Max LOQ bias calculation

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Max LOQ bias calculation Zac  2020-08-06
 

Is there any documentation on how the Max LOQ bias is determined, or can you it explain it briefly? Thanks

 
 
Nick Shulman responded:  2020-08-06
After Skyline has determined the calibration curve, Skyline then examines each of the concentration levels along the calibration curve.
For each concentration level, Skyline takes the mean of the observed peak areas of the external standards at that concentration level.
Skyline uses the calibration curve to calculate the concentration from that mean area.
The bias is the difference between the back calculated concentration and the actual concentration, all divided by the actual concentration.

Note that we recommend using Skyline-Daily if you want limit of quantification. The way that Skyline 20.1 determines limit of quantification is problematic, because Skyline starts looking at the lowest concentration point, and stops looking as soon as it finds a concentration level which satisfies the criteria. This is often the wrong thing to do, since higher concentrations might fail the criteria, but Skyline still reports a low LOQ.

In Skyline-Daily, Skyline starts looking from the highest concentration level, and stops when it finds a level which fails the criteria.
-- Nick
 
Zac responded:  2020-08-06
Thanks, this is very helpful. I will look at Skyline-Daily. Interesting to know how skyline goes about finding the LOQ, i wonder if having an upper limit of quant would be helpful-with upper limit searching from highest, and lower limit searching from lowest up