Methods of Analysis by the U.S. Geological Survey National Water Quality Laboratory: Evaluation of Alkaline Persulfate Digestion as an Alternative to Kjeldahl Digestion for Determination of Total and Dissolved Nitrogen and Phosphorus in Water;Water-resou

摘要

This report describes USGS methods I-2650-03 and I-4650-03 for determining total nitrogen and total phosphorus in filtered and whole-water alkaline persulfate digests, respectively. All aspects of the methods are described, including sample preparation and digestion, colorimetric determinations of nitrate and orthophosphate in alkaline persulfate digests, calculation of results, bias, precision, and repeatability of results, and conventions for reporting results. These methods supplement other methods of the USGS for determination of inorganic substances in water that are described by Fishman and Friedman (1989) and Fishman (1993).