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Sensors, Volume 3, Issue 9 (September 2003) – 7 articles , Pages 330-403

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122 KiB  
Article
PVC Based Selective Sensors for Ni2+ Ions Using Carboxylated and Methylated Porphine
by L. P. Singh and J. M. Bhatnagar
Sensors 2003, 3(9), 393-403; https://doi.org/10.3390/s30900393 - 11 Sep 2003
Cited by 23 | Viewed by 6381
Abstract
Poly vinylchloride (PVC) based membranes of 4,4',4'',4'''-21H,23H-porphine–5,10,15,20 –tetrayl) tetrakis (benzoic acid) (TBAP) and 2,3,7,8,12,13,17,18-octamethyl - 21H, 23H-porphine (OMP) were prepared using dibutyl phthalate (DBP), dioctylphthalate (DOP), dibutyl(butyl)phosphonate (DBBP) and 1-chloronaphthalene (CN) as plastcizing solvent mediators and sodium tetraphenylborate (NaTPB) as an anion excluder [...] Read more.
Poly vinylchloride (PVC) based membranes of 4,4',4'',4'''-21H,23H-porphine–5,10,15,20 –tetrayl) tetrakis (benzoic acid) (TBAP) and 2,3,7,8,12,13,17,18-octamethyl - 21H, 23H-porphine (OMP) were prepared using dibutyl phthalate (DBP), dioctylphthalate (DOP), dibutyl(butyl)phosphonate (DBBP) and 1-chloronaphthalene (CN) as plastcizing solvent mediators and sodium tetraphenylborate (NaTPB) as an anion excluder for Ni2+ selective sensors. TBAP based membrane exhibits linearity over a wide concentration range 2.0x10-6–1.0x10-1M (0.12 – 5.8x103ppm) with a slope of 29.6 mV/decade of activity while OMP based membrane showed linear potential response in the concentration range 1.0x10-5 –1.0x 10-1M (0.60 – 5.8x103ppm) with a Nernstian slope of 29.0 mV/decade of activity. The electrode assembly works between pH 2.0 – 7.0, exhibits a fast response time of 10-15s and performed satisfactorily over a period of six months with good reproducibility. Excellent selectivity of the order of 10-3 over a number of cations and quantitative determination of Ni2+ in effluents discharged from electroplating industry demonstrates the utility of the proposed sensor. The electrode assembly was also used as an indicator electrode in the potentiometric titration of Ni2+ with EDTA. Full article
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2038 KiB  
Article
Chemical Sensors – from Molecules, Complex Mixtures to Cells – Supramolecular Imprinting Strategies
by Franz L. Dickert, Peter A. Lieberzeit, Oliver Hayden, Sylvia Gazda-Miarecka, Konstantin Halikias, Karl Jürgen Mann and Christian Palfinger
Sensors 2003, 3(9), 381-392; https://doi.org/10.3390/s30900381 - 11 Sep 2003
Cited by 17 | Viewed by 9018
Abstract
Methods of modern chemistry are a powerful tool in generating functional materials suitable as chemically sensitive layers to be combined with a variety of transducer principles. Molecular pits in polymers are formed by molecular imprinting, by suitable double-imprinting e.g. PAHs can be detected [...] Read more.
