Use of mathematical derivatives (time-domain differentiation) on chromatographic data to enhance the detection and quantification of an unknown 'rider' peak.
Two samples of an anticancer prodrug, AQ4N, were submitted for HPLC assay and showed an unidentified impurity that eluted as a 'rider' on the tail of the main peak. Mathematical derivatization of the chromatograms offered several advantages over conventional skimmed integration. A combination of the second derivative amplitude and simple linear regression gave a novel method for estimating the true peak area of the impurity peak. All the calculation steps were carried out using a widely available spreadsheet program.
Ford
S J
SJ
Cancer Research UK Formulation Unit, Department of Pharmaceutical Sciences, University of Strathclyde, 204 George Street, Glasgow, Scotland G1 1XW, UK. crcfus@strath.ac.uk
Elliott
M A
MA
Halbert
G W
GW
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004340:Drug Contamination / Q000706:statistics & numerical data*; D008432:Mathematical Computing; D015203:Reproducibility of Results