Synthesis, characterization and application of ion imprinted poly(vinylimidazole) for zinc ion extraction/preconcentration with faas determination

In this paper, we describe the synthesis of an ion imprinted polymer (IIP) by homogeneous polymerization and its use in solid-phase to extract and preconcentrate zinc ions. Under optimal conditions (pH 5.0, preconcentration flow rate of 12.0 mL min-1, and eluted with 1.0 mol L-1 HNO3) this procedure allows the determination of zinc with an enrichment factor of 10.2, and with limits of detection and quantification of 1.5 and 5.0 µg L-1, respectively. The accuracy of our results was confirmed by analysis of tap water and certified reference materials: NIST 1570a (Spinach leaves) and NIST 1515 (Apple leaves)371636

Application of chitosan functionalized with 3,4-dihydroxy benzoic acid moiety for on-line preconcentration and determination of trace elements in water samples

Chitosan resin functionalized with 3,4-dihydroxy benzoic acid (CCTS-DHBA resin) was used as a packing material for flow injection (FI) on-line mini-column preconcentration in combination with inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the determination of trace elements such as silver, bismuth, copper, gallium, indium, molybdenum, nickel, uranium, and vanadium in environmental waters. A 5-mL aliquot of sample (pH 5.5) was introduced to the minicolumn for the adsorption/preconcentration of the metal ions, and the collected analytes on the mini-column were eluted with 2 M HNO3, and the eluates was subsequently transported via direct injection to the nebulizer of ICP-AES for quantification. The parameters affecting on the sensitivity, such as sample pH, sample flow rate, eluent concentration, and eluent flow rate, were carefully examined. Alkali and alkaline earth metal ions commonly existing in river water and seawater did not affect the analysis of metals. Under the optimum conditions, the method allowed the determination of metal ions with detection limits of 0.08 ng mL(-1) (Ag), 0.9 ng mL(-1) (Bi), 0.07 ng mL(-1) (Cu), 0.9 ng mL(-1) (Ga), 0.9 ng mL(-1) (In), 0.08 ng mL(-1) (Mo), 0.09 ng mL(-1) (Ni), 0.9 ng mL(-1) (U), and 0.08 ng mL(-1) (V). By using 5 mL of sample solution, the enrichment factor and collection efficiency were 8-12 fold and 96-102%, respectively, whereas the sample throughput was 7 samples/hour. The method was validated by determining metal ions in certified reference material of river water (SLRS-4) and nearshore seawater (CASS-4), and its applicability was further demonstrated to river water and seawater samples.</p

Preparation of a new restricted access molecularly imprinted hybrid adsorbent for the extraction of folic acid from milk powder samples

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A new hybrid molecularly imprinted polymer (MIP) combined with restricted access (RAM) has been synthesized based on random free-radical polymerization and a sol-gel process. From competitive adsorption studies by using the RAM-MIP and RAM-NIP with folic acid and structurally similar molecules (caffeine, 4-aminobenzamide or paracetamol), relative selectivity coefficients (k) higher than one unit were achieved, indicating good recognition selectivity for folic acid. The percentage of BSA protein exclusion was higher for the RAM-MIP (55.3 + 2.0) as compared to the MIP (35.9 + 2.5%). The solid phase extraction (SPE) procedure was performed by loading the acid extract from milk powder samples previously submitted to saponification and acidification with 10% trichloroacetic acid (TCA) until pH 1.5, through 100 mg of RAM-MIP packed into SPE cartridge. The elution step was carried out by using a mixture of acetonitrile : 0.266 mol L-1 acetate buffer at pH 5.7 (15 : 85, v/v), the same composition of the mobile phase of HPLC. The intra-day precision (n = 10) of the procedure assessed as relative standard deviation (RSD) was 4.7 and 4.1% for the respective concentrations of 20.0 and 150.0 mu g L-1. The applicability of the method was attested by analysis of different brands of milk powder samples fortified with folic acid, as well as by high recovery percentages 95.0-108.4% obtained upon addition and recovery tests. The cleanup process accomplished by RAM-MIP was so efficient that very few remaining matrix components were detected in the eluate by high performance liquid chromatography.A new hybrid molecularly imprinted polymer (MIP) combined with restricted access (RAM) has been synthesized based on random free-radical polymerization and a sol–gel process. From competitive adsorption studies by using the RAM-MIP and RAM-NIP with folic83656665COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO ARAUCÁRIA DE APOIO AO DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO DO PARANÁ - FACONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)sem informaçãosem informaçãosem informaçãoWe acknowledge the CAPES, INCT-BIOANALITICA, FUNDAÇÃO ARAUCÁRIA do PARANÁ, SETI do Paraná and CNPq for financial support. The authors also would like to thank all the anonymous reviewers for their valuable comments and suggestions to improve the quality

