The determination of p-cresol in chloroform with an enzyme electrode used in the organic phase

Hall, Geoffrey F.; Best, D. J.; Turner, Anthony P. F.

doi:10.1016/s0003-2670(00)81345-8

Cited by 148 publications

(42 citation statements)

References 11 publications

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“…The ability of enzymes to operate in organic solvents has led to the development of organic-phase enzyme electrodes (OPEEs), capable of working in highly non-polar solvents through to mixed water-miscible solvent/buffer [75][76][77][78][79][80][81]. The operational benefits of such devices include stability, simpler immobilisation techniques, suppression of undesirable side reactions and increased operating range [75].…”

Section: Enzymes and Enzyme Electrochemistry In The Organic-phasementioning

confidence: 99%

Organic phase immunosensors

Setford¹,

Kröger²,

Turner³

1999

Analusis

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Many analytical methods involving non-polar analytes require solvent extraction prior to measurement. The analysis procedure is greatly simplified if the method is able to function effectively in the more non-polar solvent extract. This consideration, coupled with the increasing need for simple, specific and rapid diagnostic and screening tools, has focused interest in the development of organic-phase immunosensors.

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Section: Enzymes and Enzyme Electrochemistry In The Organic-phasementioning

confidence: 99%

Organic phase immunosensors

Setford¹,

Kröger²,

Turner³

1999

Analusis

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“…10 In addition to purified enzymes, [11][12][13] animal, 14 and vegetable extracts, [15][16][17][18] immobilized on the electrode surface by different methods, have also been employed as catalyst sources in both aqueous and organic solutions. Carbon paste electrodes have been widely used owing to the possibility of immobilizing not only enzymes, but also ligands, redox mediators, biological tissues, to catalyze the oxidation/reduction of compounds involved in enzymatic reaction.…”

Section: Introductionmentioning

confidence: 99%

Determination of catecholamines in pharmaceutical formulations using a biosensor modified with a crude extract of fungi laccase (Pleurotus ostreatus)

Leite¹,

Fatibello‐Filho²,

Barbosa-Dekker³

2003

J. Braz. Chem. Soc.

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Um biossensor de pasta de carbono modificado com extrato bruto enzimático do fungo Pleurotus ostreatus como fonte de lacase é proposto para a determinação de catecolaminas em formulações farmacêuticas. Essa enzima catalisa a oxidação de adrenalina ou dopamina nas quinonas correspondentes e a corrente obtida na redução eletroquímica de cada um dos produtos é relacionada a concentração dessas catecolaminas em solução da amostra. O efeito da concentração de lacase de 0,29 a 1,8 U/mg de pasta de carbono, do pH de 3,0 a 8,0, da velocidade de varredura de 10 a 40 mV s -1 e amplitudes de pulso de potencial de 10 a 60 mV sobre a resposta voltamétrica de pulso diferencial foi investigado. O desvio padrão relativo foi menor que 1,8% para solução de hidroquinona 2,8 x 10 -4 mol L -1 em pH 7 (n=10). Recuperações variando de 97,3 a 101% para adrenalina e de 95,8 a 102% para dopamina foram obtidas. As curvas analíticas foram lineares no intervalo de concentração de adrenalina de 6,0 x 10 -5 a 7,0 x 10 -4 mol L -1 e de 7,0 x 10 -5 a 4,0 x 10 -4 mol L -1 para dopamina, com limites de detecção de 7,9 x 10 -6 mol L -1 e 9,8 x 10 -6 mol L -1 , respectivamente. Esse biossensor foi empregado para a determinação de adrenalina e dopamina em formulações farmacêuticas. Os resultados obtidos com o biossensor para a determinação dessas catecolaminas em formulações farmacêuticas estão em concordância a um nível de confiança de 95% com o procedimento da Farmacopéia americana.A carbon paste biosensor modified with a crude enzymatic extract of the Pleurotus ostreatus fungi as a laccase source is proposed for catecholamine determination in pharmaceutical formulations. This enzyme catalyzes the oxidation of adrenaline or dopamine in the corresponding quinones and the current obtained in the electrochemical reduction of each of the products is related to the concentration of these catecholamines in the sample solution. The effect of the laccase concentration from 0.29 to 1.8 U/mg of carbon paste, pH from 3.0 to 8.0, scan rate from 10 to 40 mV s -1 and potential pulse amplitude from 10 to 60 mV on the differential pulse voltammetric response was investigated. The relative standard deviation was smaller than 1.8% for a 2.8 x 10 -4 mol L -1 hydroquinone solution at pH 7.0 (n=10). Recoveries varied from 97.3 to 101% for adrenaline and from 95.8 to 102% for dopamine. The analytical curves were rectilinear in the adrenaline concentration range from 6.0 x 10 -5 to 7.0 x 10 -4 mol L -1 and 7.0 x 10 -5 to 4.0 x 10 -4 mol L -1 for dopamine, with detection limits of 7.9 x 10 -6 mol L -1 and 9.8 x 10 -6 mol L -1 , respectively. This biosensor was used for adrenaline and dopamine determinations in pharmaceutical formulations. The results obtained using the proposed biosensor are in close agreement with those obtained using an American Pharmacopoeia procedure at a 95% confidence level. Keywords: laccase, Pleurotus ostreatus, catecholamines, biosensor IntroductionCatecholamines play an important role in the central nervous system as neurotransmitters. They als...

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“…Os esforços para usar tirosinase como uma ferramenta analítica para a determinação de fenóis e catecóis com transdução eletroquímica iniciaram em 1977 com o trabalho de Macholan e Schanel 58 . Desde então, muitos biossensores baseados em tirosinase têm sido elaborados para a determinação de fenol envolvendo várias formas de detecção eletroquímica: detecção do consumo de oxigênio [58][59][60] , redução direta da o-quinona gerada [34][35][61][62][63][64][65][66][67][68][69][70][71] e redução mediada da o-quinona 72, 73 . O princípio da detecção do consumo de oxigênio está baseado no eletrodo de oxigênio de Clark, ao qual é incorporado um biocatalisador que utiliza oxigênio na presença de um substrato específico 74 .…”

Section: Biossensores a Base De Tirosinaseunclassified