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.

Determination of sex-specific 99th percentile upper reference limits for a point of care high sensitivity cardiac troponin I assay

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Fred S. Apple ◽  
Karen Schulz ◽  
Christian W. Schmidt ◽  
Trees S. Y. van Domburg ◽  
Judith M. Fonville ◽  
...  
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Limit Of Detection ◽  
Point Of Care ◽  
High Sensitivity ◽  
The Novel ◽  
Limit Of Quantitation ◽  
Reference Limits ◽  
Males And Females

Abstract Objectives High sensitivity (hs) cardiac troponin (cTn) assays are defined per the IFCC Committee on Clinical Application of Cardiac Biomarker (C-CB) by the ability to measure ≥ 50% of concentrations greater than the limit of detection (LoD) with an impression of ≤10% at sex-specific 99th percentiles. Our study determined the sex-specific 99th percentile upper reference limits for males and females utilizing heparinized plasma from AACC universal sample bank for the Siemens point of care (POC) Atellica® VTLi hs-cTnI immunoassay. Methods Apparently healthy subjects, included overall 693, males 363, and females 330, following exclusionary surrogate biomarker use of hemoglobin A1c, NT-proBNP, and eGFR, along with statin medication. hs-cTnI was measured in a central laboratory, on multiple POC Atellica® VTLi immunoassay analyzers. The LoD was 1.24 ng/L and limit of quantitation (CV 20%) was 6.7 ng/L. 99th percentile URLs were determined by the nonparametric (NP) method. Results Histograms of the hs-cTnI concentrations (ng/L) for males and females were used to visualize the distributions and concentrations in men and women and differed significantly (pre- and post-exclusion, both p <0.001). 99th percentile URLs were: overall 23 ng/L (90% CI 20–32 ng/L); male 27 ng/L (CI 21–37 ng/L); female 18 ng/L (CI 9–78 ng/L). The percentages of subjects having a measurable concentration ≥ the LoD were: overall 83.7%, male 87.3%, female 79.7%. Conclusions Our findings show the novel POC Atellica® VTLi hs-cTnI assay meets the designation of a ‘high-sensitivity’ assay using heparinized plasma.

Organotrialkoxysilane-mediated synthesis of functional noble metal nanoparticles and their bimetallic for electrochemical recognition of L-tryptophan

MRS Advances ◽  
2020 ◽  
Vol 5 (46-47) ◽  
pp. 2429-2444
Author(s):  
P.C. Pandey ◽  
Shubhangi Shukla ◽  
Govind Pandey ◽  
Roger J. Narayan
Keyword(s):  
Modified Electrode ◽  
Noble Metal ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Noble Metal Nanoparticles ◽  
Core Shell ◽  
Oxidation Potentials ◽  
Wide Range ◽  
Sequential Reduction

AbstractEffective and pH-sensitive electrochemical monitoring of L-tryptophan using noble metal nanocatalysts was evaluated in this study. This work examined the electrocatalytic influence of nanoparticles on the oxidation of amino acids with the variation of pH in working media. Bimetallic nanohybrids of palladium, silver, and gold (e.g., Pd/Ag and Pd/Au nanoparticles) were processed using organofunctionalized alkoxysilanes (3-aminopropyltrimethoxysilane (3-APTMS) and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (EETMOS)) via a sequential reduction pathway. Transmission electron microscopy (TEM) demonstrated the role of the alkoxysilanes in determining the size of the nanoparticles and the distribution of metals in the core-shell configuration. The cluster-like morphology of PdNPs was remodeled to form bimetallic nanomaterials (Pd-AuNPs and Pd-AgNPs) with a core-shell structure. Enhancement in the electrooxidation behavior was shown to depend on the nanomaterial and the pH of the medium. The Pd-AgNPs modified electrode exhibited high sensitivity and selectivity, with characteristic amplification in cathodic peak current at lower oxidation potentials (0.659 V, 0.782 V, and 0.890 V at pH values 4, 7, and 9, respectively) due to its greater stability. Differential pulse voltammetric (DPV) scans were recorded over a wide range of concentrations from 0.1 μM to 1000μM; the Pd-AgNPs modified electrode showed the lowest limit of detection of 0.1μM at pH 4, 0.5 μM at pH 7, and 0.5 μM at pH 9.

