Página 1 dos resultados de 230 itens digitais encontrados em 0.037 segundos

Determination of 5-aminosalicylic acid in pharmaceutical formulations by square wave voltammetry at pencil graphite electrodes

ULIANA, Carolina V.; YAMANAKA, Hideko; GARBELLINI, Gustavo S.; SALAZAR-BANDA, Giancarlo R.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
56.49%
An analytical method for the determination of the anti-inflammatory drug 5-aminosalicylic acid (5-ASA) in pharmaceutical formulations using square wave voltammetry at pencil graphite electrodes was developed. After the optimization of the experimental conditions, calibration curves were obtained in the linear concentration range from 9.78 × 10-7 to 7.25 × 10-5 mol L-1 resulting in a limit of detection of 2.12 ± 0.05 x 10-8 mol L-1. Statistical tests showed that the concentrations of 5-ASA in commercial tablets and enemas obtained with the proposed voltammetric method agreed with HPLC values at a 95% confidence level.; CNPq; FAPESP

Disposable Graphite Foil Based Electrodes and Their Application in Pharmaceutical Analysis

OLIVEIRA, Andre G.; MUNOZ, Rodrigo Alejandro A.; ANGNES, Lucio
Fonte: WILEY-V C H VERLAG GMBH Publicador: WILEY-V C H VERLAG GMBH
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.78%
This paper explores a new source of graphite for working electrodes, which presents advantages such as low electrical resistance, good flexibility, favorable mechanical performance, versatility to design electrodes in almost any size and very low cost. The new electrodes were investigated in batch electrochemical cells as associated with flow injection analysis systems. Cyclic voltammetry, stripping voltammetry, and amperometry associated with flow injection analysis techniques were applied for the determination of ascorbic acid, zinc and paracetamol in pharmaceutical formulations, respectively. Well-established analytical methods were applied for comparison purposes. The results herein demonstrate the potential of graphite foils as working electrodes in different electroanalytical methods, offering the possibility of producing disposable sensors for routine applications.; CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP; IM2C (Instituto do Milenio de Materiais Complexos); IM2C (Instituto do Milenio de Materiais Complexos)

Simultaneous voltammetric detection of ascorbic acid, dopamine and uric acid using a pyrolytic graphite electrode modified into dopamine solution

SILVA, Robson P. da; LIMA, Antonio William O.; SERRANO, Silvia H. P.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.31%
Pyrolytic graphite electrodes (PGE) were modified into dopamine solutions using phosphate buffer solutions, pH 10 and 6.5, as supporting electrolyte. The modification process involved a previous anodization of the working electrode at +1. 5 V into 0. 1 mol-L-1 NaOH followed by other anodization step, in the same experimental conditions, into dopamine (DA) solutions. pH of the supporting electrolyte performed an important role in the production of a superficial melanin polymeric film, which permitted the simultaneous detection of ascorbic acid (AA), (DA) and uric acid (UA), Delta EAA-DA = 222 mV-, Delta EAA-UA = 360 mV and Delta EDA-UA=138mV, avoiding the superficial poisoning effects. The calculated detection limits were: 1.4 x 10(-6) mol L-1 for uric acid, 1.3x10-(5) molL(-1) for ascorbic acid and 1.1 X 10(-7) mol L-1 for dopamine, with sensitivities of (7.7 +/- 0.5), (0.061 +/- 0.001) and (9.5 +/- 0.05)A mol(-1) cm(-2), respectively, with no mutual interference. Uric acid was determined in urine, blood and serum human samples after dilution in phosphate buffer and no additional sample pre-treatment was necessary. The concentration of uric acid in urine was higher than the values found in blood and serum and the recovery tests (92-102%) indicated that no matrix effects were observed. (C) 2008 Elsevier B.V. All rights reserved.

