Grafting 3-mercaptopropyl Trimethoxysilane On Multi-walled Carbon Nanotubes Surface For Improving On-line Cadmium(ii) Preconcentration From Water Samples

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.243326333Soylak, 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. 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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. 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Determination Of Phenolic Compounds Based On The Development Of Biosensors Using Nano-estructured Carbon Materials

The enzymatic biosensors present some unique characteristics as low cost, simplicity, selectivity and sensibility, which might turn them attractive for the determination of target compounds in complex matrix, for instance, the environmental ones. The objective of this work is to develop amperometric biosensors for the determination of the concentration of phenolic compounds in environmental samples using carbonaceous materials. It was studied three samples of modified xerogels, two with melamine (FRM2B-PN, HFRM2-PN), one with urea (HFRU2-PN 1/2), besides standard xerogel without modification (Xerogel pH 5.5), carbon nanotubes and graphite. It was also studied the enzymatic activity of the zucchini extract and it was characterized in the prepared paste with the mentioned materials. For the preparation of the electrochemical biosensors, some parameters such as enzymatic extract concentration, hydrogen peroxide concentration, pH and buffer solution were optimized. The higher enzymatic activity was obtained when the enzymatic extract was immobilized onto carbon nanotube. The peroxidase enzyme extracted from several zucchinis (natural source) presented lower activity value than those described in literature and also presented low stability. The amperometric biosensor optimization (work electrode prepared with carbon nanotube paste and enzymatic extract) was evaluated through cyclic voltammetry and it is possible to observe a higher sensibility to the prepared biosensor with 100 μL of enzymatic extract, when the electrochemical measures were made in buffer solution phosphate pH 6.5, containing 10 μmolL-1 of hydrogen peroxide. The activity of the enzymatic extract from the zucchini (natural source) presented low activity, but this extract can still be used in the immobilization of different employed materials. The carbon nanotubes, among the analyzed materials, show the best support for the enzyme immobilization. For the optimization of the biosensor, the result with best sensibility was verified in the electrode prepared with carbon nanotubes paste containing 100 μL of enzymatic extract, when used in a buffer solution phosphate pH 6.5, containing 10 μmolL-1 of hydrogen peroxide. © 2013 Nova Science Publishers, Inc. All rights reserved.333348Belini, A., Filho, O.F., Clemente, E., Braz, J., (2001) Food Technol., 4, p. 75Choi, H.N., Han, J.H., Park, J.A., Lee, J.M., Lee, W.Y., (2007) Electroanalysis, 19, p. 1757Fatibello-Filho, O., Vieira, I.C., (2002) Quim. Nova, 25, p. 455Fiamengos, Y.C., Stalikas, C.D., Pilidis, G.A., Karayannis, M.I., (2000) Anal. Chim. Acta, 403, p. 315Figueiredo, J.L.A., Pereira, M.F.R.A., Serp, P.B., Kalck, P., Samant, P.V., Fernandes, J.B., (2006) Carbon, 44 (12), p. 2516Freire, R.S., Thongngamdee, S., Durán, N., Wang, J., Kubota, L.T., (2002) Analyst, 127, p. 258Gorgulho, H.F., Gonçalves, F., Pereira, M.F.R., Figueiredo, J.L., (2009) Carbon, 47, p. 2032Habermuller, K., Mosbach, M., Schuhmann, W., Resenius, J., (2000) Anal. Chem., 366, p. 560Huang, Y., Duan, X., Wei, Q., Lieber, C.M., (2001) Science, 291, p. 630Job, N., Pirard, R., Marein, J., Pirard, J.P., (2004) Carbon, 42, p. 619Job, N.A., Pereira, M.F.R., Lambert, S., Cabiac, A., Delahay, G., Colomer, J.F., Marien, J., Pirard, J.P., (2006) J. Catal., 240 (2), p. 160Katz, E., Willner, I., (2004) Chem. Phys. Chem., 5, p. 1085Leonard, P., Hearty, S., Brennan, J., Dunne, L., Quinn, J., Chakrborty T.O'Kennedy, R., (2003) Enzyme Microb. Tech., 32, p. 3Liu, R., Zhou, J.L., Wilding, A., (2004) J. Chromatogr. A, 1022, p. 179Lojou, E., Bianco, P., (2006) J. Eletroceram., 16, p. 79Louzada, E.S., Luccas, P.O., Magalhães, C.S., (2004) Analytica, 11, p. 56Pastor-Villegas, J., Duran-Valle, C.J.J., Grzyb, B., Machnikowska, H., Weber, J.V., (2002) Carbon, 40, p. 397Raoof, J.B., Ojani, R., Nadimi, S.R., (2005) Electrochim. Acta, 50, p. 4694Samant, P.V., Fernandes, J.B., Rangel, C.M., Figueiredo, J.L., (2005) Cata. Today, 102, p. 173Silva, R.D.C.L., Damos, F.S., Oliveira, A.B., Beck, J., Kubota, L.T., (2006) Sens. Actuators B, Chem., 117, p. 274Skoog, D.A., Holler, F.J., Nieman, T.A., (2002) Princípios de Análise Instrumental, , 5 ed., BookmanSomerset, V.S., Klink, M.J., Sekota, M.M.C., Baker, P.G.L., Iwuoha, E.I., (2006) Anal. Chim. Acta, 39, p. 1683Tsai, Y.C., Chen, S.Y., Lian, H.W., (2007) Sens Actuators, 125, p. 474Whitney, T.M., Jiang, J.S., Searson, P.C., Chien, C.L., (1993) Science, 261, p. 26

