Multi-residue determination of b-agonists in bovine muscle using dispersive liquid liquid microextraction by +esi tandem mass spectrometry

Abstract

A dispersive liquid-liquid microextraction (DLLME) method has been developed, optimized and validated for the extraction of seven beta-agonists (Cimaterol, Cimbuterol, Clenproperol, Clenbuterol, Ractopamine, Isoxsuprine and Ritodrine) from bovine muscle. The homogenized tissue samples were hydrolyzed enzymaticaly by beta-glucuronidase and extracted with DLLME. The extraction parameters (pH, extraction solvent, extraction solvent volume, disperser solvent) were accurately optimized. Separation of the beta-agonists was by gradient elution on C18 LC column using acetonitrile and formic acid aqueous solutions as mobile phases, multiple reaction monitoring (MRM) scan mode was used. The seven beta-agonists were then simultaneous determined and identified in single analysis using 4000 Qtrap LC-MS/MS system. The DLLME method was validated using ISO 17025 and the EU criteria (Commission Decision 2002/657/EC) for validation of analytical method, good precision, repeatability and spiked recoveries were obtained. The limits of detection and quantification for the residues were between 0.0728 – 0.0922 μg/kg and 0.243 – 0.307 μg/kg respectively for beta-agonists. The overall recoveries were between 85% and 100% with the relative standard deviation of (RSDs) between 3.0% and 10%. The recoveries from the developed DLLME method were compared with those obtained from dSPE. DLLME proved to be comparable to SPE. The real samples test showed that the DLLME method developed is accurate and sensitive for the determination of beta-agonist residues in bovine muscle.