In the present study, the performance of multi-walled carbon nanotubes (MWCNTs) grafted with 3-mercaptopropyltrimethoxysilane (3-MPTMS), used as a solid phase extractor for Cd2+ preconcentration in a flow injection system coupled to flame atomic absorption spectrometry (FAAS), was evaluated. The procedure involved the preconcentration of 20.0mL of Cd2+ solution at pH 7.5 (0.1molL-1 buffer phosphate) through 70mg of 3-MPTMS-grafted MWCNTs packed into a minicolumn at 6.0mLmin-1. The elution step was carried out with 1.0molL-1 HCl. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to estimate the extent of the MWCNT chemical modification. The 3-MPTMS-grafted MWCNTs provided a 1.68 times improvement in the sensitivity of the Cd2+ FAAS determination compared to the unsilanized oxidized MWCNTs. The following parameters were obtained: preconcentration factor of 31.5, consumptive index of 0.635mL, sample throughput of 14h-1, and concentration efficiency of 9.46min-1. The analytical curve was constructed in the range of 1.0-60.0μgL-1 (r=0.9988), and the detection and quantification limits were found to be 0.15μgL-1 and 0.62μgL-1, respectively. Different types of water samples and cigarette sample were successfully analyzed, and the results were compared using electrothermal atomic absorption spectrometry (ETAAS) as reference technique. In addition, the accuracy of proposed method was also checked by analysis of certified reference material NIST SRM 1573a (tomato leaves) and standard reference material NIST SRM 1643e (trace elements in natural waters). © 2012 Elsevier B.V.243 326333Soylak, M., Ercan, O., Selective separation and preconcentration of copper (II) in environmental samples by the solid phase extraction on multi-walled carbon nanotubes (2009) J. Hazard. Mater., 168, pp. 1527-1531Parodi, B., Savio, M., Martinez, L.D., Gil, R.A., Smichowski, P., Study of carbon nanotubes and functionalized-carbon nanotubes as substrates for flow injection solid phase extraction associated to inductively coupled plasma with ultrasonic nebulization: application to Cd monitoring in solid environmental samples (2011) Microchem. J., 98, pp. 225-230Zhang, N., Hu, B., Cadmium (II) imprinted 3-mercaptopropyltrimethoxysilane coated stir bar for selective extraction of trace cadmium from environmental water samples followed by inductively coupled plasma mass spectrometry detection (2012) Anal. Chim. Acta, 723, pp. 54-60Proceedings of the meeting of the IARC working group on beryllium, cadmium, mercury and exposures in the glass manufacturing industry (1993) Scand. J. Work. Environ. Health, 19, p. 360. , International Agency for Research on Cancer (IARC)Andac, M., Say, R., Denizli, A., Molecular recognition based cadmium removal from human plasma (2004) J. Chromatogr. B, 811, pp. 119-126(2003) National Primary Drinking Water Standards, Maximum Contaminant Level, , http://water.epa.gov/drink/contaminants/index.cfm%23List, US EPA, United States Environmental Protection Agency Office of Water, (accessed 20.09.12)(2005) CONAMA National Council for the Environment, , http://www.mma.gov.br/port/conama/legiabre.cfm%3Fcodlegi=459, Resolution number 357, (accessed 29.05.12), March 17Buhani, Narsito, Nuryono, Kunarti, E.S., Production of metal ion imprinted polymer from mercapto-silica through sol-gel process as selective adsorbent of cadmium (2010) Desalination, 251, pp. 83-89Vellaichamy, S., Palanivelu, K., Preconcentration and separation of copper, nickel and zinc in aqueous samples by flame atomic absorption spectrometry after column solid-phase extraction onto MWCNTs impregnated with D2EHPA-TOPO mixture (2011) J. Hazard. Mater., 185, pp. 1131-1139Pyrzynska, K., Carbon nanotubes as sorbents in the analysis of pesticides (2011) Chemosphere, 83, pp. 1407-1413Rao, G.P., Lu, C., Su, F., Sorption of divalent metal ions from aqueous solution by carbon nanotubes: a review (2007) Sep. Purif. Tech., 58, pp. 224-231Upadhyayula, V.K.K., Deng, S., Mitchell, M.C., Smith, G.B., Application of carbon nanotube technology for removal of contaminants in drinking water: a review (2009) Sci. Total Environ., 408, pp. 1-13Kosa, S.A., Al-Zhrani, G., Salam, M.A., Removal of heavy metals from aqueous solutions by multi-walled carbon nanotubes modified with 8-hydroxyquinoline (2012) Chem. Eng. J., 181, pp. 159-168Ren, X., Chen, C., Nagatsu, M., Wang, X., Carbon nanotubes as adsorbents in environmental pollution management: a review (2012) Chem. Eng. J., 170, pp. 395-410Afzali, D., Mostafavi, A., Potential of modified multiwalled carbon nanotubes with 1-(2-pyridylazo)-naphthol as a new solid sorbent for the preconcentration of trace amounts of cobalt(II) ion (2008) Anal. Sci., 24, pp. 1135-1139Liu, Y., Li, Y., Yan, X.