Sensitive detection of 3'-hydroxy-stanozolol glucuronide by liquid chromatography-tandem mass spectrometry

Stanozolol is one of the most frequently detected anabolic steroids in doping control samples. This compound is metabolized to a large extent and its metabolites can be detected in urine much longer than the parent compound. The main stanozolol metabolites are excreted in urine as glucuronide conjugates and 3'-hydroxy-stanozolol glucuronide (3STANG) is one of the most important in human urine. Therefore enzymatic hydrolysis is usually applied prior to extraction. In this article a method for the sensitive detection of intact 3'-hydroxy-stanozolol glucuronide, by liquid chromatography tandem mass spectrometry, is described. The method takes advantage of an easy and fast sample preparation based on a single solid-phase extraction avoiding enzymatic hydrolysis or derivatization. It allows to detect stanozolol abuse in human urine at 25pgmL(-1). The method was validated according to Eurachem guidelines. The matrix effect, expressed as ion enhancement was +14%. The extraction recovery of the method was 93%. The limit of detection (LOD), whereby all WADA-criteria in chromatography and mass spectrometry are fulfilled, was determined at 50pgmL(-1). Application of the method to an excretion study revealed that the 3'-hydroxy-stanozolol glucuronide could be confirmed for 10 days after oral administration of 2mg of stanozolol, prolonging detection times compared to other metabolites and methodologies by almost 50%.