"Aplicação de eletrodos compósitos a base de poliuretana-grafite"; "Application of composite electrodes from polyurethane-graphite"

Cervini, Priscila
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 10/10/2006 Português
Relevância na Pesquisa
36.76%
Eletrodos compósitos a base de grafite e resina poliuretana de origem vegetal foram preparados e avaliados quanto ao seu desempenho em relação à determinação voltamétrica e amperométrica de hidroquinona, paracetamol e atenolol. Os eletrodos foram preparados sob pressões diferentes em prensa hidráulica, demonstrando que quanto maior a pressão, maior a corrente medida para uma mesma solução, até um valor limite. O ferricianeto de potássio foi usado como sonda eletroquímica para testes de desempenho do eletrodo em voltametria de onda quadrada (SWV) e por análise em fluxo (FIA), com detecção amperométrica com o eletrodo compósito 60% (grafite, m/m) como eletrodo de trabalho. A hidroquinona (HQ) foi determinada em SWV e FIA, com limites de detecção (LD) da ordem de 283 nmol L-1 e 100 ?mol L-1, respectivamente. A determinação de HQ em reveladores fotográficos forneceu resultados que concordam com o método de comparação em cromatografia líquida de alta eficiência (HPLC) com 95% de confiança. Determinação de paracetamol (APAP) em voltametria de pulso diferencial (DPV), eletrodo de disco rotatório (RDE), FIA e cronoamperometria levaram a limites de detecção de 3,9; 2,6; 18,9 e 6,7 ?mol L-1, respectivamente...

Grafite funcionalizada em condições de Friedel-Crafts mediada por radiação de microondas: novo material para construção de eletrodos de pasta de carbono; Graphite Functionalized in Conditions of Friedel-Crafts Reaction mediated by Radiation of Microwave: New Material for Construction of Electrodes of Carbon Paste

Nascimento, Leandro Fontanetti do
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 16/03/2007 Português
Relevância na Pesquisa
36.78%
A modificação e/ou a funcionalização de eletrodos têm por objetivos o desenvolvimento de métodos eficazes para a preparação de eletrodos quimicamente modificados (EQMs) que possam aliar melhorias em sua sensibilidade, seletividade e reatividade em relação aos eletrodos base. Entretanto, a estabilidade e a reprodutibilidade dos EQMs quanto ao processo de lixiviação dos modificadores precisam ser melhorados para que se possam obter eletrodos mais robustos com longo tempo de análise. Uma das possibilidades para se obter eletrodos mais estáveis é por meio de uma ligação estável do tipo covalente entre o eletrodo base e o modificador. Desta forma este trabalho tem por objetivo a funcionalização da grafite por meio de uma reação covalente entre os modificadores cloreto de 4-nitrobenzoíla (4-NB), cloreto de 3,4-dihidroxibenzoíla (3,4-DHB) e do cloreto de 2,2?-bipiridina 4,4?-dicarbonílico (2,2-BP) por meio de uma reação de acilação de Friedel-Crafts assistida por radiação de microondas. O material de síntese foi caracterizado por voltametria cíclica, espectroscopia de infravermelho, curvas termogravimétricas e térmicas diferenciais e espectroscopia de impedância eletroquímica em comparação com a mistura física entre a grafite e os modificadores. Além disso...

Desenvolvimento e aplicação de eletrodos compósitos à base de grafite e Araldite®; Development and apllication of composite electrode graphite-Araldite®

Calixto, Carolina Maria Fioramonti
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 11/07/2008 Português
Relevância na Pesquisa
36.75%
A confecção e avaliação do desempenho voltamétrico de eletrodos compósitos à base de resina epóxi comercial Araldite ® utilizada como fase aglutinante e pó de grafite como fase condutora, na confecção dos eletrodos compósitos foi realizada. A resina foi preparada seguindo instruções do fabricante e adicionada a uma quantidade de pó de grafite para obter eletrodos contendo 50, 60 e 70% de grafite (m/m). Tais compósitos foram caracterizados fisicamente quanto à reprodutibilidade da resposta voltamétrica, resistência ôhmica e área efetiva em função da composição grafite/Araldite ®, sendo 70% (grafite, m/m) a que ofereceu melhores resultados, em termos de repetibilidade de resposta e corrente de pico. O teor real de grafite foi determinado por termogravimetria. Os intervalos úteis de potenciais para uso dos eletrodos compósitos também foram avaliados em diferentes eletrólitos. Finalmente, os eletrodos compósitos foram avaliados na determinação de atenolol, uma droga antihipertensiva, e dopamina, um neurotransmissor central do grupo das catecolaminas. Em todos os casos, o eletrodo compósito foi mais sensível na determinação dos dois analitos, quando comparado ao eletrodo de carbono vítreo. A dopamina foi determinada por voltametria de pulso diferencial (DPV). O limite de detecção foi de 0...

