TY - JOUR AU - Mendes, J. P. AU - Coelho, L. AU - Kovács, Barna AU - de, Almeida J. M. M. M. AU - Pereira, C. M. AU - Jorge, P. A. S. AU - Borges, M. T. TI - Dissolved Carbon Dioxide Sensing Platform for Freshwater and Saline Water Applications: Characterization and Validation in Aquaculture Environments JF - SENSORS J2 - SENSORS-BASEL VL - 19 PY - 2019 IS - 24 PG - 16 SN - 1424-8220 DO - 10.3390/s19245513 UR - https://m2.mtmt.hu/api/publication/31254369 ID - 31254369 N1 - Funding Agency and Grant Number: North Portugal Regional Operational Program (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement; European Regional Development Fund (ERDF)European Union (EU) [UID/EEA/50014/2019, UID/QUI/00081/2019, UID/Multi/04423/2019]; RAS-ORGMAT (ERA-NET COFASP) [FCT COFASP/0005/2015] Funding text: This work is financed by the North Portugal Regional Operational Program (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, and through the European Regional Development Fund (ERDF)."within projects "UID/EEA/50014/2019", "UID/QUI/00081/2019", "UID/Multi/04423/2019", and "RAS-ORGMAT (ERA-NET COFASP, refa FCT COFASP/0005/2015)". AB - A sensing configuration for the real-time monitoring, detection, and quantification of dissolved carbon dioxide (dCO(2)) was developed for aquaculture and other applications in freshwater and saline water. A chemical sensing membrane, based on a colorimetric indicator, is combined with multimode optical fiber and a dual wavelength light-emitting diode (LED) to measure the dCO(2)-induced absorbance changes in a self-referenced ratiometric scheme. The detection and processing were achieved with an embeded solution having a mini spectrometer and microcontroller. For optrode calibration, chemical standard solutions using sodium carbonate in acid media were used. Preliminary results in a laboratory environment showed sensitivity for small added amounts of CO2 (0.25 mg.L-1). Accuracy and response time were not affected by the type of solution, while precision was affected by salinity. Calibration in freshwater showed a limit of detection (LOD) and a limit of quantification (LOQ) of 1.23 and 1.87 mg.L-1, respectively. Results in saline water (2.5%) showed a LOD and LOQ of 1.05 and 1.16 mg.L-1, respectively. Generally, performance was improved when moving from fresh to saline water. Studies on the dynamics of dissolved CO2 in a recirculating shallow raceway system (SRS+RAS) prototype showed higher precision than the tested commercial sensor. The new sensor is a compact and robust device, and unlike other sensors used in aquaculture, stirring is not required for correct and fast detection. Tests performed showed that this new sensor has a fast accurate detection as well as a strong potential for assessing dCO(2) dynamics in aquaculture applications. LA - English DB - MTMT ER - TY - CHAP AU - Coelho, L AU - Pereira, C AU - Mendes, J AU - De Almeida, J M M M AU - Kovács, Barna AU - Balogh, K AU - Borges, T AU - Jorge, P A S ED - [s n, ] TI - New developments on fibre optic colorimetrie sensors for dissolved CO2 in aquatic environments T2 - OCEANS 2017 - Aberdeen PB - IEEE Press CY - New York, New York SN - 9781509052783 PY - 2017 PG - 5 DO - 10.1109/OCEANSE.2017.8084989 UR - https://m2.mtmt.hu/api/publication/3360861 ID - 3360861 LA - English DB - MTMT ER - TY - JOUR AU - Kiss, László AU - Kovács, Barna AU - Nagy, Géza TI - Direct chronoamperometric determination of free available chlorine in soil samples using built-in diffusion layer coated glassy carbon electrode JF - JOURNAL OF SOLID STATE ELECTROCHEMISTRY J2 - J SOLID STATE ELECTR VL - 19 PY - 2015 IS - 1 SP - 261 EP - 267 PG - 7 SN - 1432-8488 DO - 10.1007/s10008-014-2596-7 UR - https://m2.mtmt.hu/api/publication/2777545 ID - 2777545 N1 - Export Date: 27 January 2024 AB - In this work, a glassy carbon electrode supplied with a built-in diffusion layer and a short-time chronoamperometric method were used for obtaining reliable concentration values from I-t curves recorded in tortuous media. It was proved that short-time chronoamperometric transients taken with the modified electrode in tortuous matrices can be evaluated using calibrating data recorded in simple aqueous standards. The applicability of the in situ analytical method was tested for determination of active chlorine concentration in different