Hi,

It should definitely be possible to run native MS on a (recent) QToF mass spectrometer.

What protein would you like to see flying?

I think it is important to have sufficient (often more than you think) in source collision (it's called isCID in the Bruker MicrO-TOF II that I used to use to run native MS) to shake up (decluster/desolve) your large protein ions.

Could you share a summary of the settings you've been using so far?

Dear Eef Dirksen, thank you so much for your advice.

I worked with omalizumab monoclonal antibody sample.

Actually, it didn't take a much time to optimize a parameters but without a right direction set by you the work might be very troublesome.

Agilent QTOFs have a limited ISD parameters to set up. I tuned a Fragmentor Voltage, Gas Temp and Gas Flow to raise the sensitivity. But the only feature that allowed me to obtain a good resolution was a Collision Energy in the CID cell. To decluster the ions I lifted it to 48 V.

For the moment I tested both a standard ESI and DualJetStream courses. I found that even with optimized parameters the sensitivity of the AJS is approximately nine times lower than for the standard ESI. I attached the list of tuned parameters with ESI (final values) and a spectra (green before and red after tune) below:

Flow rate ~5uL/min (after flow splitter)

MS Abs. threshold 1

m/z range 400-9000

Scan Rate 1 Hz

Gas Temp 290C, Flow 17

Nebulizer 12 psig

Collision Energy 48

VCap 4500

Fragmentor 420

Thank you again for your assistance!

Hi Maksim

The 6550 has no fragmentor even though it is displayed in the software this is due to the ion funnel design therefore it is pointless optimising this voltage, i believe on the 6550 it is fixed at 380. The parameters i would optimise in order are:

1. Stick to the ESI source over the jet stream as the extra heat from the jet stream will not allow your compound to stay in the native state

2. Turn down the source heating and gas flows

3. The main voltages which will effect your compound are those in the ion funnel dependent on software version in the method under advanced parameters you need to turn down the funnel RF voltages my recommendation is HP funnel RF = 90, LP funnel RF = 80. If you cant see this in the method you may have an older version of Masshunter therefore change in the tune file and save the tune file

4. Dependent on the m/z of your compound it is also worth adjusting the quad AMU manually in the tune and saving

This should get you to a good start and as you have noticed other parameters such as VCap will have a big influence

Regards

Sufyan