Oliveira, Sara M.Lopes, Teresa I. M. S.Rangel, António O. S. S.2011-10-222011-10-222007"Communications in soil science and plant analysis". ISSN 0010-3624. 38: 3-4 (2007) 533-544http://hdl.handle.net/10400.14/6765A sequential injection system for the determination of nitrate (NO3 2) in vegetables was developed to automate this determination, allowing for substantially reduced reagent consumption and generated waste using low-cost equipment. After extraction with water and filtration, the extracted nitrate is reduced inline to nitrite in a copperized cadmium (Cd) column and determined as nitrite. According to the Griess–Ilosvay reaction, nitrate is diazotized with sulfanilamide and coupled with N-(1-naphtyl)-ethylenediamine dihydrochloride to form a purple-red azo dye monitored at 538 nm. Nitrate can be determined within a range of 1.35–50.0 mg L21 of NO3 2 (corresponding to 0.270–10.0 g of NO3 2 per kg of vegetable), with a conversion rate of nitrate to nitrite of 99.1+0.8%. The results obtained for 15 vegetable extracts compare well with those provided by the classical procedure, with a sampling throughput of 24 determinations per hour and relative standard deviations better than 1.2%.engCopperized cadmium columnNitrateSequential injection analysisSpectrophotometryVegetablesjournal article10.1080/00103620601174635