Preparation of molecularly imprinted poly(methacrylic acid) grafted on iniferter-modified multiwalled carbon nanotubes by living-radical polymerization for 17β-Estradiol Extraction

The synthesis of a nanocomposite based on molecularly imprinted poly(methacrylic acid) (MIP) grafted on an iniferter-modified carbon nanotube (MIP/MWCNT) by living-radical polymerization and its application for 17β-estradiol (E2) adsorption is described. The nonimprinted nanocomposite (NIP/MWCNT) and the polymers MIP and NIP synthesized in the absence of carbon nanotubes were also prepared and characterized by FT-IR, TGA, nitrogen adsorption–desorption measurements, and SEM and TEM techniques. From TEM images, a narrow layer of MIP at nanoscale onto MWCNT surface was formed, as expected by iniferter-controlled synthesis. The adsorption capacity of MIP/MWCNT toward E2 was higher than MIP. In addition, relative selectivity coefficients (k′) higher than one unit were obtained from competitive adsorption studies in the presence of estrone, 17α-ethynylestradiol, and bisphenol A, thereby demonstrating that MIP/MWCNT is more selective toward E2 when compared to NIP/MWCNT. Equilibrium adsorption of E2 was reached at 120 min and the maximum adsorption capacity of the nanocomposite was found to be 40.0 mg g–1, showing higher or similar performance when compared with others adsorbent materials described on the literature for E2. Thermodynamic parameters suggest that the adsorption process is spontaneous and of exothermic nature. The performance of MIP/MWCNT as a new packing adsorbent material was evaluated for E2 extraction in solid-phase extraction (SPE) procedure, which was performed by loading the sample at pH 7.0 through 50.0 mg of MIP/MWCNT packed into SPE cartridge. Taking into account the high elution value of 96 ± 3.6% obtained by using acetone:chloroform (1:1 v/v), as well as the selectivity of adsorbent, we can infer that MIP/MWCN/T nanocomposite shows interesting analytical potentiality for E2 preconcentration from natural water samples64519781990CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP481669/2013-2; 305552/2013-9; 472670/2012-3; 465389/2014-73353/2014; 23038.007082/2014-032014/50867-3The authors acknowledge the financial support and fellowships of Coordenação de Aperfeiçoamento de Nível Superior (CAPES) (Project Pró-Forenses 3353/2014 Grant 23038.007082/2014-03), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (Grants 481669/2013-2, 305552/2013-9, 472670/2012-3), Fundação Araucária do Paraná (163/2014), SETI do Paraná, and Instituto Nacional de Ciência e Tecnologia de Bioanalítica (INCT) (FAPESP Grant 2014/50867-3 and CNPq Grant 465389/2014-7

Uso de planejamento experimental na otimização de um sistema de pré-concentração em fase sólida para a determinação de cobalto por GFAAS

