Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10556920 | Microchemical Journal | 2011 | 6 Pages |
Abstract
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 μmol Lâ 1 ammonium solution, the following factors were considered for optimization: reaction temperature (25 - 45 °C), reaction time (30 - 90 s), hypochlorite concentration (20 - 40 mmol Lâ 1), nitroprusside concentration (10 - 40 mmol Lâ 1) and salicylate concentration (0.1 - 0.3 mol Lâ 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.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Carlos M.C. Infante, Jorge C. Masini, Allan C.V. dos Santos,