High background for mass 7, 89 and 205 on tune (no gas mode) ICP-MS 7700

lipo2a 1 month ago

Hello all,

I have an issue with the tune in the batch on ICP-MS 7700 in no gas mode.

When I launch a Start-Up, the Backgroung on mass 7, 89 and 205 is good but not in tune version (very high compared last time).

For example, the tune in the batch (in no gas mode) indicate :

Mass 7 : 12937CPS, %RSD 3,9, Background 18,8
Mass 89 : 65696CPS, %RSD 2,4, Background 10,9
Mass 205 : 33990CPS, %RSD 3,4, Background 21,1

Oxide ratio 156/140 : 0,923%
Doubly charged 70/140 : 1,256%

In the past, the value for these mass were below 5 in background.
When I launch the performance report in the start-up (no gas mode too), these values are good.

For information, the cones and glassware have been cleaned and new tubings were installed.

What is the problem with the high background in no gas mode ?

Thanks in advance for your return,

Have a good day !

0 ulrichntaniel 24 days ago

Hello,

Please perform a full spectrum using the tool available in startup. If you don't have full spectrum available. You need to create a batch, select all masses and post the graphic zoom after acquisition. The reason it's working in performance and not in tune could be also corrupted batch file. Try another batch to see if you have background also.

The integration time could be 0.1 for all of them. We are looking for a trend is the zone 200-260 amu.

Depending of the result you may need onsite service has it will required quad cleaning.
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0 cschulz 23 days ago

The Background values are so called "off mass background".

This could indicate an electronics or contamination problem of the quad.

In your case, the values are still quite ok.

I would guess, one of the lenses has a setting which is causing this.

Have you tried, creating a new batch (from scratch) and tune it?

Best Regards

chris
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