A rapid, microwave-based extraction method was employed to oxidize all forms of nitrogen to nitrate in environmental samples using persulfate. The digest was then analyzed spectrophotometrically after an offline reduction of nitrate to nitrite using a cadmium reductor column was completed. The precision of the method was tested at the 0.5 mg l-1 level and was 5.2% (N = 10). The detection limit based on S/N = 3 was calculated to be 0.15 mg l-1. The method was thoroughly validated by comparison of analytical techniques and intralaboratory comparison studies.