[Content of nitrates and nitrites in market vegetables in Wroclaw in the years 1996-1997]

The aim of analytical investigation included in this paper was the determination the nitrate and nitrite contents in 8 common vegetables: cabbage, carrot, parsley, potato, garden beet, cucumber, lettuce and radish in relation to the acceptable levels of nitrates. The samples of vegetables were taken from detail shops in Wrocław in the years 1996-1997. A total of 151 samples of vegetables were analyzed. The nitrate and nitrite level was determined collorimetricaly with sulfanilic acid after previous reduction of nitrates to nitrites by means of cadmium column. The acceptable values of nitrates were exceeded in 82% of the samples of radish and in 65% samples of lettuce. The smallest amount of samples with excess of the acceptable nitrate levels were found in potato, carrot and cucumber. It was found, that the nitrate content in the greenhouse vegetables: lettuce, cucumber and radish was greater than in the field vegetables. The potato, cabbage and carrot investigated after winter storage comprised lower content of nitrates than in freshly harvested. Nitrite accumulation in investigated vegetables was low, but the highest concentrations were found in lettuce and radish form greenhouse.