Investigation of naphthalene contamination in olive oil from Greece

Abstract

Incidents of using naphthalene in olive orchards as a repellent of olive fly (Bactrocera oleae) have recently been recorded. Naphthalene, the primary ingredient of mothballs, is described to be diluted in plastic bottles and hanged on the trees releasing its characteristic odor which is supposed to repel olive fly. Since naphthalene has been characterized as possibly carcinogenic to humans and animals, it was considered essential to monitor olive oils regarding their potential contamination with this specific pollutant. To this goal, a simple, sensitive and reliable analytical method for the determination of naphthalene in olive oil has been developed. The method involves extraction with ethyl acetate: acetonitrile (1:1) and determination of naphthalene using gas chromatography triple quadrupole mass spectrometry. The method was validated in four fortification levels, 0.005, 0.01, 0.05, and 0.1 mg/kg in accordance with the EU requirements. The obtained results were acceptable as far as validation criteria are concerned, given recoveries between 71% and 87% and RSDs between 5% and 24%. The limit of determination for naphthalene was set at 0.005 mg/kg based on the lowest concentration level being validated with acceptable accuracy. The analytical technique was successfully applied to 75 olive oil samples collected from oil mills in Greece and no positive results of naphthalene were detected.