Photochemically mediated synthesis of a gold colloid by dithizone and its application in the amperometric sensing of thiocyanate

RSC Advances ◽  
2015 ◽  
Vol 5 (99) ◽  
pp. 81660-81667 ◽  
Author(s):  
Sandeep Gupta ◽  
Rajiv Prakash
Keyword(s):  
Modified Electrode ◽  
Limit Of Detection ◽  
Gold Colloid ◽  
One Step ◽  
Amperometric Sensing ◽  
Photochemical Route

Au–DTZH was synthesized by a one-step photochemical route and used for the amperometric sensing of thiocyanate. The modified electrode has a sensitivity of 16 nA nM−1 and a limit of detection of 23.35 nM at a potential of 0.55 V vs. Ag/AgCl.

An Improved Sensitivity Non-Enzymatic Glucose Sensor Based on a Nano-Gold Modified Ag Electrode

2012 ◽  
Vol 503 ◽  
pp. 427-431 ◽  
Author(s):  
Jia Hong He ◽  
Qiang Xu ◽  
Zhi Qiang Gao ◽  
Zhong Rong Song
Keyword(s):  
Electron Microscopy ◽  
Modified Electrode ◽  
Glucose Sensor ◽  
Current Response ◽  
Gold Colloid ◽  
Ag Electrode ◽  
Nano Gold ◽  
Transmission Electron ◽  
Highly Sensitive ◽  
Amperometric Sensing

A non-enzymatic glucose sensor based on nano-gold modified Ag electrode was fabricated by two steps. Gold colloid were firstly prepared according to the literature[11] and then a carefully cleaned Ag electrode was dipped into the gold colloid to obtain the non-enzymatic glucose sensor. The structures and morphologies of nano-gold colloid and nano-Au modified electrode were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis absorption spectra. The direct electrocatalytic oxidation of glucose in alkaline medium at this modified electrode has been investigated in detail. The result showed that the nano-gold modified electrode had good current response to glucose. The oxidation current was linearly related to the concentration of glucose range frome 0.2 to 175.2μmol/L with a detection limit of 29.5 nmol/L. The nano-gold modified electrode allows highly sensitive, low working potential, fast amperometric sensing of glucose, thus is promising for the future development of non-enzymatic glucose sensors.

scholarly journals Highly Selective and Reproducible Electrochemical Sensing of Ascorbic Acid Through a Conductive Polymer Coated Electrode

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1346 ◽  
Author(s):  
Salma Bilal ◽  
Ayesha Akbar ◽  
Anwar-ul-Haq Ali Shah
Keyword(s):  
Ascorbic Acid ◽  
Cyclic Voltammetry ◽  
Modified Electrode ◽  
Limit Of Detection ◽  
Conductive Polymer ◽  
Micelle Formation ◽  
Electrochemical Sensing ◽  
A Value ◽  
One Step ◽  
Doped Polyaniline

The surface of an Au-disc electrode was modified through electro polymerization of aniline, in the presence of dodecyl benzene sulphonic acid (DBSA) and sulphuric acid (H2SO4) solution. The polymerization conditions were pre-optimized so that micelle formation and solution coagulation could be minimized and surfactant doped polyaniline film could be obtained through a quick, simple and one step polymerization route. The synthesized material was characterized via Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and cyclic voltammetry (CV). The effective surface area of the Au-disc, calculated through cyclic voltammetry, was immensely increased through a polyaniline (PANI) coating (0.04 and 0.11 cm2 for bare and PANI coated gold respectively). The modified electrode was utilized for ascorbic acid (AA) sensing. The changing pH of electrolyte and scan rate influenced the PANI electrode response towards AA. The modified electrode was highly selective towards AA oxidation and showed a very low limit of detection i.e. 0.0267 μmol·L–1. Moreover, the PANI coating greatly reduced the sensing potential for AA by a value of around 140 mV when compared to that on a bare gold electrode.

scholarly journals ELECTROCHEMICAL AND CHEMOMETRIC DETERMINATION OF DORZOLAMIDE AND TIMOLOL IN EYE DROPS USING MODIFIED MULTIWALL CARBON NANOTUBE ELECTRODE

