The analysis of honey samples for residues of nitrobenzene and petroleum from the possible use of Frow mixture in hives

A headspace gas chromatography–mass spectrometry method has been established for the analysis of honey samples for nitrobenzene and petroleum residues. These substances may be used as components of ‘Frow mixture’ applied to treat hives for the control of Acarine (infestation by parasitic mites) in honey bees. The method had a detection limit of 2 μg/kg for nitrobenzene and 0.5 μg/kg (or better) for four indicator substances of petroleum—toluene, o-xylene, ethylbenzene and naphthalene. The method was applied in a small survey of 49 retail honey samples. No sample contained detectable nitrobenzene or petroleum residues defined as the presence of all four indicator hydrocarbons. Two honey samples contained low levels of toluene (19 and 62 μg/kg) and one of these two samples also contained o-xylene (2 μg/kg). The origin of these very low levels was not investigated. These analytical findings indicate that, for honey samples entering the UK market, either the use of Frow mixture to fumigate bee hives is not commonly practiced or that chemical residues from the treatment are not persistent.