Multi-laboratory study of the analysis and kinetics of stanozolol and its metabolites in treated calves

The European Union banned the use of anabolic steroids for cattle fattening in 1988. Analytical techniques able to detect trace amounts of the parent drugs and their metabolites are mandatory for the control of abuse. Stanozo lol (Stan) is an anabolic steroid that is often found in injection sites an d cocktails. However, it has never been detected in tissues (kidney fat, me at) or excreta (urine, faeces) taken during regulatory inspection. The diff erence between the structure of Stan and the other steroids (a pyrazole rin g fused to the androstane ring system) is probably the cause of this phenom enon. In the multi-laboratory study described here, veal calves were treate d with intramuscular doses of Stan. In the excreta of these calves the pres ence, absence and/or concentration of Stan and of its major metabolites 16 beta-hydroxystanozolol and 3'-hydroxystanozolol were determined. For the de termination of these analytes the different laboratories used different ext raction and clean-up procedures and also evaluated different analytical tec hniques such as CC-MS (negative chemical ionization) and LC-MS-MS. The aim of this investigation was to explore which analyte should be validated for veterinary inspection purposes.