Proposed Method for Nitrate in Potable Waters

This article presents a new method for measuring the nitrate ion content of potable water. The method is based on the absorption of nitrate ion at 210 mμ, measured against a duplicate sample (blank) in which the nitrate ion has been reduced to ammonia by a zinc‐copper couple. The use of a blank thus prepared permits the canceling out of all interfering substances except nitrite. As nitrite ion content of potable waters has been shown to be extremely low, interference from nitrite ion is not a factor. Waters having a nitrate ion content in excess of 8.8 mg/l must be diluted in order to use the proposed method. This dilution aids in reducing any nitrite ion interference which may be present.