Simultaneous determination of Cu, Pb, Cd, Ni, Co and Zn in bioethanol fuel by adsorptive stripping voltammetry and multivariate linear regression Danielle S. Nascimento a,1 , Matías Insausti b,2 , Beatriz S.F. Band b,2 , Sherlan G. Lemos a,⇑ a Departamento de Química, Universidade Federal da Paraíba, CP5093, 58051-970 João Pessoa, PB, Brazil b Laboratorio FIA, INQUISUR-CONICET, Departamento de Química, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca, Buenos Aires, Argentina highlights  Simultaneous determination of six trace metals in bioethanol fuel samples.  Multivariate determination of six analytes with a voltammetric method.  MLR aided by variable selection provided excellent quantitative predictions.  Peak alignment and baseline correction are crucial for DPAdSV signal processing. article info Article history: Received 25 June 2014 Received in revised form 28 July 2014 Accepted 31 July 2014 Available online 12 August 2014 Keywords: Ethanol fuel Trace analysis Chemometrics Stripping voltammetry Signal processing abstract In this work it is proposed the one-voltammogram simultaneous determination of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) at ppb and sub-ppb levels in bioethanol fuel samples by adsorptive stripping vol- tammetry. Mixed ligands were employed providing stripping peaks for all analytes at the same voltam- metric scan under optimized conditions. To perform the determination, multivariate linear regression aided by successive projections algorithm (SPA–MLR) was evaluated. The voltammograms were prepro- cessed with the asymmetric least squares (AsLS) baseline correction algorithm and the icoshift peak align- ment tool. An excellent analytical performance was obtained, despite the inherent complexity of the simultaneous determination, with average apparent recovery = 96% ± 16%, and better prediction results in comparison with the benchmark method of partial least squares (PLS). Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction The relevance of biofuels in the global energetic matrix is already established and its quality control becomes crucial. To ensure the quality of biofuels is necessary to establish quality stan- dards, aiming to set limits on levels of contaminants that will not affect the emissions, the engine performance and integrity, as well as the safety in transportation and handling. Ethanol produced on a large scale from sugarcane industries is the biofuel most widely used in Brazil. As automotive fuel, bioeth- anol can be used in its hydrated form, or added in its anhydrous form to type A gasoline to formulate type C gasoline in the propor- tion of 25% [1]. An important control performed for bioethanol is the control of trace metals. The presence of metals in biofuels may occur due to the absorption of metals from the soil by the plant used as raw material, as well as they can be incorporated during the processes of production, storage and transportation [2]. Trace metals in bioethanol can be an indicative of metallic cor- rosion during storage and their presence can accelerate oxidation processes resulting in the formation of gums [3]. Therefore, it is necessary to determine and control the concentration of these impurities in order to reduce the undesirable effects of these contaminants. In general, the analysis of trace metals in ethanol fuel has tradi- tionally been carried out by means of spectroanalytical techniques: flame atomic absorption spectrometry (FAAS) [4,5], electrothermal atomic absorption spectrometry (ETAAS) [6,7] and inductively cou- pled plasma mass spectrometry (ICP–MS) [8]. Electroanalytical techniques such as stripping voltammetry can also be used in the determination of trace metals due to their low detection limits and possibility of simultaneous determinations. In this sense, a http://dx.doi.org/10.1016/j.fuel.2014.07.100 0016-2361/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel./fax: +55 83 32167438. E-mail address: sglemos@pq.cnpq.br (S.G. Lemos). 1 Tel./fax: +55 83 32167438. 2 Tel.: +54 291 4595100; fax: +54 291 4595160. Fuel 137 (2014) 172–178 Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel