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On line pre-concentration for simultaneous determination of low molecular weight organic acids and inorganic anions in Amazonian river water samples employing ion chromatography with conductivity detection; Pré-concentração em linha para a determinação simultânea de ácidos carboxílicos de baixo peso molecular e ânions inorgânicos em amostras de rios da Amazônia empregando cromatografia de íons com detecção por condutividade elétrica

TUMANG, Cristiane Azevedo; KRUSCHE, Alex Vladimir; VICTORIA, Reynaldo Luis; RICHEY, Jeffrey Edward
Fonte: Instituto Nacional de Pesquisas da Amazônia Publicador: Instituto Nacional de Pesquisas da Amazônia
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
559.9425%
An ion chromatography procedure, employing an IonPac AC15 concentrator column was used to investigate on line preconcentration for the simultaneous determination of inorganic anions and organic acids in river water. Twelve organic acids and nine inorganic anions were separated without any interference from other compounds and carry-over problems between samples. The injection loop was replaced by a Dionex AC15 concentrator column. The proposed procedure employed an auto-sampler that injected 1.5 ml of sample into a KOH mobile phase, generated by an Eluent Generator, at 1.5 mL min-1, which carried the sample to the chromatographic columns (one guard column, model AG-15, and one analytical column, model AS15, with 250 x 4mm i.d.). The gradient elution concentrations consisted of a 10.0 mmol l-1 KOH solution from 0 to 6.5 min, gradually increased to 45.0 mmol l-1 KOH at 21 min., and immediatelly returned and maintained at the initial concentrations until 24 min. of total run. The compounds were eluted and transported to an electro-conductivity detection cell that was attached to an electrochemical detector. The advantage of using concentrator column was the capability of performing routine simultaneous determinations for ions from 0.01 to 1.0 mg l-1 organic acids (acetate...

Evaluation of a simple hyphenated system for flow injection solid-phase pre-concentration and capillary electrophoresis

ASSUNÇÃO, Nilson A.; MIRANDA, Carlos E. S.; LANÇAS, Fernando M.; ROSIAS, Maria Fernanda G. G.; CARRILHO, Emanuel
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
462.16336%
In this work, the development and evaluation of a hyphenated flow injection-capillary electrophoresis system with on-line pre-concentration is described. Preliminary tests were performed to investigate the influence of flow rates over the analytical signals. Results revealed losses in terms of sensitivity of the FIA-CE system when compared to the conventional CE system. To overcome signal decrease and to make the system more efficient, a lower flow rate was set and an anionic resin column was added to the flow manifold in order to pre-concentrate the analyte. The pre-concentration FIA-CE system presented a sensitivity improvement of about 660% and there was only a small increase of 8% in total peak dispersion. These results have confirmed the great potential of the proposed system for many analytical tasks especially for low concentration samples.; Nesse trabalho apresentamos um sistema hifenizado envolvendo as duas técnicas analíticas: eletroforese capilar (CE) e análises por injeção em fluxo (FIA), denominado de FIA-CE. Parâmetros como a influência do fluxo e a natureza do eluente frente ao sistema CE foram avaliados. O sistema demonstrou-se promissor quanto à possibilidade de aplicações em diferentes áreas da química analítica. O aumento da sensibilidade foi da ordem de 660% devido ao emprego de colunas de troca iônica no sistema FIA. Esse resultado comprova o grande potencial do sistema FIA-CE.; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPq; FAPESP

Comparação das metodologias de extração no ponto nuvem e extração em fase sólida para a determinação de cádmio em amostras de águas; Comparison of methodologies for cloud point extraction and solid phase extraction for determination of cadmium in water samples

Ramella, Jéssica Correia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/10/2009 PT
Relevância na Pesquisa
466.83094%
Apresenta-se a comparação de duas metodologias para pré-concentração e determinação de Cd em amostras de águas estuarinas e água de mar. As metodologias comparadas foram a extração líquido-líquido no ponto nuvem e a extração por retenção dos analitos em fase sólida. Em ambos os métodos houve necessidade de formação de complexos de Cd previamente à extração. Dois agentes complexantes foram testados o O-O dietilditiofosfato (DDTP), e 1-(2- tiazolilazo)-2-naftol (TAN). A extração no ponto nuvem foi realizada utilizando o surfactante não iônico octil fenoxipolietoxietanol (Triton X-114) que à temperatura de '40 graus'C forma uma fase micelar viscosa de volume reduzido. Após separação das micelas, estas foram dissolvidas em solução de ácido nítrico facilitando a análise por ICP OES. A pré-concentração em fase sólida por retenção dos íons complexados foi realizada colocando-se uma coluna de Amberlite XAD 4 em sistema em fluxo. Foram ajustadas as vazões de carregamento da coluna e eluição de forma a aumentar os fatores de pré-concentração. Os volumes das soluções finais foram de 2 mL de forma a obter resultados em triplicata na análise por ICP OES. A quantificação foi efetuada pelo método das adições de padrão. Os dois procedimentos foram comparados considerando as eficiências relativas de pré-concentração...

Identificação e pré-concentração dos produtos da fotodegradação de antimicrobianos; Identification and pre-concentration on the photodegradation products of antimicrobials

Ferreira, Tanare Cambraia Ribeiro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/10/2014 PT
Relevância na Pesquisa
466.28043%
A identificação de intermediários formados durante os processos de tratamentos de efluentes tem se tornado alvo de estudos. Entretanto, uma das questões mais importantes nos estudos de intermediários formados durante a fotólise ou degradação de fármacos por processos oxidativos avançados publicados atualmente é a concentração inicial utilizada. Altas concentrações dificultam a compreensão da real situação que ocorre na natureza, onde esses compostos são encontrados em baixas concentrações. Dentro deste contexto, o presente estudo, avaliou a pré-concentração de intermediários formados durante a fotólise em solução aquosa e em esgoto sintético da sulfametazina (SMZ), do ciprofloxacino (CIP) e do enrofloxacino (ENR) em diferentes concentrações (25 mg L-1 e 250 μg L-1 para SMZ; 10 mg L-1 e 100 μg L-1 para CIP e ENR) utilizando espectromatria de massas sequencial de alta resolução (Q-ToF e LIT-Orbitrap MS). Foram identificados oito intermediários da fotodegradação da SMZ, dentre estes os de m/z nominal 140 e 229 ainda não relatados na literatura. A metodologia desenvolvida para a SMZ foi aplicada a análises de produtos de transformação vindos de reator anaeróbio. As análises da biodegradação da SMZ permitiram a identificação de três produtos de transformação. O m/z 295 foi comum aos dois processos...

Pre-concentration of Cd(II), Cr(III), Cu(II) and Ni(II) on a column packed with oxycellulose.

Padilha, P. D.; Federici, C. D.; Campos, JTD; Moreira, J. C.
Fonte: Editora Unesp Publicador: Editora Unesp
Tipo: Artigo de Revista Científica Formato: 61-67
POR
Relevância na Pesquisa
661.526%
Oxycellulose (OXICEL) was packed in a glass column to pre-concentrate metal cations from aqueous solutions. The pre-concentrated metal cations are directly eluted from the column using 5.0 mL of 1.0 mol L(-1) hydrochloric acid. The optimum pre-concentration conditions are given and the retention efficency achieved is higher than 95%. The enrichment factor is 10 for sample volumes of 50 mL.

Pre-concentration of Cd(II), Cr(III), Cu(II) and Ni(II) on a column packed with free carboxymethylcellulose (CMCH)

Padilha, Pedro de Magalhães; Rocha, Julio Cesar; Campos, Joaquim T.S.; Moreira, José Celso; Federici, Cilene C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 333-337
ENG
Relevância na Pesquisa
661.526%
Carboxymethylcellulose packed in to a glass column was used to pre-concentrate metallic cations from aqueous solutions. The pre-concentrated metal cations are directly eluted from the column using 5.0 mL of 1.0 mol L -1 hydrochloric acid. The optimum pre-concentration conditions are given (glass column, 16 cm length, 0.80 cm i.d., stationary phase height of 12 cm, flow-rate, 1.5 mL min -1). The recuperation efficiency achieved is greater than 95%, while the enrichment factor is 10 for 50 mL of solution (0.50 mg L -1 each).

Determination of Cu, Ni and Pb in Aqueous Medium by FAAS after Pre-Concentration on 2-Aminothiazole Modified Silica Gel

De Alcântara, Ilton Luiz; Dos Santos Roldan, Paulo; Margionte, Maurício A. L.; Castro, Gustavo R.; Padilha, Cilene C. F.; De Oliveira Florentino, Ariovaldo; De Magalhães Padilha, Pedro
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 366-371
ENG
Relevância na Pesquisa
663.6355%
This work describes the synthesis and characterization of 2-aminothiazole modified silica gel (SiAT), and the results of a study of the adsorption and pre-concentration (in batch and using a flow-injection system coupled to an absorption atomic spectrometer) of Cu(II), Ni(II) and Pb(II) in aqueous medium. The adsorption capacities for each metal ions in mmol g -1 were: Cu(II)= 1.18, Ni(II)= 1.15 and Pb(II)= 1.10. The results obtained in the flow experiments showed a recovery of practically 100% of the metal ions adsorbed in a mini-column packed with 100 mg of SiAT, using 100 μL of 2.0 mol L -1 HCl solution as eluent. The sorption-desorption of the metal ions made possible the application of a flow-injection system for the pre-concentration and quantification by FAAS of metal ions at trace level in natural water samples digested and not digest by an oxidizing UV photolysis.

Incorporation of dithiooxamide as a complexing agent into cellulose for the removal and pre-concentration of Cu(II) and Cd(II) ions from natural water samples

Jorgetto, A. O.; Silva, R. I V; Longo, M. M.; Saeki, M. J.; Padilha, P. M.; Martines, M. A U; Rocha, B. P.; Castro, G. R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 368-374
ENG
Relevância na Pesquisa
662.16336%
The present study describes the incorporation of a complexing agent, dithiooxamide, into microcrystalline cellulose for use in the pre-concentration of Cu(II) and Cd(II) ions from aqueous samples. The FTIR spectrum of the adsorbent exhibited an absorption band in the region of 800 cm-1, which confirmed the binding of the silylating agent to the matrix. Elemental analysis indicated the amount of 0.150 mmol g-1 of the complexing agent. The adsorption data were fit to the modified Langmuir equation, and the maximum amount of metal species extracted from the solution, Ns, was determined to be 0.058 and 0.072 mmol g-1 for Cu(II) and Cd(II), respectively. The covering fraction φ, which was 0.39 and 0.48 for Cu(II) and Cd(II), respectively, was used to estimate a 1:2 (metal:ligand) ratio in the formed complex, and a binding model was proposed based on this information. The adsorbent was applied in the pre-concentration of natural water samples and exhibited an enrichment factor of approximately 50-fold for the species studied, which enabled its use in the analysis of trace metals in aqueous samples. The system was validated by the analysis of certified standard (1643e), and the adsorbent was stable for more than 20 cycles, thus enabling its safe reutilization. © 2012 Elsevier B.V. All rights reserved.

