Determination of 16 beta-hydroxystanozolol in urine and faeces by liquid chromatography-multiple mass spectrometry

This paper describes the optimisation of the detection of stanozolol and it s major metabolite 16 beta -hydroxystanozolol in faeces and urine from catt le. Faeces are extracted directly with diisopropyl ether. Urine is first su bmitted to an enzymatic hydrolysis and then extracted over a modified diato maceous earth column (Chem-Elut) with a mixture of diisopropyl ether-isooct ane. In a final step an acidic back extraction is performed. For the LC-MS- MS detection two approaches are discussed. In a first approach the final ex tract is detected without derivatization, while the second approach makes u se of a derivatization step for 16 beta -hydroxystanozolol. While the MS-MS spectrum without derivatization exhibits extensive fragmentation, the spec trum of the derivative shows two abundant diagnostic ions with much more re producible ion ratios. The derivatization method and the method without der ivatization enable the detection of 16 beta -hydroxystanozolol up to 0.03 m ug l(-1) in urine and 0.07 mug kg(-1) in faeces. Until now there is no lite rature available for the detection of 16 beta -hydroxystanozolol in faeces and urine at the ppt level. (C) 2000 Elsevier Science B.V. All rights reser ved.