Determination of Dicyclohexylamine and Fumagillin in Honey by LC-MS/MS

A reversed phase (RP) liquid chromatography tandem mass spectrometric (LC-MS/MS) method was developed and validated to confirm and quantitate trace levels of fumagillin and dicyclohexylamine (DCH) residues in honey destined for human consumption. Chromatographic resolution of DCH and fumagillin, including the latter's biologically active UV degradation products, was achieved using a C18 analytical column. A deuterium labelled d(10)-DCH internal standard was synthesized in a one-pot reaction from readily available starting materials and was used to compensate for observed matrix affects when quantitating DCH in honey from different floral origins. Sample extraction was achieved by using reversed phase polymeric solid phase extraction (SPE) with recoveries (+/- RSD%) at 10, 100 and 500 ng g(-1) for 18 replicates at each respective concentration calculated as 105.7 +/- 10.8, 100.8 +/- 9.3 and 104.3 +/- 8.7 for fumagillin and as 104.0 +/- 5.9, 98.3 +/- 6.9 and 104.0 +/- 9.7 for DCH. Domestically produced honey samples (n = 16) were analyzed for fumagillin and DCH, and screened for UV-decomposed fumagillin, without having any prior knowledge of whether fumagillin was used in the bee colonies from which the honeys were produced. No UV-decomposed fumagillin could be detected in any of the samples. Fumagillin was detected in 11 of the 16 samples at levels below 10 ng g(-1), and only in 2 samples at levels above 10 ng g(-1) (11.9 and 11.6 ng g(-1), respectively). DCH was detected in all of the tested samples with concentrations above 10 ng g(-1) being observed for 15 out of the 16 samples, with concentrations ranging from 20.0 to 234.6 ng g(-1).