2017 ◽  
Vol 9 (9) ◽  
pp. 43 ◽  
Author(s):  
Hassan A.m. Hendawy ◽  
Hanan M. Elwy ◽  
Amany M. Fekry
Keyword(s):  
Modified Electrode ◽  
Limit Of Detection ◽  
Partial Least Square ◽  
Least Square ◽  
Fractional Factorial ◽  
Great Promise ◽  
Multiwall Carbon Nanotube ◽  
Eye Drops ◽  
Multiwall Carbon

Objective: This work is focused on the construction of simple and sensitive electrochemical sensor for quantitative determination of dorzolamide (DOR) and timolol maleate (TIM). This method is based on the incorporation of multiwall carbon nanotubes (MWCNT) into the carbon paste electrode which improve the characteristics of the electrode.Methods: The electrochemical response of modified electrode was based on voltammetric oxidation, using cyclic voltammetry (CV) and impedance spectroscopy (EIS). The structural morphology of the surface modified electrode was characterized by scanning electron microscope (SEM). Quantitative analysis for each of the two compounds in a mixture has been examined by using of chemometric tools for resolving overlapping signals. The prediction performance of the chemometric method was analyzed by principal component regression (PCR) and partial least square (PLS).Results: Fractional factorial design was constructed from set of synthetic mixtures of two drugs in concentration ranges of 0.05 to 1.6µg/ml for DOR and 1.5-20 µg/ml for TIM. Under optimum experimental conditions, DOR and TIM gave rectilinear response over the concentration range of 0.072-1.88 µg/ml and 1.16-20.84 µg/ml, respectively. The limit of detection (LOD) was found to be 0.098 and 1.025 µg/ml, for DOR and TIM, respectively. It found that the % of relative prediction error (RPE) was acceptable and satisfactory.Conclusion: In these work, for the first time, a new voltammetric simultaneous method developed for a rapid and efficient determination of DOR and TIM from eye dropper sample at nano modified electrode with satisfactory results. These results indicate that MWCNT holds great promise in practical application.

scholarly journals Copper-nickel oxide nanofilm modified electrode for non-enzymatic determination of glucose

2020 ◽  
Vol 10 (3) ◽  
pp. 245-255
Author(s):  
Mahsa Hasanzadeh ◽  
Zahra Hasanzadeh ◽  
Sakineh Alizadeh ◽  
Mehran Sayadi ◽  
Mojtaba Nasiri Nezhad ◽  
...  
Keyword(s):  
Modified Electrode ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Stability Loss ◽  
The Novel ◽  
Step Potential ◽  
Enzymatic Determination ◽  
Wide Range ◽  
Naoh Solution

CuxO-NiO nanocomposite film for the non-enzymatic determination of glucose was prepared by the novel modifying method. At first, anodized Cu electrode was kept in a mixture solution of CuSO4, NiSO4 and H2SO4 for 15 minutes. Then, a cathodization process with a step potential of -6 V in a mixture solution of CuSO4 and NiSO4 was initiated, generating formation of porous Cu-Ni film on the bare Cu electrode by electrodeposition assisted by the release of hydrogen bubbles acting as soft templates. Optimized conditions were determined by the experimental design software for electrodeposition process. Afterward, Cu-Ni modified electrode was scanned by cyclic voltammetry (CV) method in NaOH solution to convert Cu and Ni nanoparticles to the nano-scaled CuxO-NiO film. The electrocatalytic behavior of the novel CuxO-NiO film toward glucose oxidation was studied by CV and chronoamperometry (CHA) techniques. The calibration curve of glucose was found linear in a wide range of 0.04–5.76 mM, with a low limit of detection (LOD) of 7.3 µM (S/N = 3) and high sensitivity (1.38 mA mM-1 cm-2). The sensor showed high selectivity against some usual interfering species and high stability (loss of only 6.3 % of its performance over one month). The prepared CuxO-NiO nanofilm based sensor was successfully applied for monitoring glucose in human blood serum and urine samples.

scholarly journals Electro-Oxidation and Simultaneous Determination of Indole-3-Acetic Acid and Salicylic Acid on Graphene Hydrogel Modified Electrode

