Catalytic spectrophotometric determination of trace nitrite in water samples with 3,5-diBr-PADAT

In a H3PO4 medium,a new catalytic spectrophotometric method for the determination of trace amount of nitrite was established using 3,5-diBr-PADAT.This method was based on the catalytic effect of nitrite on the oxidation reaction of 3,5-diBr-PADAT by KBrO3.Experimental results showed that the absorbance at 434 nm was proportional to the nitrite concentration.The detection limit for nitrite was 4.56×10-7mol/L.The linear range of the determination was 10-7～10-5mol/L.The method has been successfully applied to the determination of nitrite in samples of lake water,tap water and mineral water,and the analytical results were satisfactory.