Reagents for determinations of trace impurities in water—phase II

Determinations of trace impurities, pollutants, in water are often complicated by a large number of factors which consume a great deal of time. Thus, ideal reagents--sensitive, specific, stable, water-soluble reagents--are needed for rapid, spectrophotometric determinations of trace impurities in water. A new method for the determination of nitrate in water is described which uses zinc 1-naphthol-4-sulfonate, an easily prepared, readily purified, stable, water-soluble reagent; the reagent is much better than 1-naphthol-4-sulfonic acid, for the determination of nitrate proposed earlier by another worker and subsequently found in this laboratory to be satisfactory only under very carefully controlled conditions. The same reagent, zinc 1-naphthol-4-sulfonate, also has been proposed for the rapid, specific, sensitive determination of nitrite in natural waters. Nitrite readily can be determined at ppm levels in the presence of several thousand fold excess of nitrate. Full development of water resources, and the control of pollutants returned to natural-water systems, are dependent upon methods of determining trace constituents; significant contributions toward meeting those needs have been accomplished in this work. The methods can readily be applied to such diverse systems as lakes where agricultural fertilizer run-off may be significant, to effluents from plants in the food-preparation industry, and to natural-water systems in highly mineralized areas. Effective new research areas are readily identified as an extension of the work reported here, particularly the study of systems which contain ppm-levels of nitrite in the presence of significant concentrations of nitrate.U.S. Department of the InteriorU.S. Geological SurveyOpe