Noise Threshold calculation in Agilent Chem Station software

[KarenJ]

Hi,

Recently while doing some method validation exercises I printed out the peak purity page from the Chem Station Data Analysis software. On this page there is a value called Noise Threshold. I believe that this value can be used to calculate the method detection limit but I'm not really sure how it is derived or the correct way to use it. Is it intended to be an estimate of the actual noise level? In this case I would multiply it by 3 to get a detection limit estimate (signal:noise = 3 at detection limit). I'd like to know where it comes from rather than just blindly use it. The manual doesn't help.

Thanks,

Karen

[ntruong]

On this page there is a value called Noise Threshold. I believe that this value can be used to calculate the method detection limit

I believe this "noise threshold" is used for peak purity determination of the main compound, which is the same as the noise range (before and after peak of interest) you use in determining the signal to noise. I tweaked this value all the time when my peak purity failed or exceeded the threshold limit. I have never used it to estimate the LOD. For method validation, I make a very diluted solution until I get the signal to noise of 3, which I think would make QA and audit-inclined folks happy.
Good luck,