tAn ion chromatography (IC) method was developed for the simultaneous determination of total nitrogenand total phosphorus after alkaline persulfate digestion. This study takes advantage of advances in con-struction of high-resolution, high-capacity anion-exchange columns that can better tolerate the matricestypically encountered when a determination of total nitrogen and total phosphorous is required. Here, weused an electrolytically generated hydroxide eluent combined with a high-capacity, hydroxide-selective,anion-exchange column for the determination of total nitrogen (as nitrate-N) and total phosphorus (asphosphate-P) in environmental samples by IC. This method yielded LODs for nitrate-N and phosphate-P of1.0 and 1.3 g/L, respectively. The LOQs determined for these analytes were 3.4 and 4.2 g/L, respectively.Due to the dilution factor required and the blank nitrate-N concentration after the persulfate digestion,the quantification limits increased for nitrate-N and phosphate-P to 171 and 63 g/L, respectively. Thesuitability of the method was evaluated by determining the nitrogen and phosphorus concentrations fromknown concentrations of organic-containing nitrogen and phosphorus compounds. In addition, environ-mental samples consisting of six different wastewaters and 48 reservoir samples were evaluated fortotal nitrogen and phosphorus. The recoveries of nitrogen and phosphorus from the organic-containingcompounds ranged from 93.1 to 100.1% and 85.2 to 97.1%, respectively. In addition, good correlationbetween results obtained by the colorimetric method and IC was also observed. The linearity, accuracy,and evaluation of potential interferences for determining TN and TP will be discussed