Pre-concentração por electrostacking e por ponto nuvem para determinação de arsenio e cadmio em amostras ambientais e biologicas; Pre-concentration by electrostacking and by cloud point for determination of metallic ions in environmental and biological samples

Luciana Melo Coelho
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/06/2005 PT
Relevância na Pesquisa
576.4488%
É proposto neste trabalho de Tese o estudo de dois sistemas de pré-concentração para determinação de espécies metálicas por espectrometria de absorção atômica por chama (FAAS) e espectrometria de absorção atômica com atomização eletrotérmica (ETAAS). Primeiramente, é investigado o uso do sistema de "electrostacking" bidirecional (BDES) para a pré-concentração e especiação de As(V) e As total em amostras de água utilizando a técnica ETAAS. Neste sistema, As(V) é pré-concentrado mediante a aplicação de diferença de potencial, como ocorre na eletroforese capilar (CE). As variáveis investigadas no intuito de otimizar a pré-concentração de As são: zona de amostragem (alíquotas de 150 mL coletadas seqüencialmente), dimensão do tubo da amostra (12,4 e 4,1 cm de comprimento), voltagem (500, 750 e 1000 V), tempo de aplicação da voltagem (5, 10, 15, 20 e 40 min), pH da amostra (4,0; 7,0; 8,0 e 12,0), natureza da solução tampão (Tris/HCI, glicina/NaOH e H3BO3/NaOH) e concentração da solução tampão (0,05 - 0,2 mol L). Sendo assim, as melhores condições para pré-concentração de As(V) são: voltagem aplicada de 750 V durante 20 min e empregando o tampão H3BO3/NaOH como solução tampão-suporte na concentração de 0...

Modificação de um micro-extrator de vidro para pré-enriquecimento de traços de pesticidas organoclorados de água para análise por cromatografia gasosa

Rocha,Eduardo Carasek da; Pini,Glaucia Falleiros; Augusto,Fabio; Valente,Antonio Luiz Pires
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/1998 PT
Relevância na Pesquisa
554.1918%
Two models of a glass micro-extractor were constructed after modification of a model proposed in the literature. The two models were used for the simultaneous extraction and enrichment of organochlorinated pesticides from aqueous matrixes to an organic solution appropriate for the gas chromatographic analysis of the pesticide. It was established that the performance of one of the modified micro-extractors permits the pre-concentration of the pesticides to a level that allow their quantitation at the trace level with electron capture detection. It is thus concluded that the glass micro-extractor is a suitable tool for the sample preparation step in the gas chromatographic analysis of environmental pollutants of the class of pesticides.

Flow analysis by using solenoid valves for As(III) determination in natural waters by an on-line separation and pre-concentration system coupled to a tungsten coil atomizer

Neira,José Y.; Mendoza,Jenny; Bruhn,Carlos G.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2005 EN
Relevância na Pesquisa
465.17125%
A flow system coupled to a tungsten coil atomizer in an atomic absorption spectrometer (TCA-AAS) was developed for As(III) determination in waters, by extraction with sodium diethyldithiocarbamate (NaDDTC) as complexing agent, and by sorption of the As(III)-DDTC complex in a micro-column filled with 5 mg C18 reversed phase (10 µL dry sorbent), followed by elution with ethanol. A complete pre-concentration/elution cycle took 208 s, with 30 s sample load time (1.7 mL) and 4 s elution time (71 µL). The interface and software for the synchronous control of two peristaltic pumps (RUN/ STOP), an autosampler arm, seven solenoid valves, one injection valve, the electrothermal atomizer and the spectrometer Read function were constructed. The system was characterized and validated by analytical recovery studies performed both in synthetic solutions and in natural waters. Using a 30 s pre-concentration period, the working curve was linear between 0.25 and 6.0 µg L-1 (r = 0.9976), the retention efficiency was 94±1% (6.0 µg L-1), and the pre-concentration coefficient was 28.9. The characteristic mass was 58 pg, the mean repeatability (expressed as the variation coefficient) was 3.4% (n=5), the detection limit was 0.058 µg L-1 (4.1 pg in 71 µL of eluate injected into the coil)...