-P., Preparation Characterization, and application of l-cysteine functionalized multiwalled carbon nanotubes as a selective sorbent for separation and preconcentration of heavy metals (2008) Adv. Funct. Mater., 18, pp. 1536-1543Zang, Z., Hu, Z., Li, Z., He, Q., Chang, X., Synthesis, characterization and application of ethylenediamine-modified multiwalled carbon nanotubes for selective solid-phase extraction and preconcentration of metal ions (2009) J. Hazard. Mater., 172, pp. 958-963Cui, Y., Sh, L., Hu, Z.J., Liu, X.H., Gao, H.W., Solid-phase extraction of lead(II) ions using multiwalled carbon nanotubes grafted with tris(2-aminoethyl)amine (2011) Microchim. Acta, 174, pp. 107-113Kathi, J., Rhee, K., Lee, J.H., Effect of chemical functionalization of multi-walled carbon nanotubes with 3-aminopropyltriethoxysilane on mechanical and morphological properties of epoxy nanocompósitos (2009) Composites A, 40, pp. 800-809Velasco-Santos, C., Martínez-Hernandez, A.L., Lozada-Cassou, M., Alvarez-Castillo, A., Castaño, V.M., Chemical functionalization of carbono nanotubes through an organosilane (2002) Nanotechnology, 13, pp. 495-498Zhou, Z., Wang, S., Lu, L., Zhang, Y., Zhang, Y., Functionalization of multi-wall carbon nanotubes with silane and its reinforcement on polypropylene composites (2008) Comp. Sci. Technol., 68, pp. 1727-1733Liang, X., Xu, Y., Sun, G., Wang, L., Sun, Y., Qin, X., Preparation, characterization of thiol-functionalized silica and application for sorption of Pb2+ and Cd2+ (2009) Colloids Surfaces A Physicochem. Eng. Aspects, 349, pp. 61-68Zougagh, M., Rudner, P.C., de Torres, A.G., Pavon, J.M.C., Application of Doehlert matrix and factorial designs in the optimization of experimental variables associated with the on-line preconcentration and determination of zinc by flow injection inductively coupled plasma atomic emission spectrometry (2000) J. Anal. At. Spectrom., 15, pp. 1589-1594Filho, V.R.A., Polito, W.L., Neto, J.A.G., Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis (2007) J. Br. Chem. Soc., 18, pp. 47-53Barbosa, A.F., Segatelli, M.G., Pereira, A.C., Santos, A.S., Kubota, L.T., Luccas, P.O., Tarley, C.R.T., Solid-phase extraction system for Pb (II) ions enrichment based on multiwall carbon nanotubes coupled on-line to flame atomic absorption spectrometry (2007) Talanta, 71, pp. 1512-1519Long, G.L., Winefordner, J.D., Limit of detection, a closer look at the IUPAC definition (1983) Anal. Chem., 55, pp. 712A-724ATarley, C.R.T., Arruda, M.A.Z., OnLine coupling of a flow injection system to TS-FF-AAS for preconcentration and determination of lead in water and vegetables (2005) Anal. Lett., 38, pp. 1427-1443Nabid, M.R., Sedghi, R., Bagheri, A., Behbahani, M., Taghizadeh, M., Oskooie, H.A., Heravi, M.M., Preparation and application of poly(2-amino thiophenol)/MWCNTs nanocomposite for adsorption and separation of cadmium and lead ions via solid phase extraction (2012) J. Hazard. Mater., 203-204, pp. 93-100Jun-Ping, X., Qing-Xiang, Z., Hua-hua, B.J., Application of multiwalled carbon nanotubes treated by potassium permanganate for determination of trace cadmium prior to flame atomic absorption spectrometry (2007) J. Environ. Sci., 19, pp. 1266-1271Aydemir, N., Tokman, N., Akarsubasi, A.T., Baysal, A., Suleyman, A., Determination of some trace elements by flame atomic absorption spectrometry after preconcentration and separation by Escherichia coli immobilized on multiwalled carbon nanotubes (2011) Microchim. Acta, 175, pp. 185-191Tavallali, H., Fakhraee, V., Preconcentration and determination of trace amounts of Cd2+ using multiwalled carbon nanotubes by solid phase extraction-flame atomic absorption spectrometry (2011) Int. J. Chem. Tech. Res., 3, pp. 1628-1634de F.Lima, G., de Oliveira, F.M., de O.Ohara, M., Segatelli, M.G., Tarley, C.R.T., Evaluation of histidine functionalized multiwalled carbon nanotubes for improvement in the sensitivity of cadmium ions determination in flow analysis (2011) Carbon Nanotubes - From Research to Applications, pp. 67-80. , http://www.intechopen.com/books/carbon-nanotubes-from-research-to-applications/evaluation-of-histidine-functionalized-multiwalled-carbon-nanotubes-for-improvement-in-the-sensitivi, InTech, Available from:, S. Bianco (Ed.)Mohammadi, S.Z., Afzali, D., Pourtalebi, D., Flame atomic absorption spectrometric determination of trace amounts of lead, cadmium and nickel in different matrixes after solid phase extraction on modified multiwalled carbon nanotubes (2010) Cent. Eur. J. Chem., 8, pp. 662-668Mostafavi, A., Farzad, E., Afazali, D., Khabazzadeh, H., Multi-walled carbons nanotubes modified with N-phenyl-1,2-hydrazinedicarbothioamide as a sorbent for separation and preconcentration of trace amounts of cadmium (2009) Chem. Anal., 54, pp. 459-469Liang, H.-D., Han, D.-M., Multi-walled carbon nanotubes as sorbent for flow injection on-line microcolumn preconcentration coupled with flame atomic absorption spectrometry for determination of cadmium and copper (2006) Anal. Lett., 39, pp. 2285-2295