Sodium counts are increasing.  How to I manage/control this

Hello,

 

I am running a 7800 ICP MS for EPA 200.8 method.  I have noticed the pass number of months the sodium counts during my warm-up and shut down are running in the 50,000 to almost 100,000 counts.  After 30 mins to 2 hr  (warm-up or rinsing) the counts drop  very little. Also the last few  EPA tune report shows a large peak next to mass 24  (left side) in the Resolution/Axis section of the report which I'm assuming is mass 23 (Na).    We use ultra pure acids and water (18.2 Mohms).  I understand we can not get rid of Na completely. Are there any suggestion on how to control/decrease the Na counts?

 

I attached a copy of the EPA Tune Check report to show the large Na peak that runs on the left side of mass 24.

Thanks

  • Can you tell me which software version you have?

  • Do you do the resolution/axis at startup?

     

  • Software version 4.6.  An Agilent service agent downloaded using Subscribe net back in early March.  Jim, the other user of this instrument wrote the following information down in our instrument notebook: G7201-60527-20191212.iso from download Flexnetoperations.com during the time the new version was downloaded.

     

    Thanks,

    Jackie

  • Start- up:

     

    1.       Warm-up for 30 mins to 1hr  with the sample probe in 1% HNO3 and the Internal Standard line in Ultra-pure water,

     

    2.       Performance tune: 10ppb of Tune solution.  Resolution/Axis is performed during.

     

    3.       Tune Check using EPA 200.8 tune check solution, suing No Gas mode:  First the Autotune is run then follow by EPA 200.8.  Not sure why we run both since we generate the same report with different time stamps.  Plus can you explain to me why we can run a tune check in no gas mode but run a batch in He mode?  No one here in the lab seems to know.  I thought it makes more sense to run your method tune checks in the same mode as the one you use in your batch run.

    I’m attaching print-outs of the Performance tune and the two method tune checks (autotune and EPA 200.8 tune)  for your review.  Ever since the software was update from 4.5 to 4.6 we now get a printout of the Autotune  using the same EPA Tune check report format.  Before it would pop a message that stated “Semi Auto tune completed successfully “when auto tune finished.

      Thanks for your help,

    Jackie

    attachments.zip
  • Ok I think maybe it's time to do some maintenance.

     

    Please sonicate your cones in water, dry and put back in and then see how that works

     

  • OK, the Performance tune and two tune checks are from post maintenance.  I normally do pre and post maintenance on batch .

     

    Pre-run Maintenance (before a run):

     

    ·         replace all peri-pump tubing.,

     

    ·         rinse/soak Spray chamber and connector tube in 5% HNO3 for 3-5mins, rinse with lots of water and air dry or switch to clean ones,

     

    ·         sonicate cones in ultra-pure water for 5 mins and dry with Argon gas.  (note: current cone has only been used once in September.  They were conditioned with Ca solution prior to use)

     

    ·         Run 1% HNO3 through sample probe and ISTD lines and monitor for Na, ISTDs, Sb, Mo and other few elements and try to drop down the counts to less than 1000.  However, Na and Sc always >1000 counts

    Post run maintenance:

     

    ·         Run 1% HNO3 for 30 mins to 1hr, until I start seeing the counts drop below 1000 counts (Na & Sc do not drop very much.

     

    ·         Run ultra-pure water for 30mins and then turn off the plasma.

     

     

    I’ll go ahead and sonicate again but will not be able to run until Saturday.  My work schedule is Sat to Wednesday. I will send you an update over the weekend for you to view Monday morning.

     

    Thanks,

    Jackie

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