Spectrophotometric determination of total nitrogen in

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An improved flow-injection system with an AgCl(s) reactor is proposed for the ... Keywords: Flow analysis; Total nitrogen; Plant material; Spectrophotometry; ...
Analytica Chimica Acta 416 (2000) 185–190

Spectrophotometric determination of total nitrogen in plant materials using a flow-injection system with an AgCl(s) reactor Josiane M.T. Carneiro, Raquel P. Sartini, Elias A.G. Zagatto∗ Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, P.O. Box 96, 13400-970 Piracicaba SP, Brazil Received 11 October 1999; received in revised form 28 March 2000; accepted 29 March 2000

Abstract An improved flow-injection system with an AgCl(s) reactor is proposed for the spectrophotometric determination of total nitrogen in Kjeldahl digests of plant materials. After sample injection, the established sample plug is alkalinised and allowed to flow through the mini-column where Ag+ ions are displaced as the soluble [Ag(NH3 )2 ]+ complex. Bromopyrogallol red and o-phenanthroline are then added and a coloured ternary complex is formed under neutral conditions. The system is very stable, and baseline drift is usually 5%) were noted when these reagents were added through separate confluence sites. Therefore, for seeking simplicity in system design, it was decided to add both reagents in the same bottle. No analytical signal was detected for [BPR]