium bicarbonate and may also cause some column deterioration (e.g. amine or amide phases). Hydrolysis of silica may also introduce some powder-like stuff into the ESI needle and source. These may not be the cases you are struggling with, but I just added a reminder.

I hope this will be helpful...

Good Luck

Emir...

Dirk Siekmeier Have you tried using deionized water? I always thought HPLC grade water is cleaner than distilled water.. Maybe I should try using distilled water!

Andrzej Wasik We normally use 0.1M KPB for sample preparation and 0.1% formic acid for solvents.

Hi Jinkyung Lee, we used the Puridest PD 2 DG still for gettingour bidest Water. Now we buy Water in LCMS qaulity or UHPLC MS. The idea from İsmail Emir Akyildiz are great, cleaning the LC sytem and only use MS grade modifier in the solvent and sample. I don't knew what 0,1M "KBP" is, if ist is a phosphatesalt, then you have maybe found the problem. That could be helpful to find a different buffer https://www.hplc.eu/Downloads/ACE_Guide_BufferSelection.pdf

Dirk

you have to use :

- LCMS grade water and solvents or milliQ water.

- volatile buffer