Performance Report Parameters

Question

I have some questions regarding the performance report parameters for a 7900 ICP-MS.

What exactly is the background measuring? How is the "background" or noise of masses 7, 89, and 205 determined? At what point should an analyst be concerned due to the rising background?

I want to monitor the voltages of the pulse and analog detectors to gauge when replacement is necessary. I'm guessing I should use the parameters "analog HV" and "pulse HV" under Hardware Settings EM. There are also "Analog HV" and "EM HV Gain" parameters under Meter, however. The latter two are expressed as negative voltages. Can anyone explain the difference between these parameters, and which ones are more relevant for assessing detector condition?

Thanks!

Admin · Accepted Answer

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edgarvs · Answer

The background in the PerformanceReport is the noise level measured in the analytical vacuum room. It's measured by deflecting all masses by the Quad and measures only the pollution of the particles/elements in the vacuum chamber and electronic noise level. it's for a single Quad typical lower than 10 cps for a new system and rises up to 20-30 for a old and heavy used system. if the background is above 30-50 cps then please contact Agilent for advice.

It's not really needed to monitor the pulse and analog HV were the MassHunter software give a message when the detector should be replaced. This message is at a HV level that give the possibility to order the new ElectroMultiplier and wait for some time before the level is at max 2000V for pulse and 3500V for analog.