Dual amperometric biosensor device for analysis of binary mixtures of phenols by multivariate calibration using partial least squares (original) (raw)
Related papers
Journal of the Brazilian Chemical Society
Phenolic compounds are important environmental contaminants due to their high toxicity and persistence in the environment. The use of enzyme-based electrochemical biosensors is a simple, sensitive and low-cost alternative for the determination of these pollutants in contaminated waters. However, in most cases, it is impossible to detect specific compounds in a mixture of phenols due to signal-overlap, as the instruments operate at very close potentials, given that the system is based on a single enzyme to detect similar structures. In order to overcome this problem, in the present work we have successfully used multivariate calibration with partial least squares (PLS) for the simultaneous determination of hydroquinone and guaiacol by a tyrosinase-based biosensor that was assembled using an enzyme extract from yam. The use of PLS allowed us to work with a large number of voltammograms, leading to a single mathematical model for the simultaneous determination of phenols of similar structure in real samples with concentration values of mmol L-1 .
Phenols monitoring and Hill coefficient evaluation using tyrosinase-based amperometric biosensors
Bioelectrochemistry, 2004
Sensitive amperometric biosensors for phenols compounds, based on tyrosinase (polyphenoloxidase, PPO) immobilized on a Pt electrode in an electropolymerized poly-amphiphilic pyrrole matrix or cross-linked with glutaraldehyde, were constructed and compared. Steady-state amperometric measurements, performed at À 50 mV vs. SCE in aqueous phosphate buffer containing LiClO 4 0.1 M (pH 7) as well as in a chloroform solution containing 0.1 M C 6 H 5 CH 2 N(CH 3 ) 3 Cl, were used in order to compare the electroanalytical and kinetic parameters of the investigated amperometric biosensors in aqueous and nonaqueous media. It was established that the polypyrrole matrix has a higher efficiency for enzyme retention resulting in higher bioelectrode sensitivity, both in aqueous buffer (690 AA M À 1 ) and in chloroform (149 AA M À 1 ).
Amperometric biosensors precision improvement. Application to phenolic pollutants determination
Electrochimica Acta, 2014
Electrodes fouling associated with the electroenzymatic phenols determination was characterized in this work, applying various techniques such as cyclic voltammetry, amperometry, EQCM, and optical microscopy. An approach to overcome the fouling effects and hence to improve the precision of the phenolic compounds determination was suggested and tested. This approach consists of pulsed potential waveform application with a cleaning potential step of + 1.4 V vs. Ag, AgCl/KCl sat with a duration of 166.66 ms, while the determination was carried out at 0.0 V vs. Ag, AgCl/KCl sat applied for 66.64 ms. As a result a RSD of 2.97% for 0.6 mmol L À1 o-catechol determination was achieved, compared with 6.53% without the cleaning step application. The method was successfully used for the precise phenolic and triazine pollutants determination.
2005
The determination of phenolic compounds is significant given its toxicity, even at very low concentration levels. Amperometric determination of phenols is a simple technique available. Direct oxidation of phenols can be used, but another possibility is the use of polyphenol oxidase (tyrosinase) enzyme biosensors that oxidises the phenolic compounds into their corresponding quinones. Reduction of the resulting quinones accomplishes the amplification of the amperometric signal, as long as the result of the reduction process is the corresponding cathecol, this being able to be oxidised again by the polyphenol oxidase immobilized on the surface of the biosensor. In this communication, simultaneous determination of different phenols was carried out combining biosensor measurements with chemometric tools, in what is known as electronic tongue. The departure information used was the overlapped reduction voltammogram generated with the amperometric biosensor based on polyphenol oxidase. Artificial Neural Networks (ANN) were used for extraction and quantification of each compound. Phenol, cathecol and m-cresol formed the three-analyte study case resolved in this work. Good prediction ability was attained, and so, the separate quantification of these three phenols was accomplished.
