Rapid Determination of Very Low Nitrogen Levels in Water

THE importance of nitrogen in the various life cycles of interacting ecosystems has been well described 1–4 . The pertinent concentration levels may be as low as 5 × 10 −9 g kg −1 in water 3 . Quick, accurate and nondestructive tests for the presence of these levels of nitrogen are of practical importance. We report here a new approach to 14 N assay, associated with the evaporated detritus of less than 4 ml. of water. The present overall accuracy is about ±25% at concentrations greater than 200 × 10 −9 g kg −1 ; the test is sensitive down to levels of about 20 × 10 −9 g kg −1 . These figures can be improved by relatively simple procedures. The testing time per sample is about 3 min and the sample is not destroyed by the test.