Cloud Point Extraction/preconcentration Of Copper Ions Exploiting The Formation Of Complexes With Dmit [4,5-dimercapto-1,3-dithyol-2-thionate] [extração/pré-concentração De íons Cobre No Ponto Nuvem Explorando A Formação De Complexos Com Dmit [4,5-dimercapto-1,3-ditiol-2-tionato]]

The present study proposes a method for cloud point preconcentration of copper ions at pH 2.0 based on complexes formed with [4,5-dimercapto-1,3- dithyol-2-thionate] and subsequent determination by flame atomic absorption spectrometry (FAAS). Under optimal analytical conditions, the method provided limits of detection of 0.84 and 0.45 mg L-1, by preconcentrating 12.0 and 24.0 mL of sample, respectively. The method was applied for copper determination in water samples, synthetic saliva, guarana powder, tea samples and soft drinks and the accuracy was assessed by analyzing the certified reference materials Dogfish Liver (DOLT-4) and Lobster Hepatopancreas (TORT-2).35816001605Nascentes, C.C., Arruda, M.A.Z., Maniasso, N., (2002) Quim. Nova, 25, p. 483Bezerra, M.A., Ferreira, S.L.C., (2006) Extração em Ponto Nuvem: Princípios e Aplicações e Química Analítica, , 1a ed., Edições UESB: Vitória da ConquistaSussulini, A., Arruda, M.A.Z., (2006) Eclet. Química, 31, p. 73Wang, L., Cai, Y., He, B., Yuan, C., Shen, D., Shao, J., Jiang, G., (2006) Talanta, 70, p. 47Paleólogos, E.K., Giokas, D.L., Karayannis, M.I., (2005) Trends Anal. Chem., 24, p. 426Bezerra, M.D., Arruda, M.A.Z., Ferreira, S.L.C., (2005) Appl. Spectrosc. Rev., 40, p. 269Citak, D., Tuzen, M., (2010) Food Chem. Toxicol., 48, p. 1399Ghaedi, M., Shokrollahi, A., Ahmadi, F., Rajabi, H.R., Soylak, M., (2008) J. Hazard. Mater., 150, p. 533Satiroglu, N., Arpa, C., (2008) Microchim. Acta, 162, p. 107Lemos, V.A., Santos, M.S., David, G.T., Maciel, M.V., Bezerra, M.A., (2008) J. Hazard. Mater., 159, p. 245Ghaedi, M., Shokrollahi, A., Niknam, K., Nikam, E., Najibi, A., Soylak, M., (2009) J. Hazard. Mater., 168, p. 1022Bezerra, M.A., Bruns, R.E., Ferreira, S.L.C., (2006) Anal. Chim. Acta, 580, p. 251Lemos, V.A., Santos, M.S., Dos Santos, J.S., Vieira, D.R., Novaes, C.G., (2007) Microchim. Acta, 157, p. 215Silva, E.L., Roldan, P.S., Giné, M.F., (2009) J. Hazard. Mater., 171, p. 1133Kolachi, N.F., Kazi, T.G., Khan, S., Wadhwa, S.K., Baig, J.A., Afridi, H.I., Shah, A.Q., Shah, F., (2011) Food Chem. Toxicol., 49, p. 2548Chen, J., Teo, K.C., (2001) Anal. Chim. Acta, 450, p. 215Amais, R.S., Tarley, C.R.T., (2008) Can. J. Anal. Sci. Spectrosc., 53, p. 130Souza, J.M.O., Tarley, C.R.T., (2008) Anal. Lett., 41, p. 2465Barreto, W.J., Ribeiro, M.C.C., Santos, P.S., (1992) J. Mol. Struct., 269, p. 7584Barreto, W.J., Barreto, S.R.G., Ruiz, L.D., Ishikawa, D.N., Scarmínio, I.S., (2005) Anal. Sci., 21, p. 549Barreto, S.R.G., Nozaki, J., Barreto, W.J., (1999) Microchem. J., 62, p. 223Sargentelli, V., Mauro, A.E., Massabni, A.C., (1996) Quim. Nova, 19, p. 290Khairy, M., Kadara, R.O., Kampouris, D.K., Banks, C.E., (2010) Anal. Methods, 2, p. 645Oliveira, F.M., Somera, B.F., Corazza, M.Z., Segatelli, M.G., Ribeiro, E.S., Lima, E.C., Dias, S.L.P., Tarley, C.R.T., (2011) Talanta, 85, p. 2417Barros Neto, B., Scarmínio, I.S., Bruns, R.E., (1996) Planejamento e Otimização de Experimentos, , 2a ed., Editora Unicamp: CampinasRalph, G.P., (1963) J. Am. Chem. Soc., 85, p. 3533Long, G.L., Winefordner, J.D., (1983) Anal. Chem., 55, p. 712Watanabe, K., Tanaka, T., Shigeni, T., Hayashida, Y., Maki, K., (2009) J. Trace Elem. Med. Biol., 23, p. 93Hong, J.E., Duncan, S.E., Dietrich, A.M., O'Keefe, S.F., Eigel, W.N., Mallikarjunan, K., (2009) J. Agric. Food Chem., 57, p. 6967Harris, D.C., (2005) Análise Química Quantitativa, , 6a ed., LTC-Livros Técnicos e Científicos Ed. S. A.: Rio de JaneiroKulichenko, S.A., Doroschuk, V.O., Lelyshok, S.O., (2003) Talanta, 59, p. 767Shokrollajo, A., Ghaedi, M., Hossaini, O., Khanjari, N., Soylak, M., (2008) J. Hazard. Mat., 160, p. 435Gao, Y., Wu, P., Li, W., Xuan, Y., Hou, X., (2010) Talanta, 81, p. 58

