Determination of total nitrogen in food by flow injection analysis (FIA) with a potentiometric differential detection system

• Type: Article in International Scientific Journal
• Date: 1999

Authors

Lima, JLFC (Author) FFUP; Montenegro, MCBSM (Author) FFUP; Pinto, APMMO (Author) Other

Journal

Title: Fresenius' Journal of Analytical Chemistry

Vol. 364

Pages: 353-357

ISSN: 0937-0633

Publisher: Springer

Indexing

ISI Web of Knowledge - 11 Citations

Scopus - 12 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-001-465

DOI: 10.1007/s002160051348

Abstract (EN): A flow injection set-up based on potentiometric detection and gas diffusion device for the determination of total nitrogen in food is described. The detection system consisted of two ammonium-sensitive electrodes placed sequentially and each alternately operating as reference electrode. Tubular electrodes without an inner reference solution were prepared with a PVC membrane composed of nonactin in Tris (2-ethylhexyl) phosphate and potassium tetrakis (4-chlorophenyl) berate to reduce the membrane resistance. The food sample digests were inserted into the system, and the ammonium present was converted into ammonia gas. The gas diffused through a gas-permeable membrane to a buffer acceptor stream with a pH that ensured transformation to the ammonium cation, which was potentiometrically detected. Good agreement between FIA results and those provided by the reference procedure was obtained, with relative deviation errors below 5%. Using the proposed system, low reagent consumption is possible, a sampling rate of about 30 samples/h was achieved, as well as a good reproducibility for consecutive injections of the same sample (variation coefficient < 2%).

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5