On-line immunoaffinity chromatography—high-performance liquid chromatography—mass spectrometry for the determination of dexamethasone

Abstract

The determination of the synthetic corticosteroid dexamethasone in equine urine is described using coupled on-line immunoaffinity chromatography–high-performance liquid chromatography (IAC–HPLC) with detection by UV or mass spectrometry. The limit of detection for dexamethasone with UV detection was 30 µg l^–1 for a 10 ml urine sample. Atmospheric pressure chemical ionization mass spectrometry, with single ion monitoring, gave a limit of detection of 0.1 µg l^–1 for dexamethasone. The determination of dexamethasone by on-line IAC–HPLC–MS has been demonstrated in post-administration equine urine samples.