Methods for evaluating peak tailing:
(1) tailing factor, Tf (US Pharmacopeia)
(2) peak asymmetry factor, As
Parameters for the tailing factor:
(1) peak height
(2) peak width at 5% of the peak height from baseline
(3) width of the front half of the peak at 5% of the peak height from baseline
tailing factor =
= (peak width) / (2 * (front half width))
Parameters for the peak asymmetry factor:
(1) peak height
(2) width of the front half of the peak at 10% of the peak height from baseline
(3) width of the back half of the peak at 10% of the peak height from baseline
peak asymmetry factor =
= (back half width) / (front half width)
Interpretation:
• Under ideal circumstances, both measures should be 1.
• As tailing increases, both measures will increase.
• As a rule of thumb, a system with either factor <= 1.5 is usually not worth trying to improve.