Determination of 5-aminosalicylic acid in pharmaceutical formulations by square wave voltammetry at pencil graphite electrodes

Uliana, Carolina V.; Yamanaka, Hideko; Garbellini, Gustavo S.; Salazar-Banda, Giancarlo R.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: 964-967
Português
Relevância na Pesquisa
56.49%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 06/50692-2; An analytical method for the determination of the anti-inflammatory drug 5-aminosalicylic acid (5-ASA) in pharmaceutical formulations using square wave voltammetry at pencil graphite electrodes was developed. After the optimization of the experimental conditions, calibration curves were obtained in the linear concentration range from 9.78 × 10-7 to 7.25 × 10-5 mol L-1 resulting in a limit of detection of 2.12 ± 0.05 x 10-8 mol L-1. Statistical tests showed that the concentrations of 5-ASA in commercial tablets and enemas obtained with the proposed voltammetric method agreed with HPLC values at a 95% confidence level.

Kinetics of direct and substrate-mediated electron transfer of versatile peroxidase-modified graphite electrodes

Munteanu, Florentina-Daniela; Ruiz-Duenas, Francisco J.; T. Martinez, Angel; Paulo, Artur Cavaco
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2005 Português
Relevância na Pesquisa
56.65%
Electron transfer (ET) of versatile peroxidase (VP) was studied in the bioelectrocatalytic reduction reaction of H2O2 at peroxidase- modified graphite electrodes to obtain additional information on the kinetic characteristics of this novel ligninolytic peroxidase. Rotating disk electrodes (RDE) experiments were performed at 0 V (vs. SCE) in two different buffers (tartrate buffer, pH 5.0; and citrate buffer, pH 3.0). From measurements of the mediated and mediatorless currents of H2O2 reduction at the RDE, the percentage of VP molecules involved in direct ET (?55%) was calculated. The peroxidase-modified electrodes were used for determination of the donor substrates in RDE mode, and the results were interpreted in terms of catalytic efficiencies.

Eletrólise da água para produção de gás de síntese

Guerra, Luís Filipe Sanches
Tipo: info:eu-repo/semantics/masterthesis
Publicado em /01/2015 Português
Relevância na Pesquisa
46.39%
As necessidades energéticas em todo o globo têm vindo a aumentar ao longo da sua história. As últimas décadas foram marcadas pelo aumento do consumo de fontes de energia primária, onde as fontes renováveis têm sido continuamente mais consumidas. Para comprovar esta tendência, o consumo de energias renováveis em Portugal já representa cerca de 20 % do consumo de energia primária. O presente trabalho consiste na produção de gás de síntese a partir da eletrólise da água, utilizando elétrodos de grafite e uma solução alcalina como eletrólito. Deste modo, neste trabalho de investigação estudou-se o comportamento e respetiva otimização de diversos parâmetros, como a concentração e natureza do eletrólito, a temperatura inicial de ensaio e a tensão aplicada ao eletrolisador, tendo por base a avaliação dos principais outputs do processo, como é o caso do teor em monóxido de carbono e oxigénio, a percentagem de conversão de carbono em espécies gasosas carbonadas e o caudal de gases produzido. Os resultados mais favoráveis foram obtidos ao se utilizar hidróxido de sódio como eletrólito, a uma concentração de 0,4 M, uma temperatura inicial de ensaio de 35 ?C e uma tensão aplicada de 5 V. Deste modo...