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5483 ◽  
Author(s):  
Xiaodong Cao ◽  
Xueting Zhu ◽  
Shudong He ◽  
Xuan Xu ◽  
Yongkang Ye
Keyword(s):  
Acetic Acid ◽  
Salicylic Acid ◽  
Modified Electrode ◽  
Limit Of Detection ◽  
Simultaneous Detection ◽  
Three Dimensional ◽  
Linear Sweep Voltammetry ◽  
Oxidation Reactions ◽  
Sensor Performance ◽  
Indole 3 Acetic Acid

A selective and sensitive electrochemical sensor was developed for simultaneous detection of phytohormones indole-3-acetic acid (IAA) and salicylic acid (SA). The sensing interface was fabricated on a porous, three-dimensional networked graphene hydrogel (GH) modified glassy carbon electrode (GCE). The electrocatalytic behavior of IAA and SA on the surface of the modified electrode (GH/GCE) was investigated by cyclic voltammetry and linear sweep voltammetry. Results show that the oxidation reactions of IAA and SA occur at different potentials, which enable their simultaneous detection at the sensing interface. Under optimal conditions, the GH/GCE exhibited good selectivity and stability and its response, unaffected by various interferents, was linear in the range of 4 to 200 μM of IAA and SA. The limit of detection (S/N = 3) achieved were 1.42 μM for IAA and 2.80 μM for SA. The sensor performance was validated by measuring for IAA and SA in real vegetable samples with satisfactory results.

Metallic Film Modified Screen-Printed Carbon Electrode for Determination of 17α-Methyltestosterone

2019 ◽  
Vol 824 ◽  
pp. 182-189
Author(s):  
Chim Math ◽  
Wijitar Dungchai ◽  
Sudtida Pliankarom Thanasupsin
Keyword(s):  
Modified Electrode ◽  
Limit Of Detection ◽  
Diffusion Mechanism ◽  
Modified Electrodes ◽  
Active Surface ◽  
Deposition Potential ◽  
Active Surface Area ◽  
Male Population ◽  
Screen Printed Carbon Electrode ◽  
Screen Printed

17α-methyltestosterone (MT) is a synthetic androgen. It is used widely for inducing an all-male population of Nile tilapia (Oreochromis niloticus). In this work, the detection of MT was conducted using screen-printed carbon electrodes (SPCE). These were a bare electrode, a bismuth modified electrode (Bi-SPCE) and an antimony modified electrode (Sb-SPCE). The successful electrode modification was confirmed by scanning electron microscopy. The electroanalytical performance of the SPCE modified electrodes for MT detection was examined by cyclic voltammetry. The highest active surface area of 1.073x10-4 cm2 was obtained on Sb-SPCE. This indicates that Sb-SPCE can enhance the sensitivity of MT detection better than the bare-SPCE and the Bi-SPCE. The Sb-SPCE showed a linear response for MT concentrations ranging from 2 to 8 mg.L-1. The sensitivity obtained from the slope of a calibration curve was -0.452 mA.mol-1.L-1 in a Britton-Robinson buffer pH 4.0 containing Sb 16 mg.L-1 with deposition potential and deposition time of 1 V and 90 seconds, respectively. A linear relationship between the square root of the scan rate and the peak current revealed that mass transfer of MT to the electrode was driven by a diffusion mechanism. The limit of detection was found to be 1 mg.L-1.

scholarly journals Canine distemper virus detection by different methods of One-Step RT-qPCR

2016 ◽  
Vol 46 (9) ◽  
pp. 1601-1606
Author(s):  
Claudia de Camargo Tozato ◽  
Vívian Ferreira Zadra ◽  
Caroline Rodrigues Basso ◽  
João Pessoa Araújo Junior
Keyword(s):  
Urine Sample ◽  
Canine Distemper Virus ◽  
Limit Of Detection ◽  
Analytical Sensitivity ◽  
Canine Distemper ◽  
System A ◽  
Virus Rna ◽  
One Step ◽  
Commercial Kits ◽  
The One

