Agilent 8900 replicate instability in O2 mode

Hello Agilent community,

We have observed systematic drift between replicates within any given measurement of element counts in O2 mode. An example of this is shown in the figure below (showing five separate measurements of the same sample with five replicates performed during each measurement). We do not see this systematic drift in any other gas mode (see No gas figure also below from the same run). 

For this run the stabilization time for the O2 mode was set to 30 seconds. Tuning parameters for the cell are:

O2 gas flow: 20%

OctP Bias: -3 V

Axial Acceleration: 1 V

OctP RF: 180 V

Energy discrimination: -8 V

Any insight would be much appreciated.

Matt.

Parents Reply
  • Thank you, yes I see now. One thing I try when I have drift in one mode is to try and figure out if it's specific to that mode or specific to the timing of that mode.

    To easily rule out one problem, I will do a very quick calibration in just that tune mode. If the drift persists, I know it's an issue with that gas. If the problem is resolved then it's likely a timing issue and maybe I need longer stabilization for transition, I might need to adjust preemptive rinse time if I'm using it, etc. 

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