Artefacts induced on c-type haem proteins by electrode surfaces

Sousa, Patrícia M. Paes de; Pauleta, Sofia R.; Gonçalves, M. Lurdes Simões; Pettigrew, Graham W.; Moura, Isabel; Moura, José J. G.; Santos, Margarida M. Correia dos
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
46.65%
J Biol Inorg Chem (2011) 16:209–215 DOI 10.1007/s00775-010-0717-z; In this work it is demonstrated that the characterization of c-type haem containing proteins by electrochemical techniques needs to be cautiously performed when using pyrolytic graphite electrodes. An altered form of the cytochromes, which has a redox potential 300 mV lower than that of the native state and displays peroxidatic activity, can be induced by interaction with the pyrolytic graphite electrode. Proper control experiments need to be performed, as altered conformations of the enzymes containing c-type haems can show activity towards the enzyme substrate. The work was focused on the study of the activation mechanism and catalytic activity of cytochrome c peroxidase from Paracoccus pantotrophus. The results could only be interpreted with the assignment of the observed non-turnover and catalytic signals to a non-native conformation state of the electron-transferring haem. The same phenomenon was detected for Met–His monohaem cytochromes (mitochondrial cytochrome c and Desulfovibrio vulgaris cytochrome c-553), as well as for the bis-His multihaem cytochrome c 3 from Desulfovibrio gigas, showing that this effect is independent of the axial coordination of the c-type haem protein. Thus...

Determination of 5-aminosalicylic acid in pharmaceutical formulations by square wave voltammetry at pencil graphite electrodes

Uliana,Carolina V.; Yamanaka,Hideko; Garbellini,Gustavo S.; Salazar-Banda,Giancarlo R.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 Português
Relevância na Pesquisa
56.49%
An analytical method for the determination of the anti-inflammatory drug 5-aminosalicylic acid (5-ASA) in pharmaceutical formulations using square wave voltammetry at pencil graphite electrodes was developed. After the optimization of the experimental conditions, calibration curves were obtained in the linear concentration range from 9.78 × 10-7 to 7.25 × 10-5 mol L-1 resulting in a limit of detection of 2.12 ± 0.05 x 10-8 mol L-1. Statistical tests showed that the concentrations of 5-ASA in commercial tablets and enemas obtained with the proposed voltammetric method agreed with HPLC values at a 95% confidence level.

Development of a DC-plasma torch constructed with graphite electrodes and an integrated nebulization system for decomposition of CCl4

Cubas,Anelise L.V.; Carasek,Eduardo; Debacher,Nito A.; Souza,Ivan G. de
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 Português
Relevância na Pesquisa
46.39%
This work describes the development of a continuous flow plasma torch with graphite electrodes and an integrated nebulization system for the elimination of organochlorine liquid waste (carbon tetrachloride) on a small scale. The gases resulting from the pyrolysis of the carbon tetrachloride by the plasma were collected and identified by gas chromatography, coupled with mass spectrometry (GC-MS). Monitoring was carried out by gas chromotography with flame ionization detection (GC-FID). It was observed that the thermal plasma technique eliminated the carbon tetrachloride completely, being characterized by low cost, operational simplicity and reduced dimensions. This technique presents a suitable environmentally correct alternative, since it reduces the total emission of organochlorine gases.

