DAN is a highly selective colorimetric and fluorometric reagent for Se detection. This reagent is almost insoluble in cold water and alcohol, but it is higly soluble in water at 50ºC. DAN forms 4,5-benzopiaselenol by the complex with Se, and this complex is extracted with chloroform, toluene, or cyclohexane. Since the Se complex is volatile, Se can be determined by gas chromatography. Further, DAN generates fluorescent naphthalenetriazole by the reaction with nitrite ion, so it is also used for the fluorometric determination of nitrite.
Solvent extraction, colorimetric: Se(IV) (in toluene at pH 1.2-2.2, λmax=380 nm, ε=11,800, detection range 0-4 ppm)
Solvent extraction, fluorometric: Se(IV) (λem=520 nm in toluene, λem=538 nm in cyclohexane, detection range 1-100 ppb)
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