On-line micro-solid phase preconcentration of Cd2 + coupled to TS-FF-AAS using a novel ion-selective bifunctional hybrid imprinted adsorbent

A novel hybrid ion imprinted polymer (HIIP) is proposed aiming at the development of an online micro-solid phase preconcentration system of Cd2 + coupled to TS-FF-AAS. To evaluate the selective and adsorptive performance of HIIP towards Cd2 +, hybrid non-imprinted polymer (HNIP), organic ion imprinted polymer (OIIP), and the inorganic ion imprinted polymer (IIIP) were synthesized and compared with each other. Adsorption capacity of HIIP was 53% higher than HNIP, and dual-site Langmuir–Freundlich isotherm model showed the best fit for data of both polymers. The preconcentration system coupled to TS-FF-AAS was performed by loading 10.0 mL of Cd2 + solution at pH 7.5 through 80.0 mg of HIIP packed into a micro-column with posterior online elution using 1.0 mol L− 1 HCl/ethanol 1:1 (v/v) mixture. The developed method was highly tolerant for other metal ions Zn2 +, Pb2 +, Cu2 +, Co2 +, Fe2 +, and Hg2 + at analyte:interferent (1:50, m/m) ratio and Ca2 + and Mg2 + at 1:500 (m/m) ratio. Analytical curve ranging from 0.5 to 7.0 μg L− 1, limit of detection of 30 ng L− 1 and preconcentration factor of 14-fold were obtained. Intra-day and inter-day (3 days) experiment precision (n = 10) was, respectively, 3.9 and 0.6% (relative standard deviation, RSD), and 4.4 and 2.4% for concentrations of 0.7 and 6.5 μg L− 1. Sensitivity of method (Abs L μg− 1) was about 3.3, 2.2 and 1.9-fold higher when compared to preconcentration method using HNIP, OIIP and IIIP, respectively, thus clearly showing that hybrid polymer and imprinting process enhance Cd2 + adsorption. Addition and recovery experiments ranging from 94 to 106% in mineral, lake water and tap water, urine and cigarette samples attested the feasibility of method for analysis of matrices containing different components. Moreover, the accuracy of method was checked from analysis of certified reference material (DOLT-4, fish liver), being the obtained value of 23.9 ± 0.6 mg kg− 1 (n = 3) statistically equal to the certified value of 24.3 ± 0.8 mg kg− 1, by applying Student t-test at 95% confidence level.1315769CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES481669/2013-2; 305552/2013-9; 472670/2012-325/201

3-mercaptopropyltrimethoxysilane-modified Multi-walled Carbon Nanotubes As A New Functional Adsorbent For Flow Injection Extraction Of Pb(ii) From Water And Sediment Samples

