Analytica Chimica Acta 636 (2009) 198–204 Contents lists available at ScienceDirect Analytica Chimica Acta journal homepage: www.elsevier.com/locate/aca Peat as a natural solid-phase for copper preconcentration and determination in a multicommuted ﬂow system coupled to ﬂame atomic absorption spectrometry A.P.S. Gonzáles a , M.A. Firmino b , C.S. Nomura a , F.R.P. Rocha c , P.V. Oliveira c , I. Gaubeur a,∗ a Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia, 166, 09210-170 Santo André, Brazil b Departamento de Engenharia de Materiais, Escola de Engenharia, Universidade Presbiteriana Mackenzie, Rua da Consolac ¸ão, 930, 01302-970 São Paulo, Brazil c Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000 São Paulo, Brazil article info Article history: Received 24 September 2008 Received in revised form 20 January 2009 Accepted 22 January 2009 Available online 1 February 2009 Keywords: Peat Preconcentration Flow analysis Multicommutation Copper abstract The physical and chemical characteristics of peat were assessed through measurement of pH, percentage of organic matter, cationic exchange capacity (CEC), elemental analysis, infrared spectroscopy and quanti- tative analysis of metals by ICP OES. Despite the material showed to be very acid in view of the percentage of organic matter, its CEC was signiﬁcant, showing potential for retention of metal ions. This character- istic was exploited by coupling a peat mini-column to a ﬂow system based on the multicommutation approach for the in-line copper concentration prior to ﬂame atomic absorption spectrometric determi- nation. Cu(II) ions were adsorbed at pH 4.5 and eluted with 0.50 mol L -1 HNO 3 . The inﬂuence of chemical and hydrodynamic parameters, such as sample pH, buffer concentration, eluent type and concentration, sample ﬂow-rate and preconcentration time were investigated. Under the optimized conditions, a linear response was observed between 16 and 100 gL -1 , with a detection limit estimated as 3 gL -1 at the 99.7% conﬁdence level and an enrichment factor of 16. The relative standard deviation was estimated as 3.3% (n =20). The mini-column was used for at least 100 sampling cycles without signiﬁcant variation in the analytical response. Recoveries from copper spiked to lake water or groundwater as well as concen- trates used in hemodialysis were in the 97.3–111% range. The results obtained for copper determination in these samples agreed with those achieved by graphite furnace atomic absorption spectrometry (GFAAS) at the 95% conﬁdence level. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Spectrometric techniques are widely applied for trace metals quantiﬁcation in environmental (water, soil, sediment and par- ticulate material), biological and foodstuff samples. Flame atomic absorption spectrometry (FAAS) is the most largely used analyti- cal method in this group due to its low cost, friendly operation, high sample throughput and good selectivity. However, there are some drawbacks that lessen sensitivity of the technique, including low sample introduction efﬁciency and low residence time of the atoms in ﬂame [1,2]. Electrothermal atomic absorption spectrometry (ETAAS) is more sensitive than FAAS due to higher residence time of the atomic cloud in the optical path as well as the higher efﬁciency of sam- ple introduction. However, ETAAS presents higher acquisition and operational costs, being the analytical determinations also more time consuming. Inductively coupled plasma optical emission spectrometry (ICP OES) allows sequential or simultaneous quantiﬁ- ∗ Corresponding author. Tel.: +55 11 4496 0044. E-mail address: ivanise.gaubeur@ufabc.edu.br (I. Gaubeur). cation of several elements, while inductively coupled plasma mass spectrometry (ICP-MS) is also simultaneous and more sensitive [2]. Despite the higher sensitivity of ETAAS and ICP-MS, these tech- niques hold limitations related to interferences in the formation of the atomic cloud in ETAAS and the possibility of salt deposition in the equipment interface for ICP-MS [2,3]. In spite of the recent advances in instrumentation and improve- ments in selectivity and sensitivity, there is still a need for preconcentration and separation of trace elements prior to their analyses owing to achieve low detection limits and removal of potential interfering matrix constituents [3–6]. Several strate- gies can be used for separation and preconcentration, such as liquid–liquid, solid–liquid and cloud point extraction [6–10], as well as classical alternatives, such as precipitation and coprecipitation [4,5]. In comparison to the other strategies, solid–liquid extrac- tion provides simplicity, lower sample contamination risks and higher enrichment factors, in addition to easier coupling to ﬂow systems, improving sampling throughput and minimizing sample and reagents consumption [11–15]. A number of materials have been used for solid–liquid extraction [16], such as polyurethane foam [3], polymeric resins [11], modiﬁed silica gel [17] and active carbon [18]. Some biological materials and 0003-2670/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.aca.2009.01.047