In this work is proposed a solid phase preconcentration system of Co2+ ions and its posterior determination by GFAAS in which fractional factorial design and response surface methodology (RSM) were used for optimization of the variables associated with preconcentration system performance. The method is based on cobalt extraction as a complex Co2+-PAN (1:2) in a mini-column of polyurethane foam (PUF) impregnated with 1-(2-pyridylazo)-naphthol (PAN) followed by elution with HCl solution and its determination by GFAAS. The chemical and flow variables studied were pH, buffer concentration, eluent concentration and preconcentration and elution flow rates. Results obtained from fractional factorial design 2(5-1) showed that only the variables pH, buffer concentration and interaction (pH X buffer concentration) based on analysis of variance (ANOVA) were statistically significant at 95% confidence level. Under optimised conditions, the method provided an enrichment factor of 11.6 fold with limit of detection and quantification of 38 and 130 ng L-1, respectively, and linear range varying from 0.13 to 10 µg L-1. The precision (n = 9) assessed by relative standard deviation (RSD) was respectively 5.18 and 2.87% for 0.3 and 3.0 µg L-1 cobalt concentrations.No presente trabalho é proposto um sistema de pré-concentração em fase sólida de íons Co2+ com posterior determinação por GFAAS, cuja otimização das variáveis associadas ao desempenho do sistema de pré-concentração foi realizada por planejamento fatorial fracionário e metodologia de superfície de resposta (MSR). O método é baseado na extração de cobalto como um complexo Co2+-PAN (1:2) em uma mini-coluna de espuma de poliuretano (EPU) impregnada com 1-(2-piridilazo)-naftol (PAN) seguido pela eluição com solução de HCl e determinação por GFAAS. As variáveis químicas e de fluxo estudadas foram pH, concentração do tampão, concentração do eluente e vazões de pré-concentração e eluição. Os resultados obtidos a partir do planejamento fatorial fracionário 2(5-1) mostraram, com base na análise de variância (ANOVA), que apenas as variáveis pH, concentração do tampão e a interação (pH X concentração do tampão) foram estatisticamente significativas com nível de 95% de confiança. Nas condições otimizadas, o método forneceu um fator de enriquecimento de 11,6 vezes com respectivos limites de detecção e quantificação de 38 e 130 ng L-1 e faixa linear variando de 0,13 a 10 mg L-1. A precisão (n=9) avaliada em termos de desvio padrão relativo (DPR) foi respectivamente de 5,18 e 2,87% para concentrações de cobalto de 0,3 e 3,0 mg L-1.6574Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Synthesis and application of restricted access material-ion imprinted poly (allylthiourea) for selective separation of Cd2+ and humic acid exclusion

A new restricted access cadmium ion-imprinted poly(allythiourea) was synthesized and evaluated as sorbent for Cd2+ preconcentration with simultaneous exclusion of humic acid (HA). Restricted access medium-ion imprinted polymer was assessed by using the co-monomer 2-hydroxyethyl methacrylate (HEMA) as well as by surface coating with bovine serum albumin (BSA). A set of techniques were used for sorbent characterization including, Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), CHNS/O elemental analysis, Thermogravimetric Analysis (TGA), N-2 physisorption to obtain textural data, swelling effect analysis (SE) and wettability. HP modified with HEMA and HP modified with HEMA-BSA, compared with IIP showed better performance in binding Cd2+ and simultaneous HA exclusion. However, based on relative selectivity coefficient (k'), the selective sorption of Cd2+ and efficient HA exclusion was achieved by using HP-HEMA. The obtained results demonstrate that coating of BSA onto IIP surface is unnecessary for preparing restricted material medium-ion imprinted polymer as well as decreases the selectivity of imprinted polymer. Therefore, the insertion of HEMA in the synthesis of TIP has been the best strategy to obtain a highly selective ion imprinted polymer with restricted access very promising for practical application in the interference-free determination of Cd2+ in natural waters13493103CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO ARAUCÁRIA DE APOIO AO DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO DO ESTADO DO PARANÁ - FAFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP481669/2013-2; 305552/2013-9; 472670/2012-3; 465389/2014-73353/201;, 23038.007082/2014-03163/20142014/50867-