P/A Factor what it it is?

Hi, I am new to ICP-MS, can you please explain to me what P/A factor stands for?

  • Simply, We could have wide dynamic range by P/A factor in calibration curve.


    If it has only pulse mode, its calibration curve is saturated easily.


    A pulse range has low concentration(low intensity) and a Analog mode has high concentration(high intensity).


    P/A factor is bridge for Pulse and Analog through calculated factor values.



    So, In Data analysis program you could check what range(not attached picture).


    In DA calibration curve,


    Blue point is pulse range.

    Pink point is P/A factor range.

    Green point is analog range.

  • A dedicated solution is required to readjust the P/A factor.


    PA factor tuning solution set – p/n 5188-6524
    • Multi-element custom mixes to provide suitable signal for detector cross- calibration 100 ml each:
    • P/A Tuning-1 (in 2-5% HNO3) 20 ppm Zn, Be, Cd, As
    10 ppm Ni, Pb, Mg
    5 ppm Tl, Na, Al, U, Cu, Th, Ba, Co, Sr, V, Cr, Mn, Li(6), Sc, In, Lu, Bi
    2.5 ppm Y, Yb
    • P/A Tuning-2 (in 10% HCl and 1% HNO3 with trace HF)
    10 ppm Mo, Sb, Sn, Ge, Ru, Pd
    5 ppm Ti, Ir

  • Hi. Do I need to calibrate P/A factor if the nebulizer is changed from 50ul to 20ul? 

  • Hi


    No need to change in this case. Only need to change after a time period, depend on the load to the detector. if there was a big load, read high count rate. And the pulse or analog voltage is changed due to degradation of the detector then a new p/a factor should be applied. 


    However, the p/a factor option in the batch (in the MassHunter 4.1 and higher versions) is a quick and easy way to adjust the p/a without notice. So, if you check this option by default then you have never pay attention to it anymore.



  • Hi ,

    Thank you for a fast response.


    We are using ICP7700. The nebulizer is changed from 50uL to 20uL due to part unavailability. Since then the CPS became unstable. Low sensitivity issues came up. QC is unstable. The P/A factor tuned for 50uL originally. So, I just think that P/A factor tuning with this new nebulizer would actually help. What's your suggestion?

    The amount of sample/second introduced to the machine is reduced more than half. I assume that the pulse reduced too. This might affected the P/A factor.


    Please help. 


  • If the pulse or analog voltage isn't changed no need to adjust the p/a. The detector isn't related to the sample intro. so changed to the sample intro doesn't influent the working of the detector p/a factor.

    However, a re-adjustment of the p/a factor, if you doubt about the trueness, could always be run if the sensitivity of the p/a tune solution is ok.