Determination of Bendiocarb Insecticide by Reverse Flow Injection Analysis Using a Solid-Phase Reactor Containing Micro PbO2, Nano PbO2 and Grafted SiO2 - PbO2 Immobilized

2020 ◽  
Vol 42 (1) ◽  
pp. 31-31
Author(s):  
Malik H Alaloosh Alamri Malik H Alaloosh Alamri ◽  
Sadeem Subhi Abed and Abdulkareem M A Alsammarraie Sadeem Subhi Abed and Abdulkareem M A Alsammarraie
Keyword(s):  
Flow Injection ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Reverse Flow ◽  
Blue Color ◽  
Wide Range ◽  
Solid Phase Reactor ◽  
Grafted Nanoparticles ◽  
Reverse Flow Injection

Bendiocarb (BEN) is an acutely toxic carbamate insecticide which used in public places and agriculture, it is also effective against a wide range of nuisance and disease vector insects. A new rapid and sensitive reverse flow injection spectrophotometric procedure coupled with on-line solid-phase reactor is designed in this article for the determination of BEN in its insecticidal formulations and water samples, by using three different solid-phase reactors containing bulk PbO2 (B-SPR), PbO2 nanoparticles (N-SPR) and grafted nanoparticles of SiO2-PbO2 (G-SPR) immobilized on cellulose acetate matrix (CA). This method of oxidative coupling is based on alkaline hydrolysis of the BEN pesticide, and then coupled with N,N dimethyl-p-phenylenediamine sulphate (DMPD) to give a blue color product which measured at λmax 675 nm. It worth to mentioned that under optimal conditions, Beer’s law is obeyed in the range of 1-175 μg mL-1 for B-SPR and 0.25-70 μg mL-1 of BEN for both N-SPR and G-SPR respectively within limit of detection (LOD) of 0.931, 0.234 and 0.210 μg mL-1 for B-SPR N-SPR and G-SPR respectively. The surface methodology of the solid phase was also investigated by using atomic force microscopy.

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.

Enzymatic determination of glucose in a flow system by catalytic oxidation of the nicotinamide coenzyme at a modified electrode

1985 ◽  
Vol 169 ◽  
pp. 237-247 ◽  
Author(s):  
Roger Appelqvist ◽  
György Marko-Varga ◽  
Lo Gorton ◽  
Arne Torstensson ◽  
Gillis Johansson
Keyword(s):  
Catalytic Oxidation ◽  
Modified Electrode ◽  
Flow System ◽  
Enzymatic Determination

scholarly journals Determination of cyanide in bamboo shoots by microdiffusion combined with ion chromatography–pulsed amperometric detection

2018 ◽  
Vol 5 (4) ◽  
pp. 172128 ◽  
Author(s):  
Ming Ding ◽  
Kailiang Wang
Keyword(s):  
Ion Chromatography ◽  
Limit Of Detection ◽  
Correlation Coefficients ◽  
Amperometric Detection ◽  
High Sensitivity ◽  
Practical Method ◽  
Pulsed Amperometric Detection ◽  
Bamboo Shoots ◽  
Relative Standard

A practical method for the determination of cyanide in bamboo shoots has been developed using microdiffusion preparation integrated with ion chromatography–pulsed amperometric detection (IC-PAD). Cyanide was released from bamboo shoots after Conway cell microdiffusion, and then analysed by IC-PAD. In comparison with the previously reported methods, derivatization and ion-pairing agent addition were not required in this proposed microdiffusion combined with IC-PAD method. The microdiffusion parameters were optimized including hydrolysis systems, temperature, time, and so on. Under the optimum conditions, the linear range of the calibration curve for cyanide was 0.2–200.0 µg kg −1 with satisfactory correlation coefficients of 0.9996 and the limit of detection was 0.2 µg kg −1 ( S/N  = 3). The spiked recovery range was from 92.8 to 98.6%. The intra-day and inter-day relative standard deviations of cyanide were 2.7–14.9% and 3.0–18.3%, respectively. This method was proved to be convenient in operation with high sensitivity, precision and accuracy, and was successfully applied in the determination of cyanide in bamboo shoot samples.

scholarly journals Non-enzymatic sensor for determination of glucose based on PtNi nanoparticles decorated graphene

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Risheng Li ◽  
Xu Deng ◽  
Longfei Xia
Keyword(s):  
Limit Of Detection ◽  
High Sensitivity ◽  
Glucose Detection ◽  
Serum Samples ◽  
Time Curve ◽  
Current Time ◽  
Glass Carbon ◽  
Graphene Glass ◽  
Ptni Alloy

Abstract Diabetes has become a universal epidemic in recent years. Herein, the monitoring of glucose in blood is of importance in clinical applications. In this work, PtNi alloy nanoparticles homogeneously dispersed on graphene (PtNi alloy-graphene) was synthesized as a highly effective electrode material for glucose detection. Based on the modified PtNi alloy-graphene/glass carbon (PtNi alloy-graphene/GC) electrode, it is found that the PtNi alloy-graphene/GC electrode exhibited excellent electrocatalytic performance on glucose oxidation. Furthermore, the results from amperometric current–time curve show a good linear range of 0.5–15 mM with the limit of detection of 16 uM (S/N = 3) and a high sensitivity of 24.03 uAmM−1 cm−2. On account of the good selectivity and durability, the modified electrode was successfully applied on glucose detection in blood serum samples.