A Biosensor Using Poly(4-Aminophenol)/acetylcholinesterase modified graphite electrode for the detection of dichlorvos

Melo,Edmar Isaías; Franco,Diego Leoni; Afonso,André Santiago; Rezende,Hélen Cristine; Brito-Madurro,Ana Graci; Madurro,João Marcos; Coelho,Nívia Maria Melo
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 Português
Relevância na Pesquisa
46.42%
The properties of poly(4-aminophenol) modified graphite electrode as material for the immobilization of acetylcholinesterase were investigated by the Cyclic Voltammetry, Electrochemical Impedance Spectroscopy and Atomic Force Microscopy. The polymer was deposited on graphite electrode surface by the oxidation of 4-aminophenol and then acetylcholinesterase was immobilized on the surface of the electrode. The biosensor coupled in the continuous flow system was employed for the detection of dichlorvos. The detection and quantification limits were 0.8 and 2.4 ?mol L-1 dichlorvos, respectively. Graphite electrodes modified with the poly(4-aminophenol) showed to be an efficient and promising material for immobilization of acetylcholinesterase enzyme. The proposed method requires simple parts which are easy to build, involves only one biosensor and the potentiometric detection is simple.

The behavior of graphite and copper electrodes on the finish die-sinking electrical discharge machining (EDM) of AISI P20 tool steel

Amorim,Fred L.; Weingaertner,Walter L.
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 Português
Relevância na Pesquisa
46.83%
The machining parameter settings installed at CNC EDM machines are developed under optimum process conditions. Standard workpiece and electrode materials are used traditionally by machine manufacturers to establish the EDM parameter settings. However, this is not the usual situation of the tooling industry, where many different grades of workpiece and tool electrode materials are used. Consequently, the customers are required to develop their own process parameters, which normally demand many experimental tests. According to the aforementioned argument an experimental investigation on the EDM of AISI P20 tool steel under finish machining has been carried out. The tests were performed with graphite and copper as tool electrodes. Important EDM electrical parameters that influence the process performance were investigated. The measured technological outputs were the material removal rate Vw, volumetric relative wear J and workpiece surface finish Ra . The main conclusions can be summarized as follows: the best results for material removal rate Vw were reached when EDM with negative graphite electrodes. Graphite and copper tools presented similar results of Vw for positive polarity. For graphite and copper tools the lowest values of volumetric relative wear were achieved for positive polarity. The best surface roughness Ra was obtained for copper electrodes under negative polarity.

A membrane-less enzymatic fuel cell with layer-by-layer assembly of redox polymer and enzyme over graphite electrodes†

Rengaraj, Saravanan; Mani, Vigneshwaran; Kavanagh, Paul; Rusling, James; Leech, Dónal
Tipo: text
Português
Relevância na Pesquisa
46.39%
Layer-by-layer (LBL) assembly of alternate osmium redox polymers and glucose oxidase, at anode, and laccase, at cathode, using graphite electrodes form a membrane-less glucose/O2 enzymatic fuel cell providing a power density of 103 ?W cm?2 at pH 5.5.

Effect of applied voltage, initial concentration and natural organic matter on sequential reduction/oxidation of nitrobenzene by graphite electrodes

Sun, Mei; Reible, Danny D.; Lowry, Gregory V.; Gregory, Kelvin B.
Tipo: text
Português
Relevância na Pesquisa
46.59%
Carbon electrodes are proposed in reactive sediment caps for in situ treatment of contaminants. The electrodes produce reducing conditions and H2 at the cathode and oxidizing conditions and O2 at the anode. Emplaced perpendicular to seepage flow, the electrodes provide the opportunity for sequential reduction and oxidation of contaminants. The objectives of this study are to demonstrate degradation of nitrobenzene (NB) as a probe compound for sequential electrochemical reduction and oxidation, and to determine the effect of applied voltage, initial concentration and natural organic matter on the degradation rate. In H-cell reactors with graphite electrodes and buffer solution, NB was reduced stoichiometrically to aniline (AN) at the cathode with nitrosobenzene (NSB) as the intermediate. AN was then removed at the anode, faster than the reduction step. No common AN oxidation intermediate was detected in the system. Both the first order reduction rate constants of NB (kNB) and NSB (kNSB) increased with applied voltage between 2V and 3.5 V (when the initial NB concentration was 100 µM, kNB=0.3 d?1 and kNSB=0.04 d?1at 2V; kNB=1.6 d?1 and kNSB=0.64 d?1at 3.5 V) but stopped increasing beyond the threshold of 3.5V. When initial NB concentration decreased from 100 to 5 µM...

