https://doi.org/10.1351/goldbook.09902
Width of a peak (\(f + b\)) divided by twice the width of the front of the peak (\(f\)), measured at \(\pu{10\%}\) of the peak height (see figure). \[A_{\rm{s}} = \frac{(f + b)}{2f}\]

Peak asymmetry (schematic). \(R_{\rm{D}}\) is the response of the detector.
Notes:
- For a symmetrical peak \(A_{\rm{s}} = 1\).
- Some pharmacopoeia definitions of peak asymmetry measure the value at \(\pu{5\%}\) of the peak height.
See also: tailing factor