Biosensors for phenol derivatives using biochemical signal amplification
Talanta, 2003
Two different approaches, both exploiting two enzymes cooperative functioning, to enhance the sensitivity of tyrosinase (PPO) based biosensor for amperometric detection of phenols have been compared. For this purpose, one monoenzyme electrode (PPO) and two bienzyme electrodes (PPO and d-glucose dehydrogenase, GDH; PPO and horseradish peroxidase, HRP) were constructed using agar-agar gel as enzyme immobilization matrix. The biosensors responses for l-tyrosine detection were recorded at -50 mV versus saturated calomel electrode (SCE). The highest sensitivity (74 mA M(-1)) was observed for the PPO-GDH couple, while that recorded for PPO-HRP couple system was only 32 times higher than that measured for monoenzyme electrode (0.01 mA M(-1)). The ability of the PPO-, PPO-GDH-, PPO-HRP-based biosensors to assay phenols was demonstrated by quantitative determination of phenol, 1,2-dihydroxybenzene, 1,3-dihydroxybenzene, 1,4-dihydroxybenzene, 2-amino-3 (4-hydroxyphenyl) propanoic acid, 2-hydroxytoluene, 3-hydroxytoluene, 4-hydroxytoluene, 4-clorophenol, 3-clorophenol, 2-clorophenol, 4-hydroxybenzoic acid.
Composite Multienzyme Amperometric Biosensors for an Improved Detection of Phenolic Compounds
Electroanalysis, 2003
A biosensor design, in which glucose oxidase and peroxidase are coimmobilized by simple physical inclusion into the bulk of graphite-Teflon pellets, is reported for the detection of phenolic compounds. This design allows the ™in situ∫ generation of the H 2 O 2 needed for the enzyme reaction with the phenolic compounds, which avoids several problems detected in the performance of single peroxidase biosensors as a consequence of the presence of a high H 2 O 2 concentration. So, a much lower surface fouling was found at the GOD-HRP biosensor in comparison with a graphite-Teflon-HRP electrode, suggesting that the controlled generation of H 2 O 2 makes more difficult the formation of polymers from the enzyme reaction products. The construction of trienzyme biosensors, in which GOD, HRP and tyrosinase were coimmobilized into the graphite-Teflon matrix is also reported, and their performance was compared with that of GOD-HRP bienzyme electrodes. The practical applicability of the composite multienzyme amperometric biosensors was evaluated by the estimation of the phenolic compounds content in waste waters from a refinery, and the results were compared with those obtained by using a colorimetric official method based on the reaction with 4aminoantipyrine.
Electrochemical biosensor-based devices for continuous phenols monitoring in environmental matrices
Journal of the Brazilian Chemical Society, 2002
Desenvolveu-se um método de análise em fluxo para a determinação contínua de compostos fenólicos em matrizes ambientais, usando-se uma membrana de diálise para amostragem e biossensores a base de lacase e tirosinase para a detecção destes compostos. A resposta dos biossensores frente a diferentes compostos fenólicos foi investigada. O biossensor a base de lacase mostrou uma alta sensibilidade para guaiacol e cloroguaiacol, enquanto que o biossensor de tirosinase foi mais sensível para fenol e clorofenol. Ambos os biossensores apresentaram respostas seletivas para concentrações destes compostos em níveis micromolares. Limites de detecção de 1,1 x 10-7 mol L-1 para guaiacol e de 1,9 x 10-7 mol L-1 para cloroguaiacol foram obtidos usando-se o biossensor a base de lacase. Empregando-se o biossensor a base de tirosinase obteve-se limites de detecção de 1,5 x 10-7 mol L-1 para fenol e de 9,0 x 10-8 mol L-1 para clorofenol. O método de análise em fluxo proposto apresentou um faixa linear de trabalho entre 1,0 mmol L-1 e 100,0 mmol L-1 , nas condições operacionais otimizadas dos biossensores (biossensor a base de lacase: pH 5,0 e potencial de trabalho 0 mV vs Ag/AgCl; biossensor a base de tirosinase: pH 5,0 e potencial de trabalho 50 mV vs Ag/AgCl). Uma amostra real de efluente papeleiro foi analisada pelo sistema proposto e pelo método colorimétrico de referência e os resultados discutidos. A flow system method for continuous determination of phenolic compounds in environmental matrices was employed using a dialysis membrane sampler and laccase-and tyrosinase-based biosensors as detector. The biosensors response to different phenolic compounds was investigated. The laccase-based biosensor showed high sensitivity to guaiacol and chloroguaiacol, while the tyrosinase-based biosensor was more sensitive to phenol and chlorophenol. Both of the biosensors presented highly selective measurements of micromolar concentration of these compounds. Detection limits around 1.1 x 10-7 mol L-1 for guaiacol and 1.9 x 10-7 mol L-1 for chloroguaiacol could be estimated for the laccase-based biosensor. Using the tyrosinase-based biosensor detection limits of 1.5 x 10-7 mol L-1 for phenol and 9.0 x 10-8 mol L-1 for chlorophenol were observed. The proposed flow method presented a linear response range between 1.0 mmol L-1 and 100.0 mmol L-1 , in the optimized operational conditions (laccase-based biosensor: pH 5.0 and 0 mV vs Ag/AgCl as working potential; tyrosinase-based biosensor: pH 5.5 and 50 mV vs Ag/AgCl as working potential). Real paper mill effluent sample was analyzed by this system and by the reference colorimetric method and the results were discussed.
