- 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) and Spanish Ministry of Economy and Competitiveness (Project Ref: AGL2015-70708-R). CTC thanks the predoctoral fellowship associated to the Excellence Project Ref: P12-AGR-1647. FJL is grateful for personal funding through the Special Research Program of the University of Granada.
- Authors: C. Tejada-Casado, M. del Olmo-Iruela, A.M. García-Campaña, F.J. Lara.
- Reference: Journal of Chromatography B 1091 (2018) 46-52.
A green and simple multiresidue method using capillary liquid chromatography (CLC) with UV-diode array detection (DAD) has been developed for the determination of sixteen benzimidazoles (BZs) and its metabolites in milk samples. The separation was achieved in <32 min, using a Zorbax XDB-C18 column (150 mm × 0.5 mm I.D, 5 μm), with a mobile phase consisting of 50 mM ammonium acetate (solvent A) and a mixture of acetonitrile/methanol (1:1 v/v) (solvent B), at a flow rate of 9 μL min−1. The temperature of the column was 20 °C and 6 μL of sample were injected. In spite of the complexity of milk samples, an effective, simple and fast sample preparation method called salting out-assisted liquid-liquid extraction (SALLE) was developed for the analysis of these compounds in cow milk samples. To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized including the amount of sample, type and volume of the extraction solvent, and the nature and amount of the salt. Good linearity was obtained (R2 > 0.9985 for all BZs) with limits of detection (LOD) between 1.0 and 2.8 μg kg−1. Relative standard deviations of repeatability and intermediate precision were below 1.6 and 14.2%, respectively. Satisfactory recoveries between 79.1 and 99.6% were also obtained for three types of milk samples (cow, sheep and goat). The advantages of a miniaturized technique such as CLC in terms of better efficiencies and reduced solvent consumption, combined with the simplicity of the SALLE procedure, make this method a useful alternative for the monitoring of these residues at trace level.
