[ICPMS 8900] custom tune for best sensitivity of UO2

I am using 8900 for measuring 236U with a reaction gas of oxygen (25%). The high sensitivity for U is extremely important. With autotune using provided tune solution (59Ni, 89Y, 205Tl) the sensitivity for U is often in the range of 3 x10(5) cps/ppb. The sensitivity is about one order of magnitude lower in reference with pubished scientific reports. The reports say before the measurement, the instrument is tuned with U standard solution (1 ppb) for the best sensitivity. Could you please teach me how to do the custom tune aiming at U measurment? Any advice for accurate measurment of 236U/235U is also helpfull for me (for example: intensity ratio correction, dead time correction etc.). 

  • Right click your tune screen in the batch and select Parameters for Autotune. From there you can change the desired masses that the autotune will use to reflect the 1ppb U solution. 

    Dead time correction is performed from the Hardware Dashboard. You may need to turn on this feature in settings (in the options section) You can run the correction using the Dual Mode 1 and 2 solutions which are 1ppm and 50ppb Erbium. You should have received these with your instrument (it's ok if they are expired), or you can remake them. You can also use In. 

    For mass bias correction you will need a reference material with a known ratio for U isotopes. You will run this solution using the IsoStd Sample Type. Make sure Isotope Ratio is turned on in Setup then enter the known abundancies from the reference material (just type over the theoretical ones). If you haven't already, I recommend reading the help section on setting up Isotope Ratio Analysis. 

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