Fariborz Azizinezhad, Arash Borzou and Majid Abdouss
Due to the high consumption of lettuce, the examination of its heavy metals content, including Chromium and Nickel is of enormous importance. This study was conducted in 2012-2013, in which 11 important areas under the cultivation of lettuce in Varamin-Pishva located in Tehran were investigated. To do so, at the time of harvest, three samples were randomly taken from each field and then their fresh and dry weights were measured. The dried samples were dissolved in acid by wet digestion method and the concentrations of Chromium and Nickel in the resulted extract were determined by atomic absorption spectrometry (AAS). The mean content of Chromium in spring cultivated lettuce was 0.3493mg/L and 0.9375 of fresh weight and 17.4636 mg/kg of dry weight, while Chromium content in winter cultivated lettuce was 0.3154 mg/L and 0.8917 of fresh weight and 15.7682 mg/kg of dry weight. The concentration of Nickel was less than of 5 mg/kg and 0.4 mg/kg in dry and fresh weight, respectively. The results demonstrated that the lettuce cultivated in these areas is free from Chromium and Nickel contamination for humans.
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