In the present study, a novel synthesized adsorbent material based on 3-mercaptopropyltrimethoxysilanefunctionalized multi-walled carbon nanotubes was used to increase the Pb2+ adsorption from aqueous solutions in a flow injection solid-phase extraction system coupled to flame atomic absorption spectrometry. Spectroscopic and microscopic techniques (Fourier transform infrared spectroscopy, energy dispersive spectroscopy, and scanning electronmicroscopy) were employed to confirm the chemical modification of the adsorbent surface. Preconcentration conditions (sample pH, flow rate, buffer solution, and eluent concentrations) were optimized using factorial and Doehlert matrix designs that made it possible to construct a linear graph in the 5.0- to 130.0-μgL-1 range (r0 0.9999) and estimate detection and quantification limits (1.7 and 5.7 μgL-1, respectively). The method precision was found to be 4.20 and 1.97%for 5.0 and 100.0 μgL -1 Pb2+ solutions, respectively. When using the 3-mercaptopropyltrimethoxysilane-functionalized multiwalled carbon nanotubes, the sensitivity for the Pb2+ trace determination was improved to 95 % compared with the oxidized multi-walled carbon nanotubes, thus evidencing the significant enhancement of the adsorption capacity. 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On-line Micro-solid Phase Preconcentration Of Cd2 + Coupled To Ts-ff-aas Using A Novel Ion-selective Bifunctional Hybrid Imprinted Adsorbent

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A novel hybrid ion imprinted polymer (HIIP) is proposed aiming at the development of an online micro-solid phase preconcentration system of Cd2 + coupled to TS-FF-AAS. To evaluate the selective and adsorptive performance of HIIP towards Cd2 +, hybrid non-imprinted polymer (HNIP), organic ion imprinted polymer (OIIP), and the inorganic ion imprinted polymer (IIIP) were synthesized and compared with each other. Adsorption capacity of HIIP was 53% higher than HNIP, and dual-site Langmuir–Freundlich isotherm model showed the best fit for data of both polymers. The preconcentration system coupled to TS-FF-AAS was performed by loading 10.0 mL of Cd2 + solution at pH 7.5 through 80.0 mg of HIIP packed into a micro-column with posterior online elution using 1.0 mol L− 1 HCl/ethanol 1:1 (v/v) mixture. The developed method was highly tolerant for other metal ions Zn2 +, Pb2 +, Cu2 +, Co2 +, Fe2 +, and Hg2 + at analyte:interferent (1:50, m/m) ratio and Ca2 + and Mg2 + at 1:500 (m/m) ratio. Analytical curve ranging from 0.5 to 7.0 μg L− 1, limit of detection of 30 ng L− 1 and preconcentration factor of 14-fold were obtained. Intra-day and inter-day (3 days) experiment precision (n = 10) was, respectively, 3.9 and 0.6% (relative standard deviation, RSD), and 4.4 and 2.4% for concentrations of 0.7 and 6.5 μg L− 1. Sensitivity of method (Abs L μg− 1) was about 3.3, 2.2 and 1.9-fold higher when compared to preconcentration method using HNIP, OIIP and IIIP, respectively, thus clearly showing that hybrid polymer and imprinting process enhance Cd2 + adsorption. Addition and recovery experiments ranging from 94 to 106% in mineral, lake water and tap water, urine and cigarette samples attested the feasibility of method for analysis of matrices containing different components. Moreover, the accuracy of method was checked from analysis of certified reference material (DOLT-4, fish liver), being the obtained value of 23.9 ± 0.6 mg kg− 1 (n = 3) statistically equal to the certified value of 24.3 ± 0.8 mg kg− 1, by applying Student t-test at 95% confidence level. © 2016 Elsevier B.V.1315769163/2014, Fundação Araucária25/2014, CAPES, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior305552/2013-9, CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico472670/2012-3, CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico481669/2013-2, CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoSETI, Secretário de Ciência, Tecnologia e Ensino Superior, Governo do Estado de ParanaCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Kinetic And Isotherm Studies Of Ni2+adsorption On Poly(methacrylic Acid) Synthesized Through A Hierarchical Double-imprinting Method Using A Ni2+ Ion And Cationic Surfactant As Templates

A novel poly(methacrylic acid) material (IIP/CTAB) was prepared by a hierarchical double-imprinting process with Ni2+ ion and cationic surfactant - cetyltrimethylammonium bromide (CTAB) as templates, and it was employed to adsorb Ni2+ ions from aqueous medium. Other poly(methacrylic acid) materials - single-imprinted (IIP/no CTAB) and nonimprinted (NIP/no CTAB) were investigated in adsorption studies. All the synthesized polymers were characterized by FTIR, SEM, and nitrogen adsorption-desorption isotherm. The maximum Ni2+ adsorption capacities of IIP/CTAB and NIP/no CTAB were found to be 33.31 and 18.64 mg g-1, respectively, at pH 7.25. The relative selectivity coefficient (k′) values for Ni2+/Cu2+, Ni2+/Mn +, Ni2+/Co2+ and Ni2+/Pb 2+ systems were higher than 1, thus confirming the significant improvement in the selectivity of the polymer. 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