Serotonin and its N-Acetylated and Acidic Derivatives in Insect Brain as Determined by High-Performance Liquid Chromatography with Electrochemical Detection

1993 ◽  
Vol 28 (1) ◽  
pp. 16-24 ◽  
Author(s):  
R. Vieira ◽  
M. Aldegunde
Keyword(s):  
Analytical Method ◽  
High Performance ◽  
Amperometric Detection ◽  
High Sensitivity ◽  
Hplc Method ◽  
Insect Brain ◽  
Oxidative Deamination ◽  
Wide Range ◽  
Hydrodynamic Voltammetry

The determination of serotonin (5-HT), N-acetylserotonin (NAS) and 5-hydroxy-3-indoleacetic acid (5-HIAA) in single brains of two acridids (Paracinema tricolor and Oedipoda caerulescens) was accomplished using a HPLC method combined with amperometric detection. A hydrodynamic voltammetry approach was used to assess the identity of each peak by comparing the voltammograms of standards and those of samples. The analytical method gave satisfactory reproducibility and sensitivity, and detected levels of 5-HT, NAS and 5-HIAA as low as 29, 55 and 10 fmol, respectively. This high sensitivity together with the simplicity of sample processing make the present analytical method suitable for a wide range of studies concerning indoleamine analyses in the insect nervous system. In both acridids, 5-HT showed the largest quantities, while its derivatives occurred in extremely low amounts. The results suggest that N-acetylation of 5-HT is quantitatively preferred to oxidative deamination in both species (NAS levels were 4-fold those of 5-HIAA). The relative importance of each catabolic pathway is discussed as related to physiological and genetic aspects.

A QCM Immunosensor for Rapid Determination of Ractopamine in Food Based on Enzyme-AuNPs for Signal Amplification and Magnetic β-Cyclodextrins for Extraction

2015 ◽  
Vol 738-739 ◽  
pp. 56-60
Author(s):  
Shu Xian Chen ◽  
Jing Liu ◽  
Dao Dong Pan ◽  
Ning Gan
Keyword(s):  
Signal Amplification ◽  
Rapid Determination ◽  
Screening Method ◽  
High Sensitivity ◽  
The Novel ◽  
Highly Sensitive ◽  
Reliable Quantification ◽  
Highly Sensitive Detection ◽  
Amplification Strategy

An enzyme amplified immunosensor for highly sensitive detection of Ractopamine (RAC) in foodstuff was developed based on quartz crystal microbalance (QCM). The high sensitivity was achieved by enzyme-AuNPs signal amplification strategy and magnetic β-cyclodextrins (β-CD) enrichment capacity. The novel QCM immunosensor which combines with the advantages of high selectivity of immunoassays and the high sensitivity of QCM has been developed for the determination of trace residues of RAC in food production. Under optimum conditions, the differences in the frequencies (∆f) of the QCM were proportional to the concentration of RAC over the range from 0.01 to 10 ng mL-1. The minimal detection limit was 0.01 ng mL-1. Due to its high sensitivity, acceptable stability and good selectivity, the immunosensor realized reliable quantification of RAC in real foodstuff. The proposed project has the potential to become a successful on-site screening method in food safety.

Analytical evaluation of the new Beckman Coulter Access high sensitivity cardiac troponin I immunoassay

2017 ◽  
Vol 56 (1) ◽  
Author(s):  
Giuseppe Lippi ◽  
Anna Ferrari ◽  
Giorgio Gandini ◽  
Matteo Gelati ◽  
Claudia Lo Cascio ◽  
...  
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Cardiac Troponin I ◽  
Analytical Performance ◽  
The Novel ◽  
Reference Limit ◽  
Automated Immunoassay ◽  
Upper Reference Limit

AbstractBackground:This study was aimed to evaluate the analytical performance of the novel chemiluminescent and fully-automated Beckman Coulter Access hsTnI high-sensitivity immunoassay for measurement of cardiac troponin I (cTnI).Methods:The study, using lithium heparin samples, included assessment of limit of blank (LOB), limit of detection (LOD), functional sensitivity, linearity, imprecision (within run, between-run and total), calculation of 99th percentile upper reference limit (URL) in 175 healthy blood donors (mean age, 36±12 years; 47% women) and comparison with two other commercial cTnI immunoassays.Results:The LOB, LOD and functional sensitivity of Access hsTnI were 0.14, 0.34 and 1.35 ng/L, respectively. The within-run, between-run and total imprecision was 2.2%–2.9%, 4.6%–5.4%, and 5.4%–6.1%, respectively. The linearity was excellent in the range of cTnI values between 0.95 and 4195 ng/L (r=1.00). The 99th percentile URL was 15.8 ng/L. Measurable cTnI values were found in 173/175 healthy subjects (98.9%). Good agreement of cTnI values was found with AccuTnI+3 (r=0.97; mean bias, −9.3%), whereas less satisfactory agreement was found with Siemens Dimension Vista cTnI (r=0.95; mean bias, −55%).Conclusions:The results of our evaluation of the Beckman Coulter Access hsTnI indicate that the analytical performance of this fully-automated immunoassay is excellent.

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