usp signal to noise calculation

[chrisknutsen]

The current USP chapter on chromatography <621> says to calculate the s/n ratio by 2H/Hn, where H is the height of the analyte peak and Hn is the height of the noise. Can anyone tell me where the 2 comes from? I seem to remember that it is usually H/Hn

Thanks

[tom jupille]

That is a large, economy-size "can of worms". It centers around exactly how you measure the noise and from where you measure the "signal":

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