Pre-concentration of Cd(II), Cr(III), Cu(II) and Ni(II) on a column packed with free carboxymethylcellulose (CMCH)

Padilha,Pedro de Magalhães; Rocha,Julio Cesar; Campos,Joaquim T.S; Moreira,José Celso; Federici,Cilene C
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/1997 EN
Relevância na Pesquisa
661.526%
Carboxymethylcellulose packed in to a glass column was used to pre-concentrate metallic cations from aqueous solutions. The pre-concentrated metal cations are directly eluted from the column using 5.0 mL of 1.0 mol L-1 hydrochloric acid. The optimum pre-concentration conditions are given (glass column, 16 cm length, 0.80 cm i.d., stationary phase height of 12 cm, flow-rate, 1.5 mL min-1). The recuperation efficiency achieved is greater than 95%, while the enrichment factor is 10 for 50 mL of solution (0.50 mg L-1 each).

Determination of Cu, Ni and Pb in aqueous medium by FAAS after pre-concentration on 2-aminothiazole modified silica gel

Alcântara,Ilton Luiz de; Roldan,Paulo dos Santos; Margionte,Maurício A. L.; Castro,Gustavo R.; Padilha,Cilene C. F.; Florentino,Ariovaldo de Oliveira; Padilha,Pedro de Magalhães
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2004 EN
Relevância na Pesquisa
662.16336%
This work describes the synthesis and characterization of 2-aminothiazole modified silica gel (SiAT), and the results of a study of the adsorption and pre-concentration (in batch and using a flow-injection system coupled to an absorption atomic spectrometer) of Cu(II), Ni(II) and Pb(II) in aqueous medium. The adsorption capacities for each metal ions in mmol g-1 were: Cu(II)= 1.18, Ni(II)= 1.15 and Pb(II)= 1.10. The results obtained in the flow experiments showed a recovery of practically 100% of the metal ions adsorbed in a mini-column packed with 100 mg of SiAT, using 100 µL of 2.0 mol L-1 HCl solution as eluent. The sorption-desorption of the metal ions made possible the application of a flow-injection system for the pre-concentration and quantification by FAAS of metal ions at trace level in natural water samples digested and not digest by an oxidizing UV photolysis.

Flow system for pre-concentration and spectrophotometric determination of reactive mercury

Yonehara,Fernando S.; Pasquini,Celio; Rohwedder,Jarbas J. R.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2005 EN
Relevância na Pesquisa
554.1918%
A new flow system to pre-concentrate and determine reactive mercury in effluents by photometry is presented. The system is based on the reduction of the reactive mercury present in a 500 mL sample with a Sn(II) solution. The reduced mercury is swept out by an argon stream and carried to a straight glass tube (60 cm long, 3 mm i.d.) inclined in an angle of 15º. The inner surface of this tube has been previously covered by a renewable liquid layer of an oxidant solution containing H2O2 (12%, m/v) and HNO3 (3.0 mol L-1) produced after introduction and passage of a liquid monosegment containing those reagents. The swept Hg0 undergoes an oxidative process and the Hg(II) formed is retained in the layer. After a 10 min sweep time interval the argon flow is stopped and a reagent monosegment (350 µL) containing PAR [4-(2-pyridylazo)resorcinol], 1.0 x 10-3 mol L-1, in an ammonia/ ammonium chloride buffer (4.0 mol L-1; pH 9.0) is introduced and passes through the glass tube. A strongly coloured complex between PAR and Hg(II) is formed and carried to the detection system composed of a light emitting diode (LED, lambdamax = 525 nm) and a photodiode detector. Sample processing time is about 12 min. The system is washed and a fresh liquid layer is formed...

