“…More recently, chromatographic techniques using sophisticated and costly instrumentation, such as ion chromatography (IC), LC, and GC/MS, have found application in environmental NO 3 monitoring studies and biomedical research (1,4). Other commonly used techniques for direct NO 3 measurement include colorimetric determination using reaction with chromotropic acid (CTA; 5), potentiometric analysis using nitrate-specific electrodes (6), and quantification by UV absorbance spectrometry (7,8). Unfortunately, many of these techniques are severely compromised by common sample matrix components, such as excess salt, phosphate, colored pigments, soluble proteins, enzymes, humic substances, etc., precluding their use unless expensive and time-consuming cleanup procedures are used.…”