Calculating SRBR for .csv spectra

Hi Agilent Community,


I ran a factorial design to find optimal instrument (MP-AES) parameters for analyzing my samples and I would like to know what specific procedure/function is used to determine signal-to-root-background ratio when using the 'Optimize' function in MP Expert to determine optimal viewing position and nebulizer flow rate. 

 

I ask this as I had to run my samples as a normal run and collect the raw spectra as some of my chosen parameters included pump speed (which can only be varied for a specific run and not during optimization) and read time (which would have been using the 'Optimize' feature a little time-consuming as I have restricted lab access during the pandemic.


I understand that there are a few methods that can be used to determine SRBR however I would like to keep the values I determine consistent with what the MP-AES would output. 

 

Thank you!

 

Shane Grant

  • I'm not sure this is what you need but here is some information from the MP HELP:

    “The optimum viewing position is derived automatically by maximum signal-to-root-background ratio (SRBR). The reason for this choice is that the ultimate optimization criterion is the ratio of the net signal to the background noise. The background noise depends on the level of the background light intensity. If the background light intensity is very low, as is often the case in the low UV, then the background noise is dominated by readout noise and is effectively constant. The best signal-to-background-noise ratio is obtained by maximizing the intensity of the signal. If the background light intensity is high, the background noise is dominated by plasma flicker noise, which is proportional to the background intensity. In this case the best signal-to-background-noise ratio is obtained by maximizing the signal-to-background ratio. At intermediate background light intensities the background noise is dominated by photon noise, which is proportional to the square root of the background intensity. The best signal-to-background-noise ratio is then obtained by maximizing the signal-to-root-background ratio.”

     

    Perhaps if you tell me a little more about what you are trying to achieve and what kind of samples you are running, I can respond in more detail.

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