[Analysis of chloramphenicol in propolis extract by LC/MS/MS]

A quantitative analysis method using LC/MS/MS of chloramphenicol (CAP) in propolis extract (ethanol extract) has been established. Extraction of CAP from propolis extract was performed by adding water, followed by salting-out with sodium chloride. Through this procedure, the wax components of propolis extract could be effectively removed. LC separation was performed with a reverse-phase column (Mightysil RP-18 GP Aqua, 2.0 mm x 150 mm, 5 microm), using 10 mmol/L of ammonium acetate-acetonitrile (75 : 25) as a mobile phase. The flow rate was 0.2 mL/min. Ionization was performed by electrospray ionization (ESI) in the negative mode. The detection and quantification limits of CAP in propolis extract were 0.05 and 0.15 ng/g, respectively, and the recovery rate (spiked CAP level was 0.5 ng/g) was 111.2%. When eight samples of propolis extract products on the market were analyzed using this method, CAP was not detected (N.D.) in any of the samples.