DETERMINATION OF SUBNANOMOLAR CONCENTRATIONS OF NITRITE IN NATURAL-WATERS

Dissolved nitrite in natural waters was determined at subnanomolar lev els by derivitization with 2,4-dinitrophenylhydrazine (2,4-DNPH) follo wed by liquid chromatography. The analysis is rapid, involves minimal sample preparation, and requires fairly standard laboratory equipment. The method has undetectable blanks and a detection limit of 0.1 nM wi th an average precision of 4% RSD at ambient natural water concentrati ons, The azide formed upon reaction of NO2- with 2,4-DNPH at levels ty pically found in coastal seawater is stable for at least 4 weeks when kept cold in the dark, The stability of the nitrite derivative is extr emely useful because it allows for large numbers of samples to be coll ected and derivatized in relatively short time periods for later chrom atographic analysis. Analytical results were verified by intercomparis on with a standard, completely independent, colorometric technique in several natural water types, Applications to fresh, estuarine, and mar ine samples are also presented.