bleaching powder treated soil samples. Iodometric titrations were employed for comparison. The results prove that residual concentration of active chlorine can be estimated with 0.66 % relative standard deviation using the proposed in situ chronoamperometric measuring methods in humid soil slurry after bleaching powder disinfection. © 2014 Springer-Verlag Berlin Heidelberg. LA - English DB - MTMT ER - TY - JOUR AU - Őri, Zsuzsanna Emese AU - Nagy, Lívia AU - Kiss, László AU - Kovács, Barna AU - Nagy, Géza TI - Direct Voltammetric Determination of Ascorbic Acid in Natural Paprika Fruits Without Sample Pretreatment JF - ELECTROANALYSIS J2 - ELECTROANAL VL - 27 PY - 2015 IS - 3 SP - 808 EP - 816 PG - 9 SN - 1040-0397 DO - 10.1002/elan.201400603 UR - https://m2.mtmt.hu/api/publication/2848643 ID - 2848643 N1 - Export Date: 27 January 2024; CODEN: ELANE LA - English DB - MTMT ER - TY - JOUR AU - Markovics, Ákos AU - Kovács, Barna TI - Optical Ammonia Sensors for Environmental Applications JF - ANALYTICAL LETTERS J2 - ANAL LETT VL - 47 PY - 2014 IS - 3 SP - 465 EP - 477 PG - 13 SN - 0003-2719 DO - 10.1080/00032719.2013.843188 UR - https://m2.mtmt.hu/api/publication/2777546 ID - 2777546 AB - Triphenyl-methane based indicators bromophenol blue and bromocresol green were immobilized in ormosil sol-gel films prepared from phenyl-triethoxysilane in order to prepare colorimetric ammonia sensors. The sensing layers contained different molar ratios of the indicators, in this way-depending on the pKa values of the indicators-sensors with tailored dynamic ranges could be fabricated. Adsorption based immobilization was also used for the fabrication of chemical layers immersing anodized aluminum films in aqueous solutions of the indicators. Simultaneous immobilization of the indicators was considerably effortful on the anodized aluminum film, compared with the sol-gel film; therefore, the significant temperature dependency of the sensor response was used to shift the dynamic range. The effect of an ionic liquid additive was also investigated to increase the lifetime of these sensors. All sensors were tested spectrophotometrically, although a simple reflection based read-out device was also constructed using two light emitting diodes as light sources and two photodiodes as detectors. The device did not produce a concentration dependent signal but gave a digital yes or no (1 or 0) indicating that ammonia concentrations had reached a preset level. © 2014 Copyright Taylor and Francis Group, LLC. LA - English DB - MTMT ER - TY - JOUR AU - Szili, Mónika AU - Kasik, I AU - Matejec, V AU - Nagy, Géza AU - Kovács, Barna TI - Poly(luminol) based sensor array for determination of dissolved chlorine in water JF - SENSORS AND ACTUATORS B-CHEMICAL J2 - SENSOR ACTUAT B CHEM VL - 192 PY - 2014 SP - 92 EP - 98 PG - 7 SN - 0925-4005 DO - 10.1016/j.snb.2013.10.080 UR - https://m2.mtmt.hu/api/publication/2777547 ID - 2777547 N1 - Funding Agency and Grant Number: foundation "Synthesis of supramolecular systems, examination of their physicochemical properties and their utilization for separation and sensor chemistry" [SROP-4.2.2.A-11/1] Funding text: The authors, M. Szili, G. Nagy, B. Kovacs appreciate the support of the foundation "Synthesis of supramolecular systems, examination of their physicochemical properties and their utilization for separation and sensor chemistry" (SROP-4.2.2.A-11/1). AB - An optical sensor for determination of free chlorine content of drinking water was prepared and tested. The function of the sensor is based on detecting chemiluminescence signal provided by thin immobilized poly(luminol) reagent layer. The poly(luminol) reagent film was prepared by electropolymerization of luminol onto planar indium-tin-oxide (ITO) electrode. Different methods, like electrode potential cyclization (cyclic voltammetry, CV), pulsed potential electrolysis (pulsed amperometry, PA) and potentiostatic electrolysis (constant potential electrolysis, PSE) were employed for preparation of the poly(luminol) layer. The chemoluminescence (chemiluminescence) of the differently prepared films was investigated in the poly(luminol) - hypochlorite - hydrogen peroxide reaction. Highest luminescence signal was obtained by the films prepared with CV. Poly(luminol) layers deposited with pulsed potential showed 80% less