Effect of surfactants on the determination of nitrite and nitrate in water samples

Summary The effect of four surfactants on the determination of nitrite and nitrate has been examined. The method which has been tested for nitrite is based on the formation of an azodye. The results show that cationic and non-ionic surfactants do not interfere with the determination of nitrite while anionic surfactants cause significant interferences, which could be eliminated by treating the water samples with a cationic surfactant.Two methods have been tested for the determination of nitrate in the presence of surfactants. One method is based on the nitration of salicyclic acid, while the other is based on the reduction of nitrate to nitrite. Results for the first method show that the non-ionic surfactant Triton-X causes significant interferences. Cationic and anionic surfactants do not interfere, when their concentration is relatively low. For higher concentrations an increasing interference is observed. Results for the second method show effects similar to those obtained for nitrite.

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Wirkung oberflächenaktiver Substanzen auf die Bestimmung von Nitrit und Nitrat in Wasserproben