Nitrate and nitrite accumulation in tomato and potato in Ardabil province

The research was conducted to determine the residual nitrite and nitrate on potatoes and tomatoes, two commercially important vegetables in Ardabil province. Samples of these plants were collected randomly from farms and wholesale markets in 10 day intervals at harvesting time in three sites (Ardabil, Parsabad and Meshkin Shahr) during 2004 and 2005. The samples were analyzed for residual nitrate and nitrite using spectroscopic method. The results revealed that in 10% of potato samples nitrate concentration was more than acceptable level (465 – 519.3 mg/kg fresh weight). Nitrite residue in potatoes ranged from 0.1 to 1.12 mg/kg. The nitrite and nitrate concentrations of 83.4% and 33% of tomato samples were lower than detecting limit of the methods. The amount of nitrate in tomato samples of Meshghin shahr was 20 fold lowers than Parsabads region that probably resulted from higher nitrogen fertilizers application in this region