Rapid Determination of Chloramphenicol in Honey by Laser Diode Thermal Desorption Using Atmospheric Pressure Chemical Ionization-Tandem Mass Spectrometry

A high-throughput, rapid, and reliable method based on laser diode thermal desorption (LDTD) and atmospheric pressure chemical ionization coupled to tandem MS (APCI-MS/MS) was used to identify and quantify chloramphenicol (CAP) residues in honey. Sample pretreatment consisted of a liquid-liquid extraction of diluted honey in water with ethyl acetate containing stearic acid. After extraction, a 2 mu L aliquot of the organic phase was deposited into a 96-well plate prior to detection by LDTD-APCI-MS/MS. The total analysis time was less than 6 s compared to several minutes for traditional chromatographic methods used for CAP detection, since no chromatographic separation was necessary. The extraction and analysis were made with honey samples of different color grading ranging from extra white to dark amber. The method showed good linearity (R-2 = 0.99995) within a concentration range of 0.1 to 500 ng/g for CAP with D-5-CAP as an internal standard. The RSD varied between 8 and 24% over the calibration range (n = 4). The method LOD for CAP in honey was 0.19 ng/g. This work demonstrates that LDTD-APCI-MS/MS could be used for fast and effective quantification of CAP in honey samples.