How is the S/N ratio calculated?

Ph. Eur. users are advised to continue calculating the S/N ratio on a window “at least 5 x Wh”, instead of “20 x Wh” (published in the 11th Edition version).

The calculation of the S/N is based on the range of the noise in a chromatogram obtained after injection of a blank (diluent), observed over a distance equal to at least 5 times the width at half-height of the peak (at least 5 × Wh) in the chromatogram obtained with the reference solution.