Development of a capillary gas chromatographic method with flame ionisation detection for the simultaneous determination of sildenafil and itsN-demethylated metabolite in biological fluids

Abstract

A simple, rapid, and sensitive method has been developed for the analysis of sildenafil (S) and its N-Demethylated metabolite UK-103,320 (UK) using capillary gas chromatography with a flame ionisation detector. Optimal conditions were investigated, achieving analysis times shorter than 12 minutes. Aspects such as stability of the solutions, linearity, accuracy (<91%), precision, specificity, and limits of detection (0.02 mg/L and 0.12 mg/L for S and UK respectively) were tested in order to validate the method. A solid-phase extraction (SPE) prior to the analysis allows quantification of S in serum and urine, and UK in serum at clinically relevant concentrations. Furthermore the specificity has been assessed by means of mass spectrometry in SCAN mode.