ICP-MS: Pulse-Analog Adjustment

To do this, the ICP-MS should already be running.

The detector uses two modes, pulse and analog. In pulse mode, voltage is applied to all electron multiplier stages, and each pulse is counted. In analog mode, part of the detector is turned off, and the signal is read by a sensitive analog current meter. P/A factor adjustment produces a series of factors that match pulse signals with analog (current) signals, so that both give the same, linear response over a wide range of signal intensities.

P/A factors are made using a solution that has element concentrations that span the boundary between pulse and analog switchover count rates, so about 10 ppb in solution, except a bit more for the lightest elements or small isotope abundances.


In the hardware panel, right-click on the detector icon and select the P/A Factor Setting


You can change the list of elements in this window, but it is generally easier to import them from a file where they have all been set up ahead of time to match a stock bottle with all the elements in it. Right-click on the white space and select Load Mass List from Method.


Navigate to the Data/Batch Template folder.


Select the file you want. PA_factor_aqueous_elements_list.b has a lot of elements in it.

If you want to make your own, open the file anyway, make the changes you want, and then save it.


Move the autosampler probe to the container with the P/A factor solution in it, and press the Run P/A Factor Auto Setting button. The P/A factors will be collected, and will be saved as the defaults unless overridden by P/A factor acquisition settings in Batch files.

Remember that you can do real-time P/A Factor Adjustment box during runs, by clicking the check box in your analysis method.