ABSTRACT: Three commercial kits of One-Step RT-qPCR were evaluated for the molecular diagnosis of Canine Distemper Virus. Using the kit that showed better performance, two systems of Real-time RT-PCR (RT-qPCR) assays were tested and compared for analytical sensitivity to Canine Distemper Virus RNA detection: a One-Step RT-qPCR (system A) and a One-Step RT-qPCR combined with NESTED-qPCR (system B). Limits of detection for both systems were determined using a serial dilution of Canine Distemper Virus synthetic RNA or a positive urine sample. In addition, the same urine sample was tested using samples with prior centrifugation or ultracentrifugation. Commercial kits of One-Step RT-qPCR assays detected canine distemper virus RNA in 10 (100%) urine samples from symptomatic animals tested. The One-Step RT-qPCR kit that showed better results was used to evaluate the analytical sensitivity of the A and B systems. Limit of detection using synthetic RNA for the system A was 11 RNA copies µL-1 and 110 RNA copies µl-1 for first round System B. The second round of the NESTED-qPCR for System B had a limit of detection of 11 copies µl-1. Relationship between Ct values and RNA concentration was linear. The RNA extracted from the urine dilutions was detected in dilutions of 10-3 and10-2 by System A and B respectively. Urine centrifugation increased the analytical sensitivity of the test and proved to be useful for routine diagnostics. The One-Step RT-qPCR is a fast, sensitive and specific method for canine distemper routine diagnosis and research projects that require sensitive and quantitative methodology.

An efficient photochemical route to Pd nanoparticles; application to the one-step synthesis of Pd@polymer nanocomposite films

2016 ◽  
Vol 27 (34) ◽  
pp. 345601 ◽  
Author(s):  
Séverine Wolak ◽  
Loïc Vidal ◽  
Jean-Michel Becht ◽  
Laure Michelin ◽  
Lavinia Balan
Keyword(s):  
Polymer Nanocomposite ◽  
Pd Nanoparticles ◽  
Nanocomposite Films ◽  
One Step ◽  
The One ◽  
Photochemical Route

High Throughput Determination of BTEX by a One-Step Fluorescence Polarization Immunoassay

2005 ◽  
Vol 2 (3) ◽  
pp. 227 ◽  
Author(s):  
Sergei A. Eremin ◽  
Dietmar Knopp ◽  
Reinhard Niessner ◽  
Ji Youn Hong ◽  
Song-Ja Park ◽  
...  
Keyword(s):  
Fluorescence Polarization ◽  
Limit Of Detection ◽  
Petroleum Products ◽  
Cross Reactivity ◽  
Rapid Screening ◽  
Fluorescence Polarization Immunoassay ◽  
Phenylcarboxylic Acids ◽  
One Step ◽  
Benzene Toluene

Environmental Context.Benzene, toluene, ethylbenzene, and xylenes (BTEX) are used as solvents in paints and coatings and are constituents of petroleum products. BTEX can contaminate air, water or soil and is toxic; benzene, in particular, is a recognized human carcinogen. Most existing methods for detecting BTEX are time-consuming, complicated and very expensive for routine screening. A rapid immunoassay of BTEX is presented that greatly simplifies environmental monitoring of water contamination. Abstract.For the rapid screening of BTEX (benzene, toluene, ethylbenzene, xylenes), a fluorescence polarization immunoassay (FPIA) was developed using the fluorescence polarization analyzer Abbott TDx. Several fluorescence-labelled tracers were synthesized by binding ethylenediamine fluorescein thiocarbamyl (EDF) to various substituted phenylcarboxylic acids. The binding of 27 tracers with two antisera that can be considered as class-specific for BTEX was investigated to select optimal tracer–antibody pairs. Significant differences were found in binding, titer, sensitivity, and assay kinetics. A best pair of anti-BTEX antiserum and EDF-labelled p-tolylacetic acid tracer was selected for FPIA. To simplify the method, an immunocomplex single reagent was prepared to detect BTEX by a one-step FPIA. One-step FPIA is a rapid homogeneous type of immunoassay that has only one pipetting step, does not need separation of free and bound analyte and can be performed at room temperature. The within-run coefficient of variation was ranged between 3.4% and 5.7%. Furthermore, if the measurement can be done at constant temperature, standards for every assay run are unnecessary. Cross-reactivity studies of petroleum compounds and a BTEX mixture indicated that p-xylene was most reactive with a limit of detection (LOD) of 0.22 µg mL−1 in 50 µL of sample. The LOD for toluene and benzene was 2.1 and 11 µg mL−1 respectively. The immunocomplex single reagent has proven to be significantly more stable than the corresponding solutions of antibody and tracer.

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