Comparison of immunoaffinity chromatography combined with gas chromatography—negative ion chemical ionisation mass spectrometry and radioimmunoassay for screening dexamethasone in equine urine

Pharmacokinetics of dexamethasone with pharmacokinetic/pharmacodynamic model of the effect of dexamethasone on endogenous hydrocortisone and cortisone in the horse

“…Numerous methods such as radioimmunoassay, immunoaffinity chromatography, gas chromatography, immunoassay, HPLC, and LC-MS have been developed for the screening and confirmation of DXM and other steroids in equine post-race urine samples (Skrabalak et al, 1984;Friedrich et al, 1992;Stanley et al, 1993;Gu et al, 1996;Ribeiro Neto et al, 1997a,b;Grippa et al, 2000;Tang et al, 2001). These methods were developed for screening and confirmation for forensic purposes and were not specific or sufficiently sensitive for the adequate determination of pharmacokinetics of DXM in the equine.…”

Direct-injection screening for acidic drugs in plasma and neutral drugs in equine urine by differential-gradient LC–LC coupled MS/MS

“…The more potent synthetic corticosteroids were detected at the 1 ng/ml level and this is compatible with the 2 ng/ml dexamethasone Minimum performance criteria that was established by the International Federation of Horseracing Authorities in Article 6 of the IABRW [14]. This LOD is also effective from a practical viewpoint as, for example, the urine level for an intra-muscular administration of 26 mg of dexamethasone sodium phosphate was reported as 1.2 ng/ml in a 48 h urine sample [22]. Therefore, this direct-injection screening method would give a detection period for dexamethasone IM administration that would cover the period over which this drug is expected to exert a marked effect on the racehorse.…”

Past, present and future of mass spectrometry in the analysis of residues of banned substances in meat‐producing animals

“…For many years, various analytical methods have been proposed for the identification of CoST residues in various biological matrices. During the 1980s and early 1990s, the main detection methods used for CoSTs were radioimmunology,30, 31 fluorimetry (after HPLC or TLC)32, 33 or liquid chromatography with UV detection 34–38. Nowadays, mass MS coupled to GC or LC is the method of choice for the unambiguous identification of these compounds at trace level in biological matrices.…”

“…The last chemical reaction permitting the GC‐MS analysis of CoST is the elimination of the polar C 17 side chain by chemical oxidation and the subsequent oxidation of residual hydroxyl groups to ketone functions. This technique was the most commonly used one before the development of LC‐MS n systems 31, 40, 41, 44–46, 66. In Fig.…”