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Tuning fail for %RSD parameter

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Chikara

Participant

Posts: 6

Joined: Mon Nov 03, 2014 11:20 pm

Location: South San Francisco

Post Tue May 03, 2016 6:00 pm

Tuning fail for %RSD parameter

Hello,

Has anyone dealt with failing the % RSD parameters during tuning? I'm trying to tune the instrument today and have failed 3 times.

All the isotope channels Cs, Tm, La, Tb, Ir are >3.1% and that seems to be throwing the flag. Any suggestions would be appreciated.

The instrument is a Helios upgrade from a CyTOF 2 and I cleaned the instrument yesterday.

Thanks,
Chik
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Tue May 03, 2016 6:28 pm

Re: Tuning fail for %RSD parameter

HI Chik,

A few questions:

1. When you said that you cleaned it yesterday, did you also tune it yesterday (ie, the issue is brand new today, and the machine *had* worked post-clean)?

2. How do the rest of your parameters (DV, NG, MG, Current, Tb and Tm Duals, etc) look compared to your last successful tuning?


Mike
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Chikara

Participant

Posts: 6

Joined: Mon Nov 03, 2014 11:20 pm

Location: South San Francisco

Post Tue May 03, 2016 6:54 pm

Re: Tuning fail for %RSD parameter

Hi Mike,

I did not tune yesterday, so this is the 1st tuning attempt post-clean procedure yesterday.

The other parameters; DV is about -1650 not any different from recent voltages, NG is 0.29 and MG is 0.30 on today's failed runs.
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Chikara

Participant

Posts: 6

Joined: Mon Nov 03, 2014 11:20 pm

Location: South San Francisco

Post Tue May 03, 2016 7:22 pm

Re: Tuning fail for %RSD parameter

Update:

Got off the phone with Leslie F. from Fluidigm and she gave me some good info that resolved the issue. The high % RSD is an indication that there is a flow issue, be it the nebulizer, clog, etc. I knew I didn`t have a clog but according to Leslie, my Neb gas value of 0.29 was way too high and it`s an indicator of a failing nebulizer. She had me change nebulizers and reset the neb gas value in the control panel to 0.15, check that the automate range box was checked under the tuning manager gases & current tab, click on show range and make sure that the values were 0.14 and 0.17 for start and end, respectively.

I performed the tune again and everything passed.

...onto acquiring real samples...
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Tue May 03, 2016 8:23 pm

Re: Tuning fail for %RSD parameter

Hi Chik,

I'm glad it was something as simple as that. It makes sense that %RSD is a nebulizer issue. I would expect, though, that your Tb Dual and Tm Dual would also have markedly changed from previous Tuning, though: it's been our experience that if a nebulizer is partially clogged or something, the Tb and Tm Dual go down b/c half your sample is winding up on the Spray Chamber walls.

Before you throw out the nebulizer, you might try checking the seal on the NG tubing. We haven't had a huge change in NG, but we have had that little O-ring on the NG screw start to slip. And when we've had seal problems on the Spray Chamber (missing O-ring, mis-aligned O-ring, or just not screwed together all the way), the MG value jumps noticeably from the previous Tuning.


I would also recommend re-tuning the machine *immediately* after a clean: that way, you remember what you did clean (and what you moved during the clean), and so it's easier to troubleshoot than if you're trying to remember even one day later.


Mike
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Chikara

Participant

Posts: 6

Joined: Mon Nov 03, 2014 11:20 pm

Location: South San Francisco

Post Tue May 03, 2016 8:44 pm

Re: Tuning fail for %RSD parameter

Good suggestions Mike, thank you. Although I always feel like doing a tune after my cleanings would cause uuneeded wear & tear on my detector if the instrument isn`t going to be run for real samples that day.

The Tb and Tm Duals were not down during the failed tunes, above 1.7 mill for Tb and above 1.8 for Tm. These values were consistent with previous tunings.

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