- Acknowledgements: The authors gratefully acknowledge the financial support of the Andalusian Government (Junta de Andalucía) for supporting this work (Excellence Project ref: P12-AGR-1647). Maykel Hernández-Mesa thanks the Plan Propio of the University of Granada for a predoctoral contract.
- Authors: M. Hernández-Mesa, C. Cruces-Blanco, A.M. García-Campaña.
- Reference: Talanta 163 (2017) 111-120.
A novel capillary electrophoresis-tandem mass spectrometry approach is proposed for the determination of eleven 5-nitroimidazoles in urine samples for therapeutical drug monitoring purposes. A comparison between two separation modes, namely micellar electrokinetic chromatography and capillary zone electrophoresis was carried out, obtaining higher selectivity when 1 M formic acid (pH 1.8) was selected as background electrolyte. 5-Nitroimidazoles were hydrodynamically injected in water for 40 s at 50 mbar and their separation was performed at 28 kV and 25 °C. To improve migration time repeatability, a pressure of 50 mbar was applied to the inlet vial during runs without any loss of peak resolution. Electrospray ionization parameters were established as follow: 6 L/min, dry gas flow rate; 51,021.2 Pa, nebulization pressure; 160 °C, dry gas temperature. Sheath liquid consisted of a mixture of propan-2-ol/water/acetic acid (60.0:38.8:0.2% v/v/v) supplied at 3.3 µL/min. MS parameters were optimized for analyte identification through their MS2 and MS3 spectra. The method was applied to the determination of 5-nitroimidazoles in urine samples, applying molecularly imprinted solid phase extraction for sample clean-up. Recoveries higher than 79.2% demonstrated the suitability of the procedure. Limits of detection ranged from 9.6 to 130.2 µg/L while precision assays resulted in relative standard deviations for peak areas lower than 16.1%.
