title: Use of mathematical derivatives (time-domain differentiation) on chromatographic data to enhance the detection and quantification of an unknown 'rider' peak.
abstract: 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.
authors: Cancer Research UK Formulation Unit, Department of Pharmaceutical Sciences, University of Strathclyde, 204 George Street, Glasgow, Scotland G1 1XW, UK. crcfus@strath.ac.uk
authors: S J
authors: SJ
authors: Ford
authors: M A
authors: MA
authors: Elliott
authors: G W
authors: GW
authors: Halbert
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004340:Drug Contamination / Q000706:statistics & numerical data*; D008432:Mathematical Computing; D015203:Reproducibility of Results