This method quantitatively measures soluble nitrate (NO3-N) in botanical materials based on an extraction with a solution of 2% acetic acid. Nitrate is determined by Flow Injection Analysis (FIA) using the reduction to nitrite via a copperized cadmium column, diazotization with sulfanilamide followed by coupling with N-(1-naphthyl)ethlyenediaminie dihydrochloride. The absorbance of the product is measured at 520 nm.
Nitrate concentration is used to assess plant overall nitrogen status and is correlated to plant response to nitrogen fertilization. The method has a quantitative detection limit of 10 ppm (dry basis).
Sample amount requested: 3 g
Questions concerning limited sample size can be answered by the UC Davis Analytical Laboratory.
Miller, R. O. 1998. Extractable Chloride, Nitrate, Orthophosphate, and Sulfate-Sulfur in Plant Tissue: 2% Acetic Acid Extraction, in Handbook of Reference Methods for Plant Analysis, Chapter 15, pp. 115-118.
Sechtig, A. 1992. Determination of Nitrate/Nitrite by Flow Injection Analysis in 2 M KCl soil extracts. QuikChem Method 12-107-04-1-B. Lachat Instruments, Milwaukee, WI.
