Qualitative detection of desmopressin in plasma by liquid chromatography-tandem mass spectrometry

This work describes a liquid chromatography-electrospray tandem mass spectrometry method for detection of desmopressin in human plasma in the low femtomolar range. Desmopressin is a synthetic analogue of the antidiuretic hormone arginine vasopressin and it might be used by athletes as a masking agent in the framework of blood passport controls. Therefore, it was recently added by the World Anti-Doping Agency to the list of prohibited substances in sport as a masking agent. Mass spectrometry characterization of desmopressin was performed with a high-resolution Orbitrap-based mass spectrometer. Detection of the peptide in the biological matrix was achieved using a triple-quadrupole instrument with an electrospray ionization interface after protein precipitation, weak cation solid-phase extraction and high performance liquid chromatography separation with an octadecyl reverse-phase column. Identification of desmopressin was performed using three product ions, m/z 328.0, m/z 120.0, and m/z 214.0, from the parent ion, m/z 535.5. The extraction efficiency of the method at the limit of detection was estimated as 40% (n = 10), the ion suppression as 5% (n = 10), and the limit of detection was 50 pg/ml (signal-to-noise ratio greater than 3). The selectivity of the method was verified against several endogenous and synthetic desmopressin-related peptides. The performance and the applicability of the method were tested by analysis of clinical samples after administration of desmopressin via intravenous, oral, and intranasal routes. Only after intravenous administration could desmopressin be successfully detected

From amanita muscaria to somatotropine : the doping story

This article reviews history of application of doping substances and methods in sport. Some new doping agents such as erythropoietin (EPO), human chorionic gonadotropin (hCG), growth hormone (GH) and other, challenging doping control laboratories all over the world, are also discussed

Disposition of human drug preparations in the horse, V : orally administered oxprenolol

Urinary concentrations of the beta-antagonist oxprenolol and some of its major human metabolites were determined following oral administration of a dose of 160 mg to five fasted horses, Quantitation was performed by gas chromatography-mass spectrometry (GC-MS) in the selected ion mode (SIM) by monitoring ion m/z 466, of the heptafluorobutyric derivatives, As early as 2 h after dosage oxprenolol could be detected in hydrolysed urine and remained detectable up to 24 h. Maximum urinary concentrations and excretion rates were obtained between 2 and 12 h, After 12 h only 2.8% of the administered dose was excreted as conjugates of oxprenolol and major human metabolites including: 4-OH-oxprfnolol and 5-OH-oxprenolol. These metabolites were detectable up to 48 h