Sensitive determination of nitrite by means of a Landolt-type reaction in fluorescent aggregates of a binaphthyl-based amphiphile

Abstract

Abstract.The iodine quenching effect on the fluorescence of a binaphthyl-based amphiphile, CsBNC6 N, was used for monitoring the LandoR-type reaction between nitrite, iodide, and thiosulfate. Due to the possibility of iodine detection in the 10-s-10-7 M range, and to the effective concentration of anionic reagents on the surface of cationic aggregates, the indicator reaction can be monitored using reagents at concentration levels as low as 10-TM. To optimize the analytical system, the effect of pH and reagent concentrations on the rate of indicator reaction were studied. The influence of the matrix of water samples and effect of side-reactions increasing the value of a blank test were examined. A procedure for nitrite determination in water was developed, using the diazo reaction for selective nitrite removal to provide a reference solution, which avoided possible effects of the matrix components. The usefulness of this method was tested by determining trace amounts of nitrite in water samples. The procedure allows determination of nitrite down to 5 ng/ml (detection limit about 2 ng/ml) with r.s.d, of 10% in the 20-250 ng/ml range.Key words: binaphthyl-based amphiphile, fluorimetry, nitrite, Landolt reaction.Nitrogen-containing inorganic compounds, including nitrite, have a strong toxic effect on living organisms. There is a need, therefore, to determine extremely low nitrite levels in food and drinking water samples. Nitrites are most often determined by spectrophotometric methods involving azo dye formation [1, 2-1, as well as by electrochemical [3], chromatographic" [4, 5-], and spectrofluorimetric [6, 7-1 methods. A classical approach of nitrite determination is also known, in which the oxidation of iodide by nitrite in acidic medium is employed [-8-1. 2NO2 + 3I-+ 4H + --~ 2NO + I~-+ 2HaO(1)

The construction of a simple sensor for the simultaneous detection of nitrite and thiosulfate by heme catalysis

“…Because its appearance is similar to that of salt, some lawbreakers will use NO 2 À to make fake salt. 5,6 Sodium thiosulfate (Na 2 S 2 O 3 ) can be produced by thiosulfate (S 2 O 3 2À ) and sodium metal. S 2 O 3 2À can also be used for applications in medical treatment, such as the detoxication of cyanide.…”