Methods of modern chemistry are a powerful tool in generating functional materials suitable as chemically sensitive layers to be combined with a variety of transducer principles. Molecular pits in polymers are formed by molecular imprinting, by suitable double-imprinting e.g. PAHs can be detected down to the sub-μg/l level. The resulting selectivity patterns depend both on the polymerization temperature and the template/mononomer composition. Organic contaminants in water can be either directly assessed in liquid phase or separated from the matrix by a porous Teflon membrane. Thus the detection limits can be reduced to the ppm-level due to the a much lower noise level in gaseous phase. Even complex processes such as engine oil degradation can be followed by suitably imprinted polymers. Pits on the nm- to μm scale are reached by surface templating polymers with microorganisms. The resulting layers show reversible, antibody-like interactions and thus are optimal sensor layers. The successful on-line detection of tobacco mosaic viruses (TMV) can be achieved by these surface imprinted layers. Full article
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181 KiB  
Article
Flow injection amperometric determination of persulfate in cosmetic products using a Prussian Blue film-modified electrode
by Marcelo F. De Oliveira, Adelir A. Saczk, Jose A. Gomes Neto, Paulo S. Roldan and Nelson R. Stradiotto
Sensors 2003, 3(9), 371-380; https://doi.org/10.3390/s30900371 - 11 Sep 2003
Cited by 22 | Viewed by 10047
Abstract
A flow-injection system with a glassy carbon disk electrode modified with Prussian Blue film is proposed for the determination of persulfate in commercial samples of hair bleaching boosters by amperometry. The detection was obtained by chronoamperometric technique and the sample is injected into [...] Read more.
A flow-injection system with a glassy carbon disk electrode modified with Prussian Blue film is proposed for the determination of persulfate in commercial samples of hair bleaching boosters by amperometry. The detection was obtained by chronoamperometric technique and the sample is injected into the electrochemical cell in a wall jet configuration. Potassium chloride at concentration of 0.1 mol L-1 acted as sample carrier at a flow rate of 4.0 mL min-1 and supporting-electrolyte. For 0.025 V (vs. Ag/AgCl) applied voltage, the proposed system handles ca. 160 samples per hour (1.0 10-4 - 1.0 10-3 mol L-1 of persulfate), consuming about 200 μL sample and 11 mg KCl per determination. Typical linear correlations between electrocatalytic current and persulfate concentration was ca. 0.9998. The detection limit is 9.0 10-5 mol L-1 and the calculated amperometric sensibility 3.6 103 μA L mol-1. Relative standard deviation (n =12) of a 1.0 10-4 mol L-1 sample is about 2.2%. The method was applied to persulfate determination in commercial hair-bleaching samples and results are in agreement with those obtained by titrimetry at 95% confidence level and good recoveries (95 - 112%) of spiked samples were found. Full article
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259 KiB  
Article
Detecting Pesticide Residue by Using Modulating Temperature Over a Single SnO2-Based Gas Sensor
by Xingjiu Huang, Jinhuai Liu, Zongxin Pi and Zengliang Yu
Sensors 2003, 3(9), 361-370; https://doi.org/10.3390/s30900361 - 11 Sep 2003
Cited by 15 | Viewed by 7949
Abstract
A new rapid detecting method (called dynamic measurements ) was reported to detect and distinguish the presence of two pesticide gases in the ambient atmosphere. The method employed only a single SnO2-based gas sensor in a rectangular temperature mode to perform the qualitative [...] Read more.
A new rapid detecting method (called dynamic measurements ) was reported to detect and distinguish the presence of two pesticide gases in the ambient atmosphere. The method employed only a single SnO2-based gas sensor in a rectangular temperature mode to perform the qualitative analysis of a binary gas mixture (acephate and trichlorphon) in air. Polar plots was used for quantitative analysis which the feature extraction was performed by FFT. Experimental results showed that high selectivity of the sensor achieved in the range of 250~3000C and modulating frequency 20mHz, one can easily observe the qualitative difference among the response to pure acephate and trichlorphon gases of the same concentration and to the mixture, and the concentration of pesticide gases can be obtained based on the changes of polar plots. Full article
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250 KiB  
Article
A Novel Hydrogen Peroxide Sensor via the Direct Electrochemistry of Horseradish Peroxidase Immobilized on Colloidal Gold Modified Screen-printed Electrode
by Xiaoxing Xu, Songqin Liu and Huangxian Ju
Sensors 2003, 3(9), 350-360; https://doi.org/10.3390/s30900350 - 11 Sep 2003
Cited by 59 | Viewed by 10599
Abstract
The direct electrochemistry of horseradish peroxidase (HRP) immobilized on a colloidal gold modified screen-printed carbon electrode (HRP-Au-SPCE) and its application as a disposable sensor were studied. The immobilized HRP displayed a couple of stable and well-defined redox peaks with a formal potential of [...] Read more.
