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Fernandes S, Tlemçani M, Bortoli D, Feliciano M, Lopes ME. A Portable Measurement Device Based on Phenanthroline Complex for Iron Determination in Water. SENSORS (BASEL, SWITZERLAND) 2023; 23:1058. [PMID: 36772098 PMCID: PMC9919581 DOI: 10.3390/s23031058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/10/2023] [Accepted: 01/12/2023] [Indexed: 06/18/2023]
Abstract
In this work, a newly developed self-contained, portable, and compact iron measurement system (IMS) based on spectroscopy absorption for determination of Fe2+ in water is presented. One of the main goals of the IMS is to operate the device in the field as opposed to instruments commonly used exclusively in the laboratory. In addition, the system has been tuned to quantify iron concentrations in accordance with the values proposed by the regulations for human consumption. The instrument uses the phenanthroline standard method for iron determination in water samples. This device is equipped with an optical sensing system consisting of a light-emitting diode paired with a photodiode to measure absorption radiation through ferroin complex medium. To assess the sensor response, four series of Fe2+ standard samples were prepared with different iron concentrations in various water matrices. Furthermore, a new solid reagent prepared in-house was investigated, which is intended as a "ready-to-use" sample pre-treatment that optimizes work in the field. The IMS showed better analytical performance compared with the state-of-the-art instrument. The sensitivity of the instrument was found to be 2.5 µg Fe2+/L for the measurement range established by the regulations. The linear response of the photodiode was determined for concentrations between 25 and 1000 µg Fe2+/L, making this device suitable for assessing iron in water bodies.
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Affiliation(s)
- Samuel Fernandes
- Department of Mechatronics Engineering, School of Science and Technology, Universidade de Évora, 7000-671 Évora, Portugal
- Instrumentation and Control Laboratory (ICL), Insititute of Earth Sciences (ICT), Universidade de Évora, 7000-671 Évora, Portugal
| | - Mouhaydine Tlemçani
- Department of Mechatronics Engineering, School of Science and Technology, Universidade de Évora, 7000-671 Évora, Portugal
- Instrumentation and Control Laboratory (ICL), Insititute of Earth Sciences (ICT), Universidade de Évora, 7000-671 Évora, Portugal
| | - Daniele Bortoli
- Instrumentation and Control Laboratory (ICL), Insititute of Earth Sciences (ICT), Universidade de Évora, 7000-671 Évora, Portugal
- Physics Department, School of Science and Technology (ECT), Universidade de Évora, 7000-671 Évora, Portugal
- Earth Remote Sensing Laboratory (EaRSLab), Institute of Earth Sciences (ICT), Universidade de Évora, 7000-671 Évora, Portugal
| | - Manuel Feliciano
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal
- Laboratório Associado para a Sustentabilidade e Tecnologia em Regiões de Montanha (SusTEC), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal
| | - Maria Elmina Lopes
- Department of Chemistry and Biochemistry, School of Science and Technology (ECT), Universidade de Évora, 7000-671 Evora, Portugal
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Monolithic Integrated OLED–OPD Unit for Point-of-Need Nitrite Sensing. SENSORS 2022; 22:s22030910. [PMID: 35161655 PMCID: PMC8838366 DOI: 10.3390/s22030910] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/14/2022] [Accepted: 01/21/2022] [Indexed: 02/06/2023]
Abstract
In this study, we present a highly integrated design of organic optoelectronic devices for Point-of-Need (PON) nitrite (NO2−) measurement. The spectrophotometric investigation of nitrite concentration was performed utilizing the popular Griess reagent and a reflection-based photometric unit with an organic light emitting diode (OLED) and an organic photodetector (OPD). In this approach a nitrite concentration dependent amount of azo dye is formed, which absorbs light around ~540 nm. The organic devices are designed for sensitive detection of absorption changes caused by the presence of this azo dye without the need of a spectrometer. Using a green emitting TCTA:Ir(mppy)3 OLED (peaking at ~512 nm) and a DMQA:DCV3T OPD with a maximum sensitivity around 530 nm, we successfully demonstrated the operation of the OLED–OPD pair for nitrite sensing with a low limit of detection 46 µg/L (1.0 µM) and a linearity of 99%. The hybrid integration of an OLED and an OPD with 0.5 mm × 0.5 mm device sizes and a gap of 0.9 mm is a first step towards a highly compact, low cost and highly commercially viable PON analytic platform. To our knowledge, this is the first demonstration of a fully organic-semiconductor-based monolithic integrated platform for real-time PON photometric nitrite analysis.
