DETECTION OF CORTICOSTEROIDS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY NEGATIVE-ION CHEMICAL-IONIZATION MASS-SPECTROMETRY USING A PARTICLE-BEAM INTERFACE

A normal-phase high-performance liquid chromatographic/particle beam m ass spectrometric (negative chemical ionization) method has been devel oped for the detection of synthetic corticosteroids (SC). Characterist ic and reproducible full-scan spectra were obtained for the SC analyse d. The limit of detection using selected ion monitoring for the molecu lar anion of beclomethasone was 500 pg. Urine from an equine to which 9 alpha-fluoroprednisolone acetate had been administered was extracted by immunoaffinity chromatography and analysed by high-performance liq uid chromatography-ultraviolet detection/particle beam mass spectromet ry. Full-scan spectral data from these extracts allowed positive ident ification of 9 alpha-fluoroprednisolone (isoflupredone) in the equine urine up to 96 h post administration.