Flow Injection Determination of Nitrate in Vegetables Using a Tubular Potentiometric Detector

• Published in: Journal of agricultural and food chemistry Vol. 43; no. 3; pp. 704 - 707
• Main Authors: Lima, Jose L. F. C, Rangel, Antonio O. S. S, Souto, M. Renata S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-03-1995
• Subjects: ALIMENTOS; ANALYTICAL METHODS; Biological and medical sciences; CHEMICAL COMPOSITION; COMPOSICION APROXIMADA; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; COMPOSITION GLOBALE; DRIED PRODUCTS; FLOW INJECTION ANALYSIS; FOOD COMPOSITION; Food industries; FOODS; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; HORTALIZAS; LEGUME; NITRATE; NITRATES; NITRATOS; POTENCIOMETRIA; POTENTIOMETRIE; POTENTIOMETRY; PRODUCTOS SECOS; PRODUIT ALIMENTAIRE; PRODUIT SECHE; PROXIMATE COMPOSITION; TECHNIQUE ANALYTIQUE; TECNICAS ANALITICAS; TITRIMETRIA; TITRIMETRIE; TITRIMETRY; VEGETABLES; Analytical method; Nitrates; Potentiometry; Nitrogen fertilizer; Vegetable; Quantitative analysis; Chemical contamination; Flow injection
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf00051a027

A flow injection system with potentiometric detection for the determination of nitrate in vegetables was developed. For this purpose a tubular nitrate ion-selective electrode with the ion-exchanger system [(4,7-diphenylphenanthroline)nickel(II) dissolved in o-nitrophenyl octyl ether] immobilized in a PVC membrane and without inner reference solution was prepared. The flow injection manifold incorporating the tubular electrode was used for the determination of nitrate in vegetables (lettuce, parsley, and spinach), using a mixture of lead acetate, lead oxide, and sodium acetate as nitrate extractant, ionic strength adjustor, and interference suppressor solution. The quality of the results obtained by the proposed methodology was assessed by comparing them with those provided by a conventional potentiometric methodology and also through recovery tests (recoveries from 94 to 104% were found). A sampling rate of 120 samples per hour was achieved with a relative standards deviation lower than 2%