Rapid determination of chloramphenicol and its glucuronide in food products by liquid chromatography–electrospray negative ionization tandem mass spectrometry

Chloramphenicol (CAP) is subjected to monitoring in food products, with a minimum required performance level set at 0.3 ng/g. CAP was isolated from chicken meat and seafood by very simple solvent extraction procedure. For honey, a fast SPE procedure was applied. CAP-D5 was used as internal standard. HPLC separation was done on RP18 123 mm×3 mm column in acetonitrile–ammonium formate 10 mM, pH 3.0 (40:60) at flow rate of 0.3 ml/min. A TSQ Quantum instrument with ESI source has been used in negative ionization mode. A MRM procedure has been applied and following transitions were monitored: m/z 321>152 (quantifier), 321>194, 321>257 (qualifiers), 326>157 (IS). CAP peak was eluted at around 5 min; the total run time was 7 min. LOD was around 0.1 ng/g meat or 0.05 ng/g honey. Matrix effects were studied for all materials used, involving injection of blank extracts with post-column infusion of CAP, as well as checking the influence of the co-injected blank extracts on the signal intensity of CAP. No influence of matrix on the results of CAP determination were observed. The method allows analyzing up to 30 duplicate samples per day, including all calibration standards. Additionally, the method for determination of CAP glucuronide (CAP-G) was established, using urine from rats that were given this drug as a source of the metabolite. Full validation of the metabolite was not possible, due to the unavailability of reference standard.