Formation of N-nitroso compounds of the pesticides atrazine, simazine and carbaryl with nitrogen oxides.

The nitrosation of atrazine, simazine and carbaryl by nitrogen oxides was investigated in model experiments. Pure pesticides and their corresponding formulations were exposed, as dry powders and as aqueous suspensions, to defined concentrations of NOx (1000, 100, 10 and 1 ppm) in a reaction chamber. Nitrosated pesticides were determined by HPLC-TEA. Generally, the amount of nitrosation increased with the reaction time. At high NOx concentrations (1000 and 100 ppm), nitrosation approached saturation. For atrazine and simazine, further reaction with nitrogen oxides might occur. Nitrosation rates of dry powdered pesticides were inversely proportional to grain size and to air moisture content. Nitrosation of aqueous pesticide suspensions by nitrogen oxides was strongly inhibited at pH values higher than 5.