Liquid-phase microextraction for sample preparation in analysis of unconjugated anabolic steroids in urine

• Published in: Analytica chimica acta Vol. 559; no. 2; pp. 166 - 172
• Main Authors: Leinonen, Antti, Vuorensola, Katariina, Lepola, Laura-Maria, Kuuranne, Tiia, Kotiaho, Tapio, Ketola, Raimo A., Kostiainen, Risto
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 16-02-2006; Elsevier
• Subjects: Anabolic steroids; Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Derivatization; Exact sciences and technology; Extraction techniques; Gas chromatographic methods; Gas chromatography; Hollow fibers; Liquid chromatography; Liquid-phase microextraction; Mass spectrometry; Other chromatographic methods; Spectrometric and optical methods; Gas chromatography; Liquid-phase microextraction; Hollow fibers; Extraction techniques; Anabolic steroids; Liquid chromatography; Derivatization; Mass spectrometry; Steroid; Metabolite; Internal standard; Silylation; Microanalysis; Liquid phase; Solvent extraction; Chemical enrichment; Sample preparation; Hollow fiber; Urine; Sensitivity analysis; Filtration; Coupled method; Propylene polymer; Hydrophobic compound; Gas chromatography: Mass spectrometry; Repeatability; Organic solvent; Linearity; Microextraction
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2005.12.004

The applicability of in-vial two-phase liquid-phase microextraction (LPME) in porous hollow polypropylene fiber was studied for the sample preparation of unconjugated anabolic steroids in urine. Four different anabolic steroids – metabolites of fluoxymesterone, 4-chlorodehydromethyltestosterone, stanozolol and danazol – were used as test compounds and methyltestosterone as an internal standard. A standard two-phase LPME method for use with liquid chromatography/mass spectrometry (LC/MS) was set up and the influence of different parameters, including the nature of organic solvent, extraction time, salting-out and temperature, on the LPME process was investigated. Taking advantage of the preliminary studies, a novel two-phase LPME method utilizing simultaneous in-fiber silylation was developed and validated for gas chromatographic/mass spectrometric (GC/MS) analysis of a danazol metabolite in urine. In all, LPME allowed a very straightforward, simple and selective way to prepare urine samples for steroid analysis, being most suitable for hydrophobic steroids. The LPME method with in-fiber derivatization for GC/MS analysis exhibited high sensitivity, repeatability and linearity and enabled simultaneous filtration, extraction, enrichment and derivatization of the analyte from urine matrix without any other steps in sample pretreatment.