DETERMINATION OF CHLORAMPHENICOL RESIDUES IN HONEY BY MONOLITHIC COLUMN LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY AFTER USE OF QUECHERS CLEAN-UP

SUMMARY An HPLC method with a monolithic column and detection by mass spectrometry has been established for determination of chloramphenicol in honey samples previously cleaned by use of a modification of the QuEChERS procedure. Honey samples were dissolved in water containing sodium chloride and extracted with acetonitrile. Further sample clean-up was performed by simple reversed-solid-phase dispersion with primary–secondary amine (PSA) adsorbent. Chloramphenicol (CAP) residues at ppb concentrations were detected by liquid chromatography–mass spectrometry (LC–MS), with electrospray ionization, in negative-ion mode. The mobile phase was methanol–0.2% aqueous ammonium acetate solution, 45:55 (v/v). Under these conditions CAP is eluted after ~4 min and 8 min from a Merck RP18e monolithic column and a conventional C18 column, respectively. Recovery at three fortification levels (0.2, 20, and 200 µg kg −1 ) was in the range 78–93% with RSD from 3.7 to 3.9%. The coefficient of determination, R 2 , was 0.9995 over a 0.1–100 µg L −1 linear range. Use of this method for determination of CAP in honey resulted in an LCL of 0.20 µg kg −1 . The method was validated on the basis of EU decision 2002/657. CCα and CCβ for the honey matrix were 0.002 and 0.006 µg kg −1 , so the method was fit for the purpose of monitoring commercial products or checking MRL compliance.