Solid sampling analysis by flame atomic absorption spectrometry for lead determination in seawater samples after pre-concentration using cocrystallized alizarin red - naphthalene

Korn,Maria das Graças Andrade; Bispo,Márcia Sousa; Korn,Mauro; Costa,Adilson Ben da; Mattos,Julio Cezar Paz de; Paniz,José Neri Gottfried; Flores,Érico Marlon de Moraes
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2005 EN
Relevância na Pesquisa
554.03906%
A device for direct solid analysis by flame atomic absorption spectrometry (DSA-FAAS) with prior solid phase extraction procedure is proposed for the determination of lead in water samples. A buffer solution (NH4Cl-NH3, pH 8.1) and alizarin red - naphthalene solid phase were added for Pb sorption. After, samples (up to 200 mL) were filtered and the naphthalene matrix was dried, ground to particle size < 80 µm and then maintained into a desiccator up to the Pb determination by DSA-FAAS. Test samples (from 0.1 to 2 mg) were weighed into small polyethylene vials. Vials were connected to a homemade device for solid introduction directly into a conventional air + acetylene flame. Test samples were carried as a dry aerosol to a T-quartz cell specially designed for DSA-FAAS. The T-quartz cell was positioned above the burner and below the optical path of the instrument. In the flame, the generated atomic vapor produced a transient signal that was totally integrated in 2 s. The effect of operating conditions on the analytical signal was evaluated. Background signals were always low (wavelength=217.0 nm) and no memory effects were observed. A characteristic mass of 1.1 ng for Pb was found. Calibration was performed using different masses of solid alizarin red-naphthalene spiked with Pb reference solution. Results were considered satisfactory...

Evaluation of a simple hyphenated system for flow injection solid-phase pre-concentration and capillary electrophoresis

Assunção,Nilson A.; Miranda,Carlos E. S.; Lanças,Fernando M.; Rosias,Maria Fernanda G. G.; Carrilho,Emanuel
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
Relevância na Pesquisa
462.16336%
In this work, the development and evaluation of a hyphenated flow injection-capillary electrophoresis system with on-line pre-concentration is described. Preliminary tests were performed to investigate the influence of flow rates over the analytical signals. Results revealed losses in terms of sensitivity of the FIA-CE system when compared to the conventional CE system. To overcome signal decrease and to make the system more efficient, a lower flow rate was set and an anionic resin column was added to the flow manifold in order to pre-concentrate the analyte. The pre-concentration FIA-CE system presented a sensitivity improvement of about 660% and there was only a small increase of 8% in total peak dispersion. These results have confirmed the great potential of the proposed system for many analytical tasks especially for low concentration samples.

Pre-concentration of lithium prior to its determination in honey by flame optical emission spectrometry

Stecka,Helena; Pohl,Pawel
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
556.4589%
A procedure based on solid phase extraction with a strongly acidic cation-exchanger Dowex 50W×8-200 was proposed to pre-concentrate and determine ultra-traces of Li in different floral honeys. When loading 10% (m/v) honey solutions onto columns packed with the cation-exchanger, Li+ ions were retained on the resin along with K+ and Na+, while simple sugars were passed through columns and were entirely found in effluents. In turn, columns were washed with water and eluted with a 1.0 mol L-1 HCl solution to strip Li+ that was subsequently determined in respective eluates by flame optical emission spectrometry (FOES). The proposed method was characterized by a limit of detection (LOD) of 0.05 ng g-1 of Li and later used for analysis of several raw and commercial mono- and multi-flower honeys. It enabled to determine from 0.4 to 5.3 ng g-1 of Li with precision being within 8-11%. Accuracy of this sample pre-treatment procedure and analysis method was assessed applying spike recovery tests. Recoveries of added Li were found to be within 98 to 106%, demonstrating trustworthiness of results achieved.

Simultaneous determination of Pb and Cd in seafood by ICP OES with on-line pre-concentration by solid phase extraction with amberlite XAD-4 after complex formation with DDTP

