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Indirect determination of N-total in plant materials by flame atomic absorption spectrometry involving a AgCl(s) mini-column

A flow-injection system with a AgCl(s) mini-column is proposed for the determination of total nitrogen in plant digests by flame atomic absorption spectrometry. The method is based on Ag+ removal by ammonia through the formation of the diammine argentate(I) complex and further monitoring of the released Ag+. Nitrogen was determined in seven reference samples, in three replicates, with precision and accuracy comparable to the conductimetric procedure. The system is robust, and only slight sensitivity variations (< 2 %) have been noted during extended (4 h) operating periods. Sampling rate is about 100 h-1 and measurement repeatability is fair (relative standard deviation usually < 0.02).

N-total; flow-injection analysis; atomic absorption spectrometry; mini-column

Escola Superior de Agricultura "Luiz de Queiroz" USP/ESALQ - Scientia Agricola, Av. Pádua Dias, 11, 13418-900 Piracicaba SP Brazil, Phone: +55 19 3429-4401 / 3429-4486 - Piracicaba - SP - Brazil