بررسی مقدار فلزات سمی کادمیوم ، کرم ، سرب و جیوه در رب گوجه فرنگی در شهر اصفهان

          Toxic metals such as Cd, Cr, Pb and Hg, in trace amounts, enter the    human body through food products. One of the main sources is the    corrosion of the metal made apparatus, which are used in the process of    food production. Tomato paste with an average pH value of 4.6 capable of    containing such elements.           The effect of metallic apparatus on the concentration of toxic metals in     tomato paste was evaluated. For this purpose 50 samples of tomato, 25    samples of tomato juices and 61 samples of tomato pastes were collected ,    and digested with nitric acid. Cadmium and chromium were determined,    using atomic absorbtion (AA), lead (Pb) were determined using    diphenylcarbazid and spectrophotometer. Mercury (Hg) was determined    using cold vapor AA. Statistical method , ANOVA and Dunken tests  were    used for data analysis. The percent of recovery of the methods were also    determined.          The results of the study indicated that the recovery of the methods were    over than 93 percent, using the spiked samples of 1 and 5 PPM of the    metals. The results of the study also showed that the concentration of the    Cd, Cr, and Pb were below the standard level in home made tomato paste     samples.  The concentration of  Hg in all samples were below the standard    level and the detection limit of the instrument used. The study also revealed    that absence of Hg in all samples could be because of the lack of this    element in the percent impurity of the apparatus used .           Statistical analysis showed the significant differences between the    methods of preparation of  tomato paste which confirm the role of non-    standard apparatus in increasing the concentration of toxic elements in    tomato paste.