Santos,Éder José dos; Santos,Arlene Bispo dos; Herrmann,Amanda Beatriz; Kulik,Suzete; Baika,Loana Mara; Tormen,Luciano; Curtius,Adilson José
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2013 EN
Relevância na Pesquisa
467.03836%
An on-line method for Cd and Pb pre-concentration and simultaneous determination in acid digested seafood by inductively coupled plasma optical emission spectrometry (ICP OES) was developed. The on-line pre-concentration was based on the complex formation of the analytes with the ammonium salt of O,O-diethyldithiophosphate (DDTP) and using the Amberlite XAD-4 resin as a solid support in a homemade column. Different conditions of the flow injection system, such as solutions flow rates, nebulizer pressure and eluent concentration were optimized. Three certified reference materials of lobster hepatopancreas, dogfish liver and fish protein, three samples of fish muscle and three samples of shrimp were digested with HNO3, H2O2 and H2SO4 in a microwave system under reflux. DDTP was added in the solutions obtained, and the mixture was injected in the FI system. Calibration curves for Cd and Pb were obtained using the standard solutions in the concentration range 0.05-0.5 µg mL-1 in the digestion medium, submitted to the same pre-concentration procedure. The quantification limits (3.3 x LOD) for 5 min of pre-concentration time were 0.005 mg kg-1 Cd2+ and 0.1 mg kg-1 Pb2+ in the sample of fish or shrimp in natura, considering 1.0 g of the sample in a final volume of 50 mL. The agreement of the obtained concentrations with the certified ones (Student t-test...

A fully automated flow injection atomic absorption system for the determination of copper traces in waters with on-line pre-concentration in an ion-exchange column

Burguera, J. L.; Burguera, M.; Carrero, P.; Marcano, J.; Rivas, C.; Brunetto, M. R.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em //1995 EN
Relevância na Pesquisa
462.16336%
The paper describes the development of an automatic on-line column pre-concentration technique using a time based-flow injection atomic absorption spectrometry system. A manifold incorporating a micro-column containing 25 mg of Dowex 50W-X8 was used with a time-based injector for the pre-concentration and determination of copper in natural and drinking waters. The system features depend on the alternate positions of a solenoid valve. The 3σ detection limits, enrichment factors, sampling frequency, relative standard deviations and linear calibration graphs were, respectively, in the range 0.6-1.5 μg/l, 25-60, 15-30 measurements/h, 1.0-3.1% and 1-65 μg/ml for pre-concentration times of 1 min. The procedure was successfully applied to a range of water samples and the accuracy was assessed through recovery experiments, the analysis of certified reference water samples and by independent analysis by atomic absorption spectrometry with electrothermal atomization.

Pre-concentration of toxic metals using electrospun amino-functionalized nylon-6 nanofibre sorbent

Darko,Godfred; Sobola,Abdullahi; Adewuyi,Sheriff; Okonkwo,Jonathan Okechukwu; Torto,Nelson
Fonte: South African Journal of Chemistry Publicador: South African Journal of Chemistry
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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This paper presents a new approach for pre-concentrating toxic metals (As, Cd, Ni and Pb) in aqueous environments using an amino-functionalized electrospun nanofibre sorbent. The sorbent, composed of nanofibres of average diameter 80 ± 10 nm and specific surface area of 58 m² g-1, exhibited fast adsorption kinetics (<20 min) for As, Cd, Ni and Pb. The optimal pH for the uptake of As, Cd, Ni and Pb were 5.5, 6.0, 6.5 and 11, respectively. The adsorption process best fitted the Freundlich isotherm and followed the first-order kinetics. The highest pre-concentration achieved using the sorbent was 41.99 (Ni in treated wastewater). The capacity of the sorbent to pre-concentrate the toxic metals was compared with those of aqua regia and HNO3+H2O2 digestions. The pre-concentration factors achieved for Cd in river water samples can be ranked as aqua regia digestion (0.73) > adsorption (0.34) > HNO3+H2O2 (0.23) digestion. A similar trend was observed for Ni in river water as well as Ni and Cd in tap water samples. Pb ions in the river water samples were pre-concentrated slightly better using the two digestion methods (pre-concentration factors ~22) compared to adsorption method (pre-concentration factor ~21). The use of the electrospun amino-functionalized nanofibre sorbentpresents an efficientand cost-effective alternative for pre-concentration of toxic metals in aqueous environments.