Photo-Fenton approach for the determination of organic nitrogen in rainwater

Autor(es)

Crispim, Cristina P. ^[1] ; Nogueira, Raquel F. P. ^[2] ; Ometto, Jean P. ^[3] ; Campos, M. Lucia A. M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Quim, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] Univ Estadual Paulista UNESP, Dept Quim Analit, Inst Quim, BR-14800060 Araraquara, SP - Brazil

^[3] Natl Inst Space Res, Earth Syst Sci Ctr, BR-12227010 Sao Jose Dos Campos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Atmospheric Environment; v. 191, p. 525-531, OCT 2018.
• Citações Web of Science: 0

Resumo

The importance of taking the organic forms of nitrogen (ON) into account when estimating atmospheric nitrogen deposition has been known for a long time. However, there is still only a modest amount of data on organic nitrogen in rainwater worldwide, largely due to the difficulties and uncertainties imposed by the available analytical methods. This work offers a simple, low cost, and reliable method for the determination of ON in rainwater, based on the photo-Fenton process under UV irradiation. The recovery of ON was determined using individual solutions of urea, serine, glycine, and histidine, as well as a mixture of all these compounds plus arginine. Close to 100% organic nitrogen recoveries were obtained for solutions containing 50 mol N L-1, using addition of 50 molL(-1) Fe2+ and 2.0 mmol L-1 H2O2, with adjustment of the pH to similar to 2.5 and irradiation for 90 min. The average reagent blank was < 2.0 mol N L-1. The homemade reactor employed a 400 W high pressure mercury lamp, from which the external bulb had been manually removed. The reactor ventilation was controlled in order to maintain the temperature at - 85 degrees C. The precision of the method ranged from 1.3 to 5.7%, based on ON recovery. Rainwater collected on an event basis in Ribeirao Preto (Sao Paulo State, Brazil) presented ON concentrations from 4.1 to 34.3 nmol L-1 (n = 18), corresponding to 13-45% of the total nitrogen, with an average contribution of 33%. Precision of s <= 7.0% was obtained for the analysis of ON in rainwater. (AU)

• Processo FAPESP: 13/12789-8 - Investigando o comportamento de espécies orgânicas e inorgânicas na água de chuva de Ribeirão Preto: uma cidade com elevada atividade canavieira em franco processo de modificação
• Beneficiário: Maria Lúcia Arruda de Moura Campos
• Modalidade de apoio: Auxílio à Pesquisa - Regular