Specific and Reversible Immobilization of Proteins Tagged to the Affinity Polypeptide C-LytA on Functionalized Graphite Electrodes

Bello-Gil, Daniel; Maestro, Beatriz; Fonseca, Jennifer; Feliu, Juan M.; Climent, Víctor; Sanz, Jesús M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: text
Publicado em 31/01/2014 Português
Relevância na Pesquisa
46.65%
We have developed a general method for the specific and reversible immobilization of proteins fused to the choline-binding module C-LytA on functionalized graphite electrodes. Graphite electrode surfaces were modified by diazonium chemistry to introduce carboxylic groups that were subsequently used to anchor mixed self-assembled monolayers consisting of N,N-diethylethylenediamine groups, acting as choline analogs, and ethanolamine groups as spacers. The ability of the prepared electrodes to specifically bind C-LytA-tagged recombinant proteins was tested with a C-LytA-?-galactosidase fusion protein. The binding, activity and stability of the immobilized protein was evaluated by electrochemically monitoring the formation of an electroactive product in the enzymatic hydrolysis of the synthetic substrate 4-aminophenyl ?-D-galactopyranoside. The hybrid protein was immobilized in an specific and reversible way, while retaining the catalytic activity. Moreover, these functionalized electrodes were shown to be highly stable and reusable. The method developed here can be envisaged as a general, immobilization procedure on the protein biosensor field.

Investigations on the use of graphite electrodes using a Hull-type growth cell for the electrochemically-assisted protein crystallization

Espinoza-Montero, Patricio J.; Moreno-Narváez, María Esther; Frontana-Uribe, Bernardo A.; Stojanoff, Vivian; Moreno, Abel
Tipo: text
Português
Relevância na Pesquisa
46.85%
This paper describes the use of an electrochemical Hull type cell adapted for protein crystallization evaluating three inclination angles (45°, 60° and 90°). For optimization experiments, classical platinum wire electrodes were used and once the best geometry was known, they were replaced with 0.5 mm diameter low-cost graphite automatic pencil leads. Using Pt and graphite, the cell with electrodes fitted at 90° showed the most favorable geometry for promoting the growth of lysozyme crystals with enough size for protein crystallography (between 200–250 ?m in solution, and between 500–650 ?m in gel). The crystalline quality (mosaicity and I/?(I) ratio) of crystals obtained at different current values, was studied using these graphite electrodes and was compared with those protein crystals grown using platinum wire electrodes in solution as well as in gel experiments. These studies showed that it is possible to efficiently substitute the platinum electrodes by the low-cost graphite electrodes. This cell could be a first approach to a disposable cell for a large-scale use of electrochemically-assisted crystal growth method.

Real-time monitoring of subsurface microbial metabolism with graphite electrodes

Wardman, Colin; Nevin, Kelly P.; Lovley, Derek R.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: text
Publicado em 21/11/2014 Português
Relevância na Pesquisa
46.6%
Monitoring in situ microbial activity in anoxic submerged soils and aquatic sediments can be labor intensive and technically difficult, especially in dynamic environments in which a record of changes in microbial activity over time is desired. Microbial fuel cell concepts have previously been adapted to detect changes in the availability of relatively high concentrations of organic compounds in waste water but, in most soils and sediments, rates of microbial activity are not linked to the concentrations of labile substrates, but rather to the turnover rates of the substrate pools with steady state concentrations in the nM–?M range. In order to determine whether levels of current produced at a graphite anode would correspond to the rates of microbial metabolism in anoxic sediments, small graphite anodes were inserted in sediment cores and connected to graphite brush cathodes in the overlying water. Currents produced were compared with the rates of [2-14C]-acetate metabolism. There was a direct correlation between current production and the rate that [2-14C]-acetate was metabolized to 14CO2 and 14CH4 in sediments in which Fe(III) reduction, sulfate reduction, or methane production was the predominant terminal electron-accepting process. At comparable acetate turnover rates...