title: Development of a new sequential injection in-line cloud point extraction system for flame atomic absorption spectrometric determination of manganese in food samples.
abstract: A preconcentration method for manganese determination by sequential injection cloud point extraction with subsequent detection by flame atomic absorption spectrometry (FAAS) has been developed. The enrichment of Mn was performed after a preliminary on-line cloud point extraction and entrapment of manganese-containing surfactant aggregated within a minicolumn packed with cotton. The laboratory-made reagent 4-(5'-bromo-2'-thiazolylazo)orcinol (Br-TAO) and the surfactant Triton X-114 were used for cloud point extraction. The manganese ions were eluted with sulphuric acid solution and directly introduced into the FAAS. Chemical and flow variables affecting the preconcentration were studied. Using a sample volume of 2.80 mL the limit of detection and enrichment factor were calculated to be 0.5 microg L(-1) and 14, respectively. The sample frequency is 48 h(-1), considering a total run cycle of 75 s. The accuracy of the proposed method has been demonstrated by the analysis of the certified reference biological materials rice flour and tomato leaves. The method has been applied to determination of manganese in food samples.
authors.affiliation: Universidade Estadual do Sudoeste da Bahia, Núcleo de Química Analítica da Bahia, Laboratório de Química Analítica, Campus de Jequié, 45.506-191 Jequié, Bahia, Brazil. valfredoazevedo@yahoo.com.br
authors.forename: Valfredo Azevedo
authors.initials: VA
authors.lastname: Lemos
authors.forename: Patrícia Xavier
authors.initials: PX
authors.lastname: Baliza
authors.forename: Anaildes Lago
authors.initials: AL
authors.lastname: de Carvalho
authors.forename: Rafael Vasconcelos
authors.initials: RV
authors.lastname: Oliveira
authors.forename: Leonardo Sena Gomes
authors.initials: LS
authors.lastname: Teixeira
authors.forename: Marcos Almeida
authors.initials: MA
authors.lastname: Bezerra
mesh_terms: D005504:Food Analysis / Q000295:instrumentation* / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D008345:Manganese / Q000032:analysis*; D015394:Molecular Structure; D013054:Spectrophotometry, Atomic / Q000295:instrumentation* / Q000379:methods*
chemical_list: D007477:Ions; D008345:Manganese