Chromatography Forum

Hey all,

Writing the brain trust with a technical question. We are donating a Q-Exactive Plus (QE+) to another lab, but I am concerned about their storage conditions.

The lab plans to store the instrument exposed to atmosphere over six months. No vacuum or nitrogen flow entering the instrument. My concern is residual water vapor entering the instrument and corroding the metal parts inside the QE+ (e.g. quadruple, orbitrap) over those six months. Additionally, the QE+ will be stored in the same room that glass cleaning takes place, so any residual humidity will be higher relative to the other rooms in the lab.

To my understanding, the metal used inside the mass spectrometers is selected for its ability to conduct a current (AC/DC) to generate an electromagnetic field (EMF), not resistance to corrosion. So any corrosion that may occur will impact the current and contribute to unequal/turbulent EMFs impacting data acquisition and result in variable data. Considering the application of the QE+ is for cGxP activities in a FDA lab, reproducibility is key.

I sealed the exterior vacuums lines, applied desiccants ~10cm away from the ion source mount under ultra-clean aluminum foil and taped the foil to make a working seal, but I feel this is a stopgap measure and an inadequate solution for long term storage. I advised for the lab to purchase a N2 (>=99%) cylinder and keep the instrument in standby to prevent any instrument damage but they weren't convinced it was needed.

Am I being overly paranoid? I am receiving conflicting information from Thermo tech support so wanted to get some outside opinions to see if I am being paranoid. I wouldn't be as concerned if it were for a few days, or ~three weeks, but six months raised some red flags IMO.

Thanks in advance!

You are right to be concerned about the situation!!!

I would set it up as if you were leaving it in standby over the weekend.

Have at least the roughing pump(s) running full-time; don't pull air through it, just keep it under some good vacuum.

In that damp environment I would also be thinking about possible corrosion of electrical connectors on the outside of the instrument.

Good Luck!!

You are right to be concerned about the situation!!!

I would set it up as if you were leaving it in standby over the weekend.

Have at least the roughing pump(s) running full-time; don't pull air through it, just keep it under some good vacuum.

In that damp environment I would also be thinking about possible corrosion of electrical connectors on the outside of the instrument.

Good Luck!!

Hello JMB, thank you for the reply/support! I will see how they feel about using a forepump rather than N2 cylinder/generator.

Finally, total shot in the dark here... you wouldn't happen to have or know any additional examples/papers/authority figures (beyond yourself) that may provide additional supporting information? I doubt there's a clear primary source that states "The storage condition is a bad idea due to x,y,z..." but doesn't hurt to ask.

Either way, thanks again for reaching out!

I fully understand the need for an “official “ quotable statement of your position, and I’m sorry that I cannot provide one.

However, after 35 yrs in mass spectrometry I can assure you that nobody in mass spec EVER advocated venting the instrument on a Friday afternoon just to save $2 of gas and electricity.

The ONLY time to turn off the pumps and vent the instrument is for maintenance.

So, shut down and vent the instrument, move to the new location and power up to enable pump down in as short order as possible!

Regards.
JMB

First, let me point out that rather than you, the receiving lab should worry about the storage conditions!

Then, in addition to primary vendors like Thermo, you may ask companies which sell second-hand instruments (e.g. MS Vision) how they store them because it sometimes takes a while before they find a customer and I doubt they have them switched on during all that time.

Finally, if I were them, if possible I would pump it down as soon as it arrives in my lab, as suggested by JMB, even if it is not used immediately.

To protect your own position, document that the instrument was working immediately before you shut it down.
You are quite right; after 6 months' storage in a damp environment not under vacuum there is a strong likelihood of it being difficult to get it back into proper working condition. At the very least it's going to need an enormous bake-out before risking letting it turn on any voltages.

If I were receiving the instrument and wanted to keep it in working order without being able to install it properly in the first instance, I would probably attach a foreline pump and keep it under vacuum, and if I can't make sure it's got the right gases, I'd block the ion transfer capillary to minimise air leakage into the system and reduce the load on the vacuum pump. That way you probably don't even need a big vacuum pump, just something to keep it safe and dry inside.

Caveat: this is all a guess; I'm not a repair technician.