Development of a spectrophotometric Sequential Injection Analysis (SIA) procedure for determination of ammonium: A Response Surface Methodology (RSM) approach

Autor(es)

Infante, Carlos M. C. ^[1] ; Masini, Jorge C. ^[1] ; dos Santos, Allan C. V. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim, BR-05513970 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Microchemical Journal; v. 98, n. 1, p. 97-102, MAY 2011.
• Citações Web of Science: 5

Resumo

This paper describes the optimization and use of a Sequential Injection Analysis (SIA) procedure for ammonium determination in waters. Response Surface Methodology (RSM) was used as a tool for optimization of a procedure based on the modified Berthelot reaction. The SIA system was designed to (i) prepare the reaction media by injecting an air-segmented zone containing the reagents in a mixing chamber, (ii) to aspirate the mixture back to the holding coil after homogenization, (iii) drive it to a thermostated reaction coil, where the flow is stopped for a previously established time, and (iv) to pump the mixture toward the detector flow cell for the spectrophotometric measurements. Using a 100 mu mol L(-1) ammonium solution, the following factors were considered for optimization: reaction temperature (25 - 45 degrees C), reaction time (30 - 90 s), hypochlorite concentration (20 - 40 mmol L(-1)) nitroprusside concentration (10 - 40 mmol L(-1)) and salicylate concentration (0.1 - 0.3 mol L(-1)). The proposed system fed the statistical program with absorbance data for fast construction of response surface plots. After optimization of the method, figures of merit were evaluated, as well as the ammonium concentration in some water samples. No evidence of statistical difference was observed in the results obtained by the proposed method in comparison to those obtained by a reference method based on the phenol reaction. (C) 2010 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 08/09284-3 - Desenvolvimento de metodologias para determinação de substâncias orgânicas utilizando Análise por Injeção Seqüencial (SIA) e cromatografia a líquido de alta eficiência em colunas monolíticas
• Beneficiário: Carlos Martín Infante Córdova
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado