Cleaning protocols - new CyTOF "owner"

[jimbomahoney]

Hi all,

I'm the technician assigned to operate and maintain the CyTOF (Helios) in our facility.

Fluidigm have just trained me on the machine and I'm about to do my first clean of the glass / cones.

They recommend 10% Citranox (acid) for the cones and 10% Contrad100/Decon90 (base) for the glass.

I can order Decon 90 easily and it's cheap, but I can't source the Citranox on the ordering system we use, plus it seems expensive from what I can see. Am I right in thinking I can use 3% Nitric acid instead? Does it need to be a certain grade? EDIT - Found some Citranox at a decent price.

Thanks for any advice for a Helios cleaning newbie!

[mleipold]

Hi James,

You have to be careful about using nitric with the cones: I think they're made of stainless, and the nitric will eat the nickel out if you're not careful. I know of a lab years ago which had to replace a skimmer-reducer (smaller cone; the really expensive one) after someone accidentally left it in 3% nitric overnight.

If you do use it, use it briefly, no more than 5-10min or so, then rinse with plenty of water.


Honestly, we use citranox for the cleaning of the glassware when needed. I think we source it from Sigma-Aldrich.

For the cones, there's also the Brasso cleaning method discussed here: viewtopic.php?f=7&t=1066&p=3178&hilit=brasso#p3178 I don't know if it's Fluidigm-approved, but a lot of people use it.


I would also recommend getting some long pipe-cleaners/fuzzy craft straws to scrub out the injector. Cotton swabs (Q-tips, "cotton-tipped applicators", etc) are also good for scrubbing lightly at the cones before or after any of the cleaning methods.


I don't know if Fluidigm mentioned it, but some super fine-grit sandpaper is often useful for occasionally scrubbing the igniter pin, and a green kitchen scrubby pad (the ones that look like a pad of steel wool, but are some kind of plastic) is good for occasionally scrubbing the Rf coil. In both cases, make sure that you wipe them off thoroughly with methanol on a Kimwipe afterward.......keep wiping until the Kimwipe comes back clean.


Mike

[jimbomahoney]

Thanks Mike - the brasso method sounds like a winner.

Little & often makes sense, rather than infrequent and strong (e.g. sonication / acid).

[desireeBCRT]

Hi James,

we use dental brushes (the very thin ones) to clean the end of the injector.

Desiree

[jimbomahoney]

That's a genius idea, thanks!

[anitamkant]

Hello James,
Welcome to the community of CyTOF users/operators.
Helios User guide provides detailed description of all the parts and the cleaning procedure. It can be downloaded from:
https://www.fluidigm.com/binaries/conte ... igm%3Afile

Please do contact Fluidigm’s technical support team at techsupport.fluidigm.com for any further technical questions and availability of Citranox from a local vendor.
Please do keep in mind that use of nitric acid can cause accelerated wear of the Sampler and skimmer-reducer cones that are made of nickel.

All the Best!
Team Fluidigm

[jimbomahoney]

Other than leaving the cones in Citranox for too long, has anyone damaged them in some way?

If so, how and what were the symptoms?

I think I'm cool with the glass components, but paranoid about the cones!

[mleipold]

Hi James,

Just to clarify: citranox isn't the issue with the cones, it's any use of *nitric*......don't do more than a few minutes, if you do it at all.


The easiest way to damage the cones is to hit the tips against something and damage (break or warp) the orifice. In general, this manifests as increased CV.

Alternatively, the skimmer and reducer shouldn't wiggle: if they do, tighten the two screws on the back. If they can wiggle or there's some other issue around electrical contact, I've seen the Current value go up significantly, or be unstable: you can imagine that if you have a bad connection, your Current value will be changing. This would manifest as changes in signal intensity, as the ions aren't being guided into the orifice with constant efficiency.


Mike

[jimbomahoney]

Thanks Mike.

Makes sense.

[jimbomahoney]

Am I right in thinking that it's only the skimmer/reducer cone that has current flowing through it and is therefore the "current" value in the QC results?

I'm assuming this because it makes physical metal contact, rather than being held in by the o-ring like the sampler cone. Although I guess the sampler cone makes contact with the metal behind it...