Determination of Metal Contents in Edible Vegetable Oils Produced in Iran Using Microwave-assisted Acid Digestion

The concentration of heavy metals in vegetable oils is an important criterion for the assessment of oil qualities with regard to freshness, keeping properties, storage and their influence on human nutrition and health. Trace heavy metals in vegetable oils are known to have an effect on the rate of oil oxidation. In this work, the contents of lead (Pb), cadmium (Cd), nickel (Ni), manganese (Mn), zinc (Zn), copper (Cu), iron (Fe), calcium (Ca) and magnesium (Mg) in four varieties of edible vegetable oils (olive oil, canola oil, sunflower oil and soybean oil) collected from Iran were determined using atomic absorption spectrometry (AAS). The samples were digested in microwave digestion system The concentration of nickel, manganese, zinc, copper, iron, calcium and magnesium were observed in the range of 0.91–2.17, 0.14–1.76, 3.58–9.54, 0.18–0.68, 7.7828.93, 21.42–78.52, 5.34–36.49 μg/g, respectively. Lead and cadmium were found to be 4.56– 15.82 and 1.87–8.58 μg/kg. We found that the content of the heavy metals in all of the tested oils was lower than the maximum values recommended for FAO/WHO .