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Issue with relatively similar CPS from 7800

nforrest

I have inherited a 7800 from a new job, when I run the standard method for the technique all of the counts come out relatively similar. Running a blank and then a calibration standard returns the same results, approximately. The instrument has been cleaned from the lens all the way back to replacing the sampling probe in the last couple of days. However, I still get relatively the same number for CPS of every element. I attempted to check each of our solutions via the signal monitor, only paying attention to Li. When I run the blank it returns a count of ~150 for Li and when I run the standard I get ~250-300 for Li, using the signal monitor. Along with cleaning everything, I also switched out all the standards for ones ran on a 7850 that came back fine on that instrument. I replaced the ISIS 3 the other day because it wasn't drawing up correctly and I just noticed that an error: 2607 Warning Y-axis movement disabled due to a partially closed top cover today. I am trying to figure out why this instrument returns the same values for all elements. They have not run this instrument for a couple of months and last batch I see, seems to have worked fine. Any suggestions or ideas would be helpful, I appreciate it.

  • 0

    Looks to me to be severely out-of-tune. If your probe ,nebulizer or cones are not blocked I would do a manual tune whereby I try each lens setting to see if the signal improves.

    With my tune solution (10 ppb Li, Y, Co, Ce, Tl) I notice that the Li signal decreases if the 10 ppb solution is old. I suggest you try to improve the Co (mz59) signal with a manual tune.

    Does your probe reach far enough into the tune solution?

  • 0

    Have you run the full startup tasks (torch axis, EM, resolution, standard lens tune, performance report etc)? Does it proceed without error and does it compare to those run prior if you do have history? For the performance report using a 1ppb tune solution (run through the carrier line to test) you should get >3000 for Li, 10000 for Y and 6000 for Tl. I would start there. If it is very poor you have a place to work from with troubleshooting. If it is good then I suspect the batch tune parameters need optimizing. Also if the instrument has been sitting without use I suspect the cell gases need purging for any He/H2 work. 

  • 0

    What are the detector voltages?  Select the Hardware button, or Hardware/Dashboard from Task manager, and click the Detector image.  Select EM setting.  What are the voltages for Discriminator, Analog HV, and Pulse HV?

    Was the instrument off, for an extended period?  Or was the vacuum left on for the months of inactivity?  As Chelsea suggested, will it make it through the startup routine?  With those counts, it will probably stop during the torch axis for low sensitivity.  If it fails at Torch Axis, open a new batch from Preset Method 200.8 (low matrix, no ORS).  Go to the Tune or Tune Modes Tab depending on software version. Click Configure Tune Way and select Signal Monitor, check the box for Show Hardware settings, and click OK.  Just above the top right of the graph area select the resolution/axis tab.  You should now see 3 windows.  Make sure your 1 ppb Agilent Tune Solution is up to the nebulizer and Start Signal Monitor.  Do you see peaks in any of the windows?  If so, with the low counts you are seeing, they are probably not centered. 

    If no peaks in the 3 windows, you will want to contact Agilent for service. 

    If you do see peaks in all three windows that are off to the side, then Run Resolution Axis and it should get your signal back.  To do this, Click the Hardware button, or in Task Manager select Hardware/Dashboard.  Select the Quadrupole image and pick Resolution Axis setting.  And run this.  If peaks do center, run the Startup routine all the way through. 

    If you only see a peak in Li7 (left most window) let me know.  There is a way we can try to walk the others back in.

  • 0 in reply to Chelsea Tajc

    I have run the full startup, it does not give errors and unfortunately the record keeping of past performance reports is few and far between. I found one from January of this year to compare to and at least check what everything was set at with that report. The instrument has been sitting for awhile and I noticed this morning that the He was out. I changed out the cylinder and am currently purging the line.

  • 0 in reply to carwogill

    Lens, cones, bridge, nebulizer, rotor stator, lines, have all been cleaned. It might be an old tune solution but it is the low sensitivity that is giving me problems. After I flush the He line, I will try to get better CPS with a manual tune. I was able to get a higher count when I checked the signal monitor with gas on for He, I was getting about 3000 counts for Li but then switching back to no gas reduced the counts to about 600.

  • 0 in reply to Tom Herzog

    The discriminator is at 4.3 mV, Analog is 2206 V and the Pulse HV is 1364 V. 

    The instrument was off but still had the rough pump running and an empty He cylinder for a while. I am purging the He line and will try again after that.

    This instrument is running MassHunter 4.5 and I can see peaks in the windows and only the far right looks like it is outside of range, it seems to be centered on a peak to the left of the large one.

    After the He purge, I will try some of the suggestions to hopefully resolve our issue.

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