title: Use of factorial design and Doehlert matrix for multivariate optimisation of an on-line preconcentration system for lead determination by flame atomic absorption spectrometry.
abstract: A system for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS) was proposed. It was based on the sorption of lead(II) ions on a minicolumn of polyurethane foam loaded with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM). The optimisation step was carried out using two-level full factorial and Doehlert designs for the determination of the optimum conditions for lead preconcentration. The proposed procedure allowed the determination of lead with a detection limit of 2.2 microg L(-1), and a precision, calculated as relative standard deviation (RSD), of 2.4 and 6.8 for a lead concentration of 50.0 and 10.0 microg L(-1), respectively. A preconcentration factor of 45 and a sampling frequency of 27 samples per hour were obtained. The recovery achieved for lead determination in the presence of several cations demonstrated that this procedure has enough selectivity for analysis of environmental samples. The validation was carried out by analysis of certified reference material. This procedure was applied to lead determination in natural food.
authors.affiliation: Instituto de Química, Grupo de Pesquisa em Química Analítica, Campus Universitário de Ondina, Universidade Federal da Bahia, 40170-290 Salvador, Brasil. slcf@ufba.br
authors.forename: S L C
authors.initials: SL
authors.lastname: Ferreira
authors.forename: W N L
authors.initials: WN
authors.lastname: dos Santos
authors.forename: M A
authors.initials: MA
authors.lastname: Bezerra
authors.forename: V A
authors.initials: VA
authors.lastname: Lemos
authors.forename: J M
authors.initials: JM
authors.lastname: Bosque-Sendra
mesh_terms: D002412:Cations; D002845:Chromatography; D004867:Equipment Design; D005504:Food Analysis; D007854:Lead / Q000032:analysis*; D009862:Online Systems; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013054:Spectrophotometry, Atomic / Q000295:instrumentation / Q000379:methods* / Q000592:standards
chemical_list: D002412:Cations; D007854:Lead