luminescence while almost no signal was obtained in case of films made with constant potential technique. The effects of the buffer composition and pH on the analytical properties of the electro polymerized sensing layer were investigated. The lower concentration limit of free chlorine detection was 5 × 10-7 M in phosphate buffer at pH = 8.0. It was found that the chemiluminescence signal decreased significantly when hypochlorite concentrations over 1 mM were applied. An array of 24 micro wells was fabricated on ITO glass slab of about microscope slide size. The individual micro wells had identical volume and the poly(luminol) layer immobilized on their bottom had identical activity. The wells could be used for "single shot" determination of free chlorine content of drinking water. The long storage stability, the simple measurement procedure and low feasible concentration range makes the array an attractive analytical tool. Its applicability was proved measuring dissolved chlorine concentration of tap water samples. © 2013 Elsevier B.V. All rights reserved. LA - English DB - MTMT ER - TY - JOUR AU - Balogh, K AU - Jesusc, JM AU - Gouveia, C AU - Domingues, JO AU - Markovics, A AU - Baptista, JM AU - Kovács, Barna AU - Pereira, CM AU - Borges, M-T AU - Jorge, PAS TI - Characterization of a novel dissolved CO2 sensor for utilization in environmental monitoring and aquaculture industry JF - PROCEEDINGS OF SPIE - THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING J2 - PROCEEDINGS OF SPIE VL - 8785 PY - 2013 SP - 8785FC SN - 9780819496010 SN - 0277-786X DO - 10.1117/12.2027518 UR - https://m2.mtmt.hu/api/publication/2781072 ID - 2781072 LA - English DB - MTMT ER - TY - JOUR AU - Kiss, László AU - Őri, Zsuzsanna Emese AU - Nagy, Lívia AU - Kovács, Barna AU - Nagy, Géza TI - Voltammetric concentration measurements in diffusion-hindered media JF - JOURNAL OF SOLID STATE ELECTROCHEMISTRY J2 - J SOLID STATE ELECTR VL - 17 PY - 2013 IS - 12 SP - 3039 EP - 3045 PG - 7 SN - 1432-8488 DO - 10.1007/s10008-013-2178-0 UR - https://m2.mtmt.hu/api/publication/2364658 ID - 2364658 N1 - Export Date: 27 January 2024 LA - English DB - MTMT ER - TY - JOUR AU - Markovics, Ákos AU - Kovács, Barna TI - Fabrication of optical chemical ammonia sensors using anodized alumina supports and sol–gel method JF - TALANTA J2 - TALANTA VL - 109 PY - 2013 IS - 0 SP - 101 EP - 106 PG - 6 SN - 0039-9140 DO - 10.1016/j.talanta.2013.01.054 UR - https://m2.mtmt.hu/api/publication/2241729 ID - 2241729 N1 - Funding Agency and Grant Number: Developing Competitiveness of Universities in the South Transdanubian Region [SROP-4.2.1.B-10/2/KONV-2010-0002] Funding text: The work was partly supported by "Developing Competitiveness of Universities in the South Transdanubian Region" (Grant no. SROP-4.2.1.B-10/2/KONV-2010-0002). AB - In this comparative study, the fabrication and the sensing properties of various reflectometric optical ammonia gas sensors are described. In the first set of experiments the role of the support material was investigated on four different sensor membranes. Two of them were prepared by the adsorption of bromocresol green indicator on anodized aluminum plates. The applied anodizing voltages were 12 V and 24 V, which resulted in different dynamic ranges and response times for gaseous ammonia. The sol–gel method was used for the preparation of the other batch of sensors. These layers were coated on anodized aluminum plates (24 V) and on standard microscope cover glasses. In spite of the identical sensing chemistry, slightly different response times were measured merely because of the aluminum surface porosity. Gas molecules can remain entrapped in the pores, which results in delayed recovery time. On the other hand, the porous oxide film provides excellent adhesion, making the anodized aluminum an attractive support for the sol–gel layer. LA - English DB - MTMT ER - TY - JOUR AU - Gouveia, C AU - Balogh, Katalin AU - Baptista, JM AU - Kovács, Barna AU - Jorge, PAS TI - LPG Based fiber optic sensor for carbon dioxide JF - PROCEEDINGS OF SPIE - THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING J2 - PROCEEDINGS OF SPIE VL - 8421 PY - 2012 SP - 84216L SN - 9780819491039 SN - 0277-786X DO - 10.1117/12.975279 UR - https://m2.mtmt.hu/api/publication/2781054 ID - 2781054 LA - English DB - MTMT ER -