CyTOForum

Hi everyone
I've got a problem on the Helios with some heavy metal streaks, Au, Hg & Pb

machine has been fine for months, very little problems at all.
after running normally on friday, I cleaned the cones and glassware on Monday. citranox and contrad respectively, & rinsed with MilliQ water
today, everything started up ok, but I getting some massive streaks in those high metals (hope you can see a pic of the screen)
everything else looks normal.
Wash solution hasn't touched it.

I've tried a fresh (new) injector & several nebulzers & nothing has shifted it.

I've also tried a small ROI on my IMC, looking at the same mass range to see if its contamination in the gas, but didn't see anything like that.

Anyone come across this before or got any good ideas?
thanks
Richard

Hi Richard

Lead and such is usually from water-did anything change about your MilliQ system? Alternatively, if tap water was used to rinse the cones, and they weren't adequately rinsed with MilliQ (or allowed to dry completely, or stored in a damp container), it could be coming from the them. You may want to swap out the cones if you can, or just re-clean and rinse them extra well. I usually sonicate 15' in dilute Citranox solution, 15' in MilliQ water, then rinse thoroughly under running DI water, then MilliQ, and finish off with a rinse in MeOH and dry in a fume hood. The MeOH step seems to do a good job of getting any oily residue off, and has the added feature of helping your cones dry faster

It is strange you don't see the same problem on IMC, but I am less knowledgeable about that system. As usual, a good 10-20' of 2% nitric acid through the fluidics can't hurt, nor can a backflush of your PSI, in case you've got debris is the flow rate sensor.

Best of luck!

Hi Richard,

There are a few odd things.

1. Gold is a really really rare contaminant, unless you've been running gold as a probe. For example, I used Au-lectins in some work I did in Toronto years ago.

Is there any chance that this came from a patient sample? For example, gold is sometimes used in RA treatment.

2. I'm really puzzled by the fact that you're not seeing all the natural abundance isotopes expected. For example, you see a ton of 199Hg and 202Hg, but essentially zero 200Hg, which is even more naturally abundant than 199Hg. Even if your Hg contamination came from a source with a weird distribution, you'd still expect to see *something*.


I'd try running Tuning Solution for 30min and see whether that makes a difference. It's 2% nitric, which should at least help strip the Hg and Pb, and the metal ions in Tuning can also help strip things out since they'll compete for the same nonspecific metal binding sites in the tubing, etc.

Hopefully that will take care of things..... aqua regia to strip out gold isn't something that you want to do unless you absolutely have to (and would need to be discussed with Fluidigm, as it's nasty stuff).

Mike

update

I have no idea what it was, I don't think it was metal in there.
Running without any fluid going in still gave the heavy streaks, so I didn't think it was coming from the sample line


I powered off the entire instrument & restarted.

All that high signal had disappeared.

Tuning looks normal now.

I'm happy its gone, but still wondering what it was. TOF physical issue or detector issue? no idea

Richard