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All Silica Micro-Fluidic Flow Injection Sensor System for Colorimetric Chemical Sensing. SENSORS 2021; 21:s21124082. [PMID: 34198500 PMCID: PMC8231821 DOI: 10.3390/s21124082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/08/2021] [Accepted: 06/11/2021] [Indexed: 12/22/2022]
Abstract
This paper presents a miniature, all-silica, flow-injection sensor. The sensor consists of an optical fiber-coupled microcell for spectral absorption measurements and a microfluidic reagent injection system. The proposed sensor operates in back reflection mode and, with its compact dimensions, (no more than 200 µm in diameter) enables operation in small spaces and at very low flow rates of analyte and reagent, thus allowing for on-line or in-line colorimetric chemical sensing.
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Li D, Wang T, Li Z, Xu X, Wang C, Duan Y. Application of Graphene-Based Materials for Detection of Nitrate and Nitrite in Water-A Review. SENSORS 2019; 20:s20010054. [PMID: 31861855 PMCID: PMC6983230 DOI: 10.3390/s20010054] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/10/2019] [Accepted: 12/16/2019] [Indexed: 12/14/2022]
Abstract
Nitrite and nitrate are widely found in various water environments but the potential toxicity of nitrite and nitrate poses a great threat to human health. Recently, many methods have been developed to detect nitrate and nitrite in water. One of them is to use graphene-based materials. Graphene is a two-dimensional carbon nano-material with sp2 hybrid orbital, which has a large surface area and excellent conductivity and electron transfer ability. It is widely used for modifying electrodes for electrochemical sensors. Graphene based electrochemical sensors have the advantages of being low cost, effective and efficient for nitrite and nitrate detection. This paper reviews the application of graphene-based nanomaterials for electrochemical detection of nitrate and nitrite in water. The properties and advantages of the electrodes were modified by graphene, graphene oxide and reduced graphene oxide nanocomposite in the development of nitrite sensors are discussed in detail. Based on the review, the paper summarizes the working conditions and performance of different sensors, including working potential, pH, detection range, detection limit, sensitivity, reproducibility, repeatability and long-term stability. Furthermore, the challenges and suggestions for future research on the application of graphene-based nanocomposite electrochemical sensors for nitrite detection are also highlighted.
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Affiliation(s)
- Daoliang Li
- College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China
- China-EU Center for Information and Communication Technologies in Agriculture, China Agricultural University, Beijing 100083, China
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture, China Agricultural University, Beijing 100083, China
- Beijing Engineering and Technology Research Center for Internet of Things in Agriculture, China Agricultural University, Beijing 100083, China
- Correspondence:
| | - Tan Wang
- College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China
- China-EU Center for Information and Communication Technologies in Agriculture, China Agricultural University, Beijing 100083, China
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture, China Agricultural University, Beijing 100083, China
- Beijing Engineering and Technology Research Center for Internet of Things in Agriculture, China Agricultural University, Beijing 100083, China
| | - Zhen Li
- College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China
- China-EU Center for Information and Communication Technologies in Agriculture, China Agricultural University, Beijing 100083, China
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture, China Agricultural University, Beijing 100083, China
- Beijing Engineering and Technology Research Center for Internet of Things in Agriculture, China Agricultural University, Beijing 100083, China
| | - Xianbao Xu
- College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China
- China-EU Center for Information and Communication Technologies in Agriculture, China Agricultural University, Beijing 100083, China
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture, China Agricultural University, Beijing 100083, China
- Beijing Engineering and Technology Research Center for Internet of Things in Agriculture, China Agricultural University, Beijing 100083, China
| | - Cong Wang
- College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China
- China-EU Center for Information and Communication Technologies in Agriculture, China Agricultural University, Beijing 100083, China
- Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture, China Agricultural University, Beijing 100083, China
- Beijing Engineering and Technology Research Center for Internet of Things in Agriculture, China Agricultural University, Beijing 100083, China
| | - Yanqing Duan
- Business school, University of Bedfordshire, Luton LU1 3BE, UK;
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