Quantitative analysis of chloramphenicol, thiamphenicol, florfenicol and florfenicol amine in eggs via liquid chromatography-electrospray ionization tandem mass spectrometry.

A widely applicable method involving liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (LC-ESI/MS/MS) was developed for the simultaneous determination of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in eggs. Samples were extracted with ethyl acetate-acetonitrile-ammonium hydroxide (49:49:2, v/v) and defatted with hexane saturated with acetonitrile. The analysis was carried out on a mass spectrometer via an electrospray interface operated in the positive and negative ionization modes using deuterated chloramphenicol-d5 as the internal standard. The limits of detection and limits of quantification were 0.04-0.5 μg/kg and 0.1-1.5 μg/kg in eggs, respectively. The average recoveries of the four analytes from egg samples were 90.84-108.23%, with relative standard deviations of less than 9.61%. The corresponding intra-day and inter-day variations were found to be less than 8.11% and 11.30%, respectively. Finally, the new approach was successfully applied to the quantitative determination of these analytes in 50 commercial eggs from local supermarkets.