2002
An electrochemical biosensor for remote continuous monitoring of phenolic compounds in environmental analysis is described. The probe relies on rapid and sensitive amperometric detection at a submersible biosensor assembly, connected to a 50 ft long shielded cable. The enzymes laccase and tyrosinase were used as individual sensors and also as a bienzymatic sensor; these enzymes were immobilized chemically on the carbon fiber transducer. The analysis was based on the amperometric detection of the enzymatic products at a potential of 20.10 V vs. Ag/AgCl. Operational conditions were optimized to meet the requirements of remote operations. Tests with untreated river water spiked with phenolic compounds gave results similar to those obtained with synthetic buffer solutions. The remote laccase biosensor allowed the convenient quantification of guaiacol and chloroguaiacol at levels down to 22 and 9 nmol L 21 , respectively. The co-immobilization of laccase and tyrosinase allowed the efficient detection of a larger group of phenolic compounds.
Disposable tyrosinase-peroxidase bi-enzyme sensor for amperometric detection of phenols
Biosensors and Bioelectronics, 2002
A new disposable amperometric bi-enzyme sensor system for detecting phenols has been developed. The phenol sensor developed uses horseradish peroxidase modified screen-printed carbon electrodes (HRP-SPCEs) coupled with immobilized tyrosinase prepared using poly(carbamoylsulfonate) (PCS) hydrogels or a poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) matrix. Optimization of the experimental parameters has been performed with regard to buffer composition, pH, operating potential and storage stability. A cooperative reaction involving tyrosinase and HRP occurs at a potential of (/50 mV versus Ag/AgCl without the requirement for addition of extraneous H 2 O 2 , thus, resulting in a very simple and efficient system. Comparison of the electrode responses with the 4-aminoantipyrine standard method for phenol sample analysis indicated the feasibility of the disposable sensor system for sensitive 'in-field' determination of phenols. The most sensitive system was the tyrosinase immobilized HRP-SPCE using PCS, which displayed detection limits for phenolic compounds in the lower nanomolar range e.g. 2.5 nM phenol, 10 nM catechol and 5 nM p-cresol.
Sensor Letters, 2010
A new polymeric matrix, the copolymer of 3-thienylmethyl methacrylate (MTM) and glycidyl methacrylate (GMA), was used to develop a phenol biosensor based on laccase (TvLac). Chemical immobilization of the enzyme, TvLac, was achieved via the epoxy moiety of GMA onto the GMA-co-MTM coated glassy carbon electrode. GC/(GMA-co-MTM)/TvLac working electrode was investigated for the parameters of linear range, sensitivity, stability, pH and detection limit. Amperometric response was measured as a function of concentration of phenolic compounds, at a fixed bias voltage of −200 mV. The sensitivity in the linear range increased in this order with the GC/(GMA-co-MTM)/TvLac: 3-Chlorophenol > 2-Chlorophenol > 2,6-Dimethoxyphenol > Catechol > 4Methoxyphenol > 4-Chlorophenol > Phenol > Hydroquinone > 2,4-Dichlorophenol > p-Benzoquinone. The biosensor exhibited good sensitivity, stability for the tested phenolics compared to the reported working electrodes. It retained 65% of its initial activity after using for 300 measurements in one month.