apci tuning issue & nebulizer needle and ferrule connection

Question

Hi. Our lab has a HPLC/APCI-MS instrument running for couple of years. Recently, the tuning became an issue - no peaks coming out but noise. Usually after changing the APCI tuning mix, flushing and after 2-3 of dual tuning came out okay. 
 When I check the nebulizer spray it looks fine. 
 So I thought the nebulizer needle was corroded so decided to change it. But then I thought the old nebulizer needle should be compressed by the ferrule at the end of the needle holde it but it was loose and the needle came out easily. Does this mean the old needle wasn't compressed by the ferrule? Can this cause the issue? 
 I would like to ask if anyone had this issue or advise. Thank you.

dannymobbs · Accepted Answer

The nebulizer needle should be held in place by a compressed ferrule but as you said the spray was good, the loose grip of the needle is unlikely to be the cause. So, a no signal problem could be any part of the MS but you did the right thing by starting with the source. Did you also change the corona needle? Does the spray shield look very dirty? Perhaps that needs a clean? When was the last time you cleaned the capillary? Sorry for more questions than answers, but this type of problem could go in many directions...

dannymobbs · Answer

It&rsquo;s definitely worth trying to clean the capillary. I attach here the printed instructions from the animation contained on the Resource Guide which ships with the instrument. The Alconox powered cleaner referenced is part number 5190-1401. Pay attention to step 3 - keep the concentration as stated. Also - step 10, take this as gospel - do NOT sonicate in Alconox for more than 15 minutes. Finally - be fastidious with the cleaning (of the measuring cylinder and of course the capillary) with water after the Alconox treatment. Any remaining detergent will cause problems. Once it is clean you can gently blow out the capillary with a clean air stream or let the capillary stand upright on a clean paper towel. Then you can reinstall the capillary and pump the MS down.

dannymobbs · Answer

The 'drying gas pressure control timeout (1401) suggests that you don't have sufficient nitrogen pressure at the MS. You need 80-100psi. If the gas pressure on your generator (or at the regulator if you are using 'house' nitrogen) is set correctly, then it could be a clogged gas filter - the grey cylindrical fitting between the gas supply and the MS. This is a consumable and needs replacing periodically. 
 Also, I only see that error on the 18th March. The entries from the 22nd do not show this error - do you still have problems? Can you turn on the MS? If yes, can you tune?

dannymobbs · Answer

Ok. So it sounds like some progress to get the negative mode tune to complete and look ok. I would run the negative tune only. Let it complete and save the tune file. Then run a positive polarity tune immediately. 
 If that fails again, its probably worth logging a service call since there could be a voltage missing in positive polarity that's working just fine in negative.

dannymobbs · Answer

No worries - good luck with capillary cleaning. Just take your time and you'll be fine. Small correction to my last text - please replace '...or let the capillary stand upright on a clean paper towel' with '...or let the capillary stand upright on a lint free cloth '. Non lint free items shed particles which could get sucked into the manifold. My apologies...

dannymobbs · Answer

Hi, 
 1. The scratch is created by the canted coil spring which sits inside the capillary cap. Its certainly not ideal that this 'band' is present but the ultimate test will be if you observe ions in the tune (which were missing before) and then if the tune goes to completion with the correct mass axis calibration, peak widths and adequate abundances. However, I think you should be prepared to replace this capillary with a brand new one. 2. If the system pumps down normally then the source will heat up and the quadrupole will heat to 100oC. The MS requires nitrogen to be flowing in order to go ready so the fact that you saw the MS in the ON state is good so far. An overnight equilibration is recommended - you did the right thing to leave it overnight (see 4 below). 3. Red normally means error, but we would need to see the logbook to comment. If it happens again, go to the Method & Run Control view. Then go to the View menu item then Logbook > Current Logbook. Attach a screen shot here clearly showing the error message. Do the LC modules also go into the error state. 4. When you vent the MS to do maintenance (or for a lab shutdown), a thermal equilibration of at least 11 hours (overnight) is a must, once pumped down, before you tune. 5. You can leave the LC modules off while the MS pumps down then equilibrates. 
 Hope this helps....

apci tuning issue & nebulizer needle and ferrule connection

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