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Periodic fluctuations in events/sec acquisition

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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Wed Dec 01, 2021 7:50 pm

Re: Periodic fluctuations in events/sec acquisition

Hi Greg,

When you took that image, was that using the old-style screw-on Helios nebulizer gas tubing (with the white part kept on the nebulizer itself), or the newer force-on nebulizer gas tubing (with no plastic on the nebulizer, just the white plastic part on the gas line)?


Mike
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Chowduck

Contributor

Posts: 29

Joined: Wed Nov 19, 2014 4:39 pm

Post Wed Dec 01, 2021 7:59 pm

Re: Periodic fluctuations in events/sec acquisition

Hi Mike,

That video was from 2013 with the old-style Helios nebulizer (white part on the neb). It was more to demonstrate how in general, air bubbles entering the sample line can cause pulsing.

Greg
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Wed Dec 01, 2021 8:02 pm

Re: Periodic fluctuations in events/sec acquisition

Hi Greg,

Thanks for clarifying.

I was asking more out of general interest: in our hands, different parts fatigue and need to be replaced in the two different Neb+Neb Gas configurations, even when they exhibit the same bad behavior.


Mike
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TomerWeizmann

Contributor

Posts: 43

Joined: Mon Apr 07, 2014 11:58 am

Location: Weizmann Institute of Science - Israel

Post Fri Dec 10, 2021 6:31 pm

Re: Periodic fluctuations in events/sec acquisition

Update:
The fault has been traced to defective (in manufacturing) nebulizers producing ‘bubbles’ (visible).
FDM supplied us with new validated ones.
Please see below how our runs look now.
Thank you everyone!
Tomer
Attachments
FDM_Markham_Cells_2nd_Batch_WIS.PNG
FDM_Markham_Cells_2nd_Batch_WIS.PNG (134.64 KiB) Viewed 4053 times
Dr. Tomer-Meir Salame
Head, Mass Cytometry Unit
Life Sciences Core Facilities
Weizmann Institute of Science
E-mail: tomer-meir.salame@weizmann.ac.il
https://www.weizmann.ac.il/LS_CoreFacil ... etry/about
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Fri Dec 10, 2021 6:40 pm

Re: Periodic fluctuations in events/sec acquisition

Hi Tomer,

I'm glad that you've solved the issue.....this sort of thing is maddening to chase down!

Do you know how the nebulizers were defective? Anything cracked, broken, too long, too short, etc that we could see under a microscope? In other words, is there anything that the rest of us should check as we replace nebulizers? And are you and Fluidigm going to follow up with Meinhard?

Did you go ahead and sonicate the grounding nut anyway? Or have you been waiting until after the verified nebulizers were tried?


Mike
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TomerWeizmann

Contributor

Posts: 43

Joined: Mon Apr 07, 2014 11:58 am

Location: Weizmann Institute of Science - Israel

Post Fri Dec 10, 2021 7:09 pm

Re: Periodic fluctuations in events/sec acquisition

Hi Mike,

1. According to FDM they were defective in manufacturing, resulting in microscopic cracks (from what we could see sometimes visible under the microscope), or a not good seal at the area where the inner capillary of the nebulizer is touching the outer part (on the back side). Thus, allowing gas to enter and produce bubbles, which are clearly visible with the naked eye.
2. From what we know, and confirmed by FDM, there are at least three different lengths of nebulizers tips, but these were tested and do not affect performance (personally I prefer the long ones).
3. Bottom line is to check your data vs time for a consistent flow, and look for bubbles (stop/go) in the exposed part of the nebulizer when running. If you observe fluctuations, and you rule out clogs, the above may be the cause.
4. FDM agreed to validate our nebulizers and capillaries prior to sending them to us – this is a satisfactory solution for us. I leave it to them to troubleshoot with Meinhard etc.
5. Yes. As you have recommended, we have also sonicated the grounding nut with the Citranox, MeOH, DIW solution – we still observed fluctuations. But it is a good SOP. Thanks.

Thank you for all the help!
Tomer
Dr. Tomer-Meir Salame
Head, Mass Cytometry Unit
Life Sciences Core Facilities
Weizmann Institute of Science
E-mail: tomer-meir.salame@weizmann.ac.il
https://www.weizmann.ac.il/LS_CoreFacil ... etry/about
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