The direct electrochemistry of horseradish peroxidase (HRP) immobilized on a colloidal gold modified screen-printed carbon electrode (HRP-Au-SPCE) and its application as a disposable sensor were studied. The immobilized HRP displayed a couple of stable and well-defined redox peaks with a formal potential of –0.338 V (vs. SCE) and a heterogeneous electron transfer rate constant of (0.75±0.04) s-1 in 0.1 M pH 7.0 PBS. It showed a highly thermal stability, fast amperometric response and an electrocatalytic activity to the reduction of hydrogen peroxide (H2O2) without the aid of an electron mediator. The biosensor exhibited high sensitivity, good reproducibility, and long-term stability for the determination of H2O2 with a linear range from 0.8 μM to 1.0 mM and a detection limit of 0. 4 μM at 3σ. The variation coefficients are 2.7 % and 2.3 % for over 10 successive assays at the H2O2 concentrations of 8.0 and 20 μM, respectively. The K M app for H2O2 sensor was determined to be 1.3 mM. Full article
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512 KiB  
Article
Monitoring of Milk Quality With Disposable Taste Sensor
by Maxsim Yap Mee Sim, Teo Jau Shya, Mohd Noor Ahmad, Ali Yeon Md Shakaff, Abdul Rahman Othman and Muhammad Suzuri Hitam
Sensors 2003, 3(9), 340-349; https://doi.org/10.3390/s30900340 - 11 Sep 2003
Cited by 33 | Viewed by 10927
Abstract
A disposable screen-printed multi channel taste sensor composed of several types of lipid as transducers and a computer as data analyzer could detect taste in a manner similar to human gustatory sensation. The disposable taste sensor was used to measure the electrical potential [...] Read more.
A disposable screen-printed multi channel taste sensor composed of several types of lipid as transducers and a computer as data analyzer could detect taste in a manner similar to human gustatory sensation. The disposable taste sensor was used to measure the electrical potential resulted from the interaction between lipid membranes and taste substances. In the present study, two types of packaged commercial milk, the ultra high temperature (UHT) and the pasteurized milk were tested. It was found that the disposable taste sensor is capable to discriminate reliably between fresh and spoiled milk and to follow the deterioration of the milk quality when it is stored at room temperature based on a pattern recognition principle namely Principle Component Analysis (PCA). This research could provide a new monitoring method ideally for simple and cheap decentralized testing for controlling the quality of milk, which may be of great use in the dairy industries. Full article
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719 KiB  
Article
Strategies of Miniaturised Reference Electrodes Integrated in a Silicon Based “one chip” pH Sensor
by Anette Simonis, Hans Lüth, Joseph Wang and J. Schöning
Sensors 2003, 3(9), 330-339; https://doi.org/10.3390/s30900330 - 11 Sep 2003
Cited by 16 | Viewed by 9337
Abstract
Different types of Ag/AgCl reference electrodes have been realised by means of thin- and thick-film technique. For inner electrolyte, KCl-containing membranes have been deposited and different coatings have been used to protect the reference electrode from a fast leaching out of KCl. The [...] Read more.
Different types of Ag/AgCl reference electrodes have been realised by means of thin- and thick-film technique. For inner electrolyte, KCl-containing membranes have been deposited and different coatings have been used to protect the reference electrode from a fast leaching out of KCl. The stability of the potential of the reference electrodes without KClcontaining membranes in 3 M KCl was about 7 hours for thin-film electrodes and up to 90 hours for thick-film electrodes. The reference electrodes with membrane were stable for more than two months. The thick-film reference electrode was integrated with a thin-film pH sensor onto one chip and the system pH sensor/reference electrode was investigated by means of capacitance/voltage (C/V) and constant capacitance (ConCap) mode. Full article
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