title: Improved sensitivity by use of gas chromatography-positive chemical ionization triple quadrupole mass spectrometry for the analysis of drug related substances.
abstract: In 2013, the World Anti-Doping Agency (WADA) drastically lowered the minimum required performance levels (MRPLs) of most doping substances, demanding a substantial increase in sensitivity of the existing methods. For a number of compounds, conventional electron impact ionization gas chromatography tandem mass spectrometry (GC-EI-MS/MS) is often no longer sufficient to reach these MRPLs and new strategies are required. In this study, the capabilities of positive ion chemical ionization (PICI) GC-MS/MS are investigated for a wide range of drug related compounds of various classes by injection of silylated reference standards. Ammonia as PICI reagent gas had superior characteristics for GC-MS/MS purposes than methane. Compared to GC-EI-MS/MS, PICI (with ammonia as reagent gas) provided more selective ion transitions and consequently, increased sensitivity by an average factor of 50. The maximum increase (by factor of 500-1000) was observed in the analysis of stimulants, namely chlorprenaline, furfenorex and phentermine. In total, improved sensitivity was obtained for 113 out of 120 compounds. A new GC-PICI-MS/MS method has been developed and evaluated for the detection of a wide variety of exogenous doping substances and the quantification of endogenous steroids in urine in compliance with the required MRPLs established by WADA in 2013. The method consists of a hydrolysis and extraction step, followed by derivatization and subsequent 1μL pulsed splitless injection on GC-PICI-MS/MS (16min run). The increased sensitivity allows the set up of a balanced screening method that meets the requirements for both quantitative and qualitative compounds: sufficient capacity and resolution in combination with high sensitivity and short analysis time. This resulted in calibration curves with a wide linear range (e.g., 48-9600ng/mL for androsterone and etiochanolone; all r(2)>0.99) without compromising the requirements for the qualitative compounds.
authors: Ghent University, Department of Clinical Chemistry, Microbiology and Immunology, Doping Control Laboratory, Technologiepark 30 B, B-9052 Zwijnaarde, Belgium.
authors: Wim
authors: W
authors: Van Gansbeke
authors: Ghent University, Department of Clinical Chemistry, Microbiology and Immunology, Doping Control Laboratory, Technologiepark 30 B, B-9052 Zwijnaarde, Belgium. Electronic address: michael.polet@UGent.be.
authors: Michael
authors: M
authors: Polet
authors: Ghent University, Department of Clinical Chemistry, Microbiology and Immunology, Doping Control Laboratory, Technologiepark 30 B, B-9052 Zwijnaarde, Belgium.
authors: Fiona
authors: F
authors: Hooghe
authors: Research Institute for Chromatography (RIC), President Kennedypark 26, B-8500 Kortrijk, Belgium.
authors: Christophe
authors: C
authors: Devos
authors: Ghent University, Department of Clinical Chemistry, Microbiology and Immunology, Doping Control Laboratory, Technologiepark 30 B, B-9052 Zwijnaarde, Belgium.
authors: Peter
authors: P
authors: Van Eenoo
mesh_terms: D004300:Doping in Sports; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D057230:Limit of Detection; D004364:Pharmaceutical Preparations / Q000032:analysis*; D012015:Reference Standards
chemical_list: D004364:Pharmaceutical Preparations
keywords: Chemical ionization; Doping; GC–MS/MS; Sensitivity