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A quick method for Detector Voltage calibration

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Ofir

Master

Posts: 75

Joined: Thu Nov 07, 2013 12:46 pm

Location: US, CA

Post Thu Mar 06, 2014 7:24 am

A quick method for Detector Voltage calibration

*** See important warning in red below ***
Occasionally we need to re-calibrate Detector Voltage. This is required when Tb159 Max Intensity / Pulse Count ratio (called Detector Gain) is <3 or >5.
The current manual instructions are to use the DAC Channel Setup tab in the Instrument Setup window and walk through select values of Detector Voltage.
It occurred to me that we have a ramp-up module that can be used for this purpose. The procedure I use is listed below.

    1. Start by running tuning solution through the syringe pump (of course).
    2. Open the Data Acquisition Settings window. In the Parameter area enter the following settings:
      a. For Parameter choose Detector Voltage.
      b. For Start Value type in the low end of the range you want to test (e.g., -2800).
      c. For End Value type in the high end of the range you want to test (e.g., -2200).
      d. For Step Value type in 5 (or 10 if you want to cover a larger range quicker).
      e. For Settling Time type in 2000.
      f. Leave Pushes / Reading at 76800.
      g. Leave Dual Count Start Point at 0.1.
    3. Open the Masses Per Reading window.
      a. Set to Pulse Count.
      b. Set max Y value to 300,000 (or less according to your instrument's performance).
      c. Select Mass: All or Tb.
    4. Open the ToF Range Per Reading (Mass Peak) window.
      a. Select Mass: Tb
      b. Set max Y value to 1,000,000.
      c. Check the Show History box.
Hit Run Acquisition to start the data collection. In the ToF Range Per Reading window you will see the Tb curves overlaying in real time. They should go from low- to high-peaked.
When the read is done, in the ToF Range Per Reading window hover over the peak of choice (say the 3rd curve from the bottom) to get the Tb Max Intensity, then hover over that same step in the Masses Per Reading window to get the Pulse Count. Calculate the ratio.
The image below shows what my screen looks like when preforming Detector Voltage calibration.

Image
Here is another image of this method run after CyTOF cleaning and XY realignment.

Image

Warning: Do not place high values (let alone zero) in the End Value field. You WILL fry your detector!

If you have been around in previous software (and user manual) version you may remember the Ir191 process, that used Detector Voltage ramp up and slope calculations. The initial steps described here are not dissimilar.

I hope you find this method useful, and would be very interested in hearing back from other CyTOFers on how well this works and if any problems come up.
Attachments
Detector voltage ramp-up calibration 020614.JPG
CyTOF Detector Voltage calibration Ofir
Detector voltage ramp-up calibration2.jpg
Detector Voltage calibration
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mleipold

Guru

Posts: 5796

Joined: Fri Nov 01, 2013 5:30 pm

Location: Stanford HIMC, CA, USA

Post Thu Mar 06, 2014 4:01 pm

Re: A quick method for Detector Voltage calibration

Hi Ofir,

What version of the CyTOFv1 software are you currently using?

I know the HIMC is (deliberately) a few versions behind. I'm asking because the Data Acquisition Settings window you show at the right of the first picture looks like it's in Service Mode rather than User Mode, since the Manual PDA1000 section is showing.

It's not clear from your instructions whether that section is used, but if it *is* in Service Mode, that would limit the applicability of this: I do *not* give my users Service Mode access....too easy to screw things up.


Mike
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robs

Contributor

Posts: 40

Joined: Mon Dec 02, 2013 3:42 pm

Location: University of Connecticut

Post Fri Mar 07, 2014 3:15 pm

Re: A quick method for Detector Voltage calibration

Ofir, in that software version could you dump to file and then open the data in excel and have it calculate the ratio for you automatically? I believe the file should include both the pulse and intensity values for each step.
Thats what I usually do for the MUG ramps since I have trouble getting accurate values from those mass plots sometimes.
Rob
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Ofir

Master

Posts: 75

Joined: Thu Nov 07, 2013 12:46 pm

Location: US, CA

Post Sun Mar 09, 2014 7:00 am

Re: A quick method for Detector Voltage calibration

Mike - we use version 5.1.648 and are quite pleased with it.
Yes, the first screen cap is from a test I did with the supervision of a DVS scientist (to make sure I don't break anything). However this method works in User Mode as well.
We operate our CyTOF software in User Mode always. Only DVS get to use God mode :-)
The second screen cap was taken in User Mode.

Rob - You are definitely right. I did dump the data and worked up some Excel magic to find the voltage sweet spot (pardon the Flow parlance). However I find that it's quicker to just use a calculator.
That being said, if someone is inclined to post a macro that uses the dump data to automatically provide the best (lowest?) detector voltage that would be sweet! - Hint hint... :roll: Maybe even trow in an interpolation for the absolute best granular value.
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robs

Contributor

Posts: 40

Joined: Mon Dec 02, 2013 3:42 pm

Location: University of Connecticut

Post Mon Mar 10, 2014 2:32 pm

Re: A quick method for Detector Voltage calibration

If/when I learn how to do that, I definitely will! haha
It would speed up a lot of those manual tuning procedures, and the metal quantification protocol, now I have no excuse not to learn!

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