r/massspectrometry

As title. I am in a situation where I have to choose one of these two for procurement without option of trail runs. Hence I need expert opinion.

What would be better got global untargeted metabolomics (Ultimate 3000 + Exploris 120 setup)?

I am a metabolomics noob. Please guide me. Both are 100 Angstrom.

I would be using it to do C13 tracer based work on mmmalian cells (after I gain expertise in basics, of course)

I also have option for ZIC-pHILIC (5 micron) 100mm x 4.6 mm

So my options are

ZIC-pHILIC (5 micron) 100mm x 4.6 mm

ZIC-pHILIC (5 micron) 50mm x 2.1 mm

ZIC-HILIC (3.5 micron) 100mm x 2.1 mm

Hi everyone

My current lab wants to acquire an LC-MS/MS spectrometer, and I've been chosen to learn everything about it and implement the methodologies. The problem is that no one in the lab knows anything about mass spectrometry and I was the only one selected to learn. As you can imagine, I'm quite lost, and I'd like to know where I can find information to study or familiarize myself with this equipment, as it's very expensive, and I don't want to end up breaking something or wasting money.

Thanks in advance

Hi so I deleted the CD channel in processing mode in chromeleon. Anyway how to get this back?

This is happening after the smart card stopped working and is replaced with a used one. The vacuum couldn't reach the same as before even after long time pumping. Now the vacuum achieved with the cover off is close to what the system can achieve before with cover in place, but the vacuum will worsen if the cover is put back on and slowly climbing. I have put the cover back on long enough time to see if it eventually fail the criteria for getting the instrument ready. I understand there might be offgassing from the chamber under the trapped heat when the cover is closed, but that should be the same as before the replacement. I am wondering if there is some kind of control mechanism that is still not working properly due to the smart card replacement. Anyone have any thought on this? Thank you.

Hi there,

I am specialized in the small molecule world, and have never touched anything large molecule. Now, my manager wants us to start analyzing large molecules, from peptides, polysaccharides, to complex polymers. We are a small lab and only have HPLCs, a single quad GC-MS, and a HRMS (Waters Xevo G2-XS). My question is the qTOF. We still use this for small molecule needs (mainly impurity screening and residue analysis). I know that Xevo can be used for both small molecule and large molecule analyses but I thought that it is generally dedicated to one way, not both. Is there anyone who uses single instrument for both small and large molecule applications and switch them frequently?

I am specifically asking if anyone does this on a Waters HRMS. Years ago, when I had a training on a Synapt, the trainer told me that she would not recommend to use Synapt for both applications because the Waters calibration solution mix for large molecule has a component (I don’t recall exactly but somewhere below m/z 200) that sticks to the instrument and could cause a calibration issue when switching back to the small molecule application. I wonder if that’s true. I would love to hear your experience on a Xevo qTOF. Thanks!

Hi everyone! I’m troubleshooting a Waters Xevo G3 QToF and I’m having an issue that is preventing us from calibrating the instrument.

We are trying to calibrate with our usual calibrant, but there is a very strong background peak already present even before we introduce the calibrant. The background signal is strong enough that the calibrant peaks are overwhelmed/interfered with, so we cannot get a proper calibration.

The situation is:

• LC flow is OFF
• Sample infusion is OFF
• LockSpray infusion is OFF
• Both Sample Flow Control and LockSpray Flow Control show “Idle”
• Sprayer position = Sample
• However, we can still see what appears to be a continuous spray from the sample sprayer
• There is a strong signal on the QToF even though we have not infused calibrant or sample
• The major unexpected signal appears around m/z 60
• The signal is strong enough that when we try to introduce the calibrant, the background peak overwhelms the calibrant signal and we cannot calibrate properly

Current Fluidics settings are:

Sample Flow Control

• Infusion flow rate: 5.0 µL/min
• Flow state: Infusion
• Reservoir: C
• Status: Idle

LockSpray Flow Control

• Infusion flow rate: 10.0 µL/min
• Flow state: Infusion
• Reservoir: B
• Status: Idle

Sprayer position: Sample

I understand that the displayed “Flow State: Infusion” does not necessarily mean the pump is actively running because the actual status is Idle.

What is confusing us is that we appear to have continuous spray/background signal despite both fluidics being Idle.

Our main concern is that this is preventing calibration. We don't want to start replacing valves, tubing, or other consumables without knowing what is actually causing the problem.

Has anyone experienced this on a Xevo G3 QToF?

Could this be caused by:

• A fluidics valve not switching completely?
• IPA/wash solvent leaking or being routed to the sample sprayer?
• Residual pressure/solvent in the fluidics line?
• A divert-valve or fluidics routing issue?
• A problem with the sample fluidics pump/valve?
• Or could the strong m/z ~60 signal be coming from another source entirely?

What would you check first, and is there a way to completely stop/isolate the sample fluidics so we can determine where this signal is coming from?

I’ve attached a screenshot of our current Fluidics/Tune page. Any advice from anyone familiar with the G3 would be greatly appreciated.

https://preview.redd.it/q0mqd9x60zih1.png?width=1132&format=png&auto=webp&s=b6720caa743614890b9edf541d9ccf02c97d719f

Do you really need a helium leak detector when changing a helium cylinder for GC-MS?

We normally check the regulator and fittings after a cylinder change, but I’m wondering if buying a dedicated helium leak detector is actually necessary for routine use.

Do most GC-MS labs use one?

So as the title said… I left my gcms oven baking overnight at 325 and forgot to turn it back at 55. I usually do baking when there is high air/water or column is newly changed but I did it bc of the air/water leaks.

I did search online and says it is safe as long as it is under or at the limit of manufacturer but i also saw that phenomenex only recommend 1-2hrs when you bake.

Based on your experience (if you encountered this), does it affect my gcms? Should i clean the ion source again and change filaments just in case it was busted?

Thanks

Hey team, recently involved in development of simultaneous estimation of Indacaterol and Glycopyrronium

Any suggestions for mobile phase ??

Isocratic

In laboratory applications, maintaining a stable temperature throughout the bath can be just as important as reaching the target temperature.

For those using circulating water baths:

• How do you verify temperature uniformity?
• Have you experienced temperature differences within the bath?
• Does circulation significantly improve your results compared with a standard water bath?
• What temperature range do you typically work with?

Would be interested to hear experiences from lab and QC professionals.