title: Determination of low-molecular-weight amines and ammonium in saline waters by ion chromatography after their extraction by steam distillation.
abstract: A new method was developed for the determination of ammonium ion, monomethylamine and monoethylamine in saline waters by ion chromatography. Steam distillation was used to eliminate matrix interferences. Variables such as distillation time, concentration of sodium hydroxide solution and analyte mass were optimized by using a full two-level factorial (2(3) ) design. The influence of steam distillation on the analytical curves prepared in different matrices was also investigated. Limits of detection of 0.03, 0.05 and 0.05 mg/L were obtained for ammoniumion, monomethylamine and monoethylamine, respectively. Saline water samples from the Brazilian oil industry, containing sodium and potassium concentrations between 2.0-5.2% w/v and 96-928 mg/L, respectively, were analyzed. Satisfactory recoveries (90-105%) of the analytes were obtained for all spiked samples, and the precision was ≤ 7% (n = 3). The proposed method is adequate for analyzing saline waters containing sodium to ammoniumion, monomethylamine and monoethylamine concentration ratios up to 28 000:1 and potassium to ammonium, monomethylamine and monoethylamine concentration ratios up to 12 000:1.
authors.affiliation: Departamento de Química Analítica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.|Coordenação de Análises Minerais, Centro de Tecnologia Mineral-CETEM, Rio de Janeiro, Brazil.
authors.forename: Fernanda Nunes
authors.initials: FN
authors.lastname: Ferreira
authors.affiliation: Departamento de Química Analítica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Julio Carlos
authors.initials: JC
authors.lastname: Afonso
authors.affiliation: Departamento de Química Analítica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Fernanda Veronesi Marinho
authors.initials: FV
authors.lastname: Pontes
authors.affiliation: Coordenação de Análises Minerais, Centro de Tecnologia Mineral-CETEM, Rio de Janeiro, Brazil.
authors.forename: Manuel Castro
authors.initials: MC
authors.lastname: Carneiro
authors.affiliation: Coordenação de Análises Minerais, Centro de Tecnologia Mineral-CETEM, Rio de Janeiro, Brazil.
authors.forename: Arnaldo Alcover
authors.initials: AA
authors.lastname: Neto
authors.affiliation: Petrobras/CENPES, Cidade Universitária, Rio de Janeiro, Brasil.
authors.forename: Maria Luiza Bragança
authors.initials: ML
authors.lastname: Tristão
authors.affiliation: Coordenação de Análises Minerais, Centro de Tecnologia Mineral-CETEM, Rio de Janeiro, Brazil.
authors.forename: Maria Inês Couto
authors.initials: MI
authors.lastname: Monteiro
keywords: Ammonium; Ion chromatography; Monoethylamine; Monomethylamine; Saline water