Determination of Dicyclohexylamine in Beeswax by Aqueous Normal Phase Liquid Chromatography Coupled With Tandem Mass Spectrometry.

Dicyclohexylamine (DCH) is an excipient present in commercial formulations of fumagillin (Fumagilin-B® and Fumidil-B®), an antibiotic which is employed in apiculture for the control of nosema disease. DCH has been demonstrated to be stable in harvested honey; however, its fate in the beehive has not been investigated. In this study, DCH residues were determined in beeswax samples collected from brood chambers and honey supers from various apiaries throughout Alberta. The determination of DCH was performed using a simple extraction procedure followed by low-temperature cleanup and finally analysis with aqueous normal phase liquid chromatography-electrospray ionization tandem mass spectrometry. The method was found to yield high accuracy and precision (94.9 ± 1.7% to 110.8 ± 6.6%) for replicate beeswax samples spiked with 4, 80, 360 and 2,000 μg kg-1 of DCH. With a limit of quantification of 1 μg kg-1, 100% of the 61 beeswax samples analyzed were found to contain residues of DCH ranging from 15 to 6,410 μg kg-1. The results indicate that DCH can accumulate in beeswax when Fumagilin-B® or Fumidil-B® is applied in apiculture and that these concentrations can vary significantly among beekeeping operations.