Modified resolution factor for asymmetrical peaks in chromatographic separation.
The quality of separation is measured by resolution factor (R(s)) between adjacent peaks. The current United States Pharmacopeia (USP) method for R(s) calculation assumes symmetrical peak shapes. In practice, perfectly symmetrical peaks are rarely encountered. The goal of this study was to correct the inaccuracy due to peak asymmetry by using a new formula for R(s) calculation. Peak tailing factor was incorporated into the formula for the calculation of R(s) to correct for the peak asymmetry. The resulting modified formula was compared with USP formula using simulated peaks and actual peaks. Through mathematical derivation, the modified R(s) was expressed as: R=[2(t(2)+W(2)/2(1-1/TF(2))-t(1)-W(1)/2(1-1/TF(1)))]/W(1)+W(2) where t(1) and t(2) are the retention times of two peaks, W(1) and W(2) are peak widths at baseline, TF(1) and TF(2) are USP tailing factors. All parameters used in the formula are available from commercial data analysis software. Comparisons of modified R(s) to USP R(s) showed that the modified R(s) provided a more accurate measure of peak separation at the baseline level.
Song
Di
D
Genetics Institute, Drug Safety and Metabolism, Wyeth-Ayerst Research, Andover, MA 01810, USA. dsong@genetics.com
Wang
Juan
J
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004364:Pharmaceutical Preparations / Q000737:chemistry
D004364:Pharmaceutical Preparations