Ultra high performance supercritical fluid chromatography coupled with tandem mass spectrometry for screening of doping agents. I: Investigation of mobile phase and MS conditions

•Sensitivities and peak shapes were compared in UHPLC–MS/MS and UHPSFC–MS/MS.•10 mM ammonium formate can be considered a suitable mobile phase additive for UHPSFC–MS/MS operation.•For interfacing UHPSFC and MS/MS, ethanol can be used as generic make-up solvent.•The impact of operating parameters on MS sensitivity was different with acidic and basic compounds.

The conditions for the analysis of selected doping substances by UHPSFC–MS/MS were optimized to ensure suitable peak shapes and maximized MS responses. A representative mixture of 31 acidic and basic doping agents was analyzed, in both ESI+ and ESI− modes. The best compromise for all compounds in terms of MS sensitivity and chromatographic performance was obtained when adding 2% water and 10 mM ammonium formate in the CO2/MeOH mobile phase. Beside mobile phase, the nature of the make-up solvent added for interfacing UHPSFC with MS was also evaluated. Ethanol was found to be the best candidate as it was able to compensate for the negative effect of 2% water addition in ESI− mode and provided a suitable MS response for all doping agents.Sensitivity of the optimized UHPSFC–MS/MS method was finally assessed and compared to the results obtained in conventional UHPLC–MS/MS. Sensitivity was improved by 5–100-fold in UHPSFC–MS/MS vs. UHPLC–MS/MS for 56% of compounds, while only one compound (bumetanide) offered a significantly higher MS response (4-fold) under UHPLC–MS/MS conditions.In the second paper of this series, the optimal conditions for UHPSFC–MS/MS analysis will be employed to screen >100 doping agents in urine matrix and results will be compared to those obtained by conventional UHPLC–MS/MS.

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