Comparison of the transfer of coumaphos from beeswax into syrup and honey

(Received 22 May 2000; revised 30 October 2000; accepted 7 November 2000)

Abstract
The organophosphate insecticide coumaphos has recently received emergency approval in the United States for control of fluvalinate-resistant Varroa destructor and the small hive beetle, Aethina tumida Murray. We investigated the transfer of coumaphos from wax into syrup and honey, using adsorption of coumaphos from diluted syrup or honey onto a solid-phase extraction cartridge, elution, and subsequent analysis. Coumaphos in syrup was quantitated using HPLC with UV detection, and we found that coumaphos migrates from wax into syrup, with low concentrations increasing over a few months. Concentrations reached 200-300 ppb in 100 g of syrup in contact with 10 g of wax containing 1000 ppm of coumaphos; contact with wax containing 100 and 10 ppm led to lower amounts. Impurities made HPLC determination of coumaphos in honey impossible, but the solid phase extract could be analyzed by gas chromatography/mass spectrometry. Concentrations in honey were similar to those in syrup, reaching 430 ppb after 26 weeks at 1000 ppm in wax.