scholarly journals Evaluation of IUPAC limit of detection and ISO minimum detectable value - electrochemical determination of lead

2021 ◽  
Vol 9 (1) ◽  
pp. 91-100
Author(s):  
Ján Mocák ◽  
Ivan Janiga ◽  
Estera Rábarová
Keyword(s):  
Surface Water ◽  
Theoretical Analysis ◽  
Trace Analysis ◽  
Limit Of Detection ◽  
Electrochemical Determination ◽  
Measurement Process ◽  
Performance Characteristics ◽  
The Way

The way of calculating the limit of detection recommended by IUPAC is compared to the minimum detectable value used by ISO as one of the most important performance characteristics of a measurement process. In this work, theoretical analysis of both characteristics is given together with directions for their practical use. Calculations are exemplified using electrochemical trace analysis of lead in surface water.

scholarly journals Zinc/Aluminium–Quinclorac Layered Nanocomposite Modified Multi-Walled Carbon Nanotube Paste Electrode for Electrochemical Determination of Bisphenol A

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 941 ◽  
Author(s):  
Rahadian Zainul ◽  
Nurashikin Abd Azis ◽  
Illyas Md Isa ◽  
Norhayati Hashim ◽  
Mohamad Syahrizal Ahmad ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Bisphenol A ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Electrochemical Determination ◽  
Multiwalled Carbon ◽  
Baby Bottle ◽  
Double Hydroxide ◽  
Paste Electrode

This paper presents the application of zinc/aluminium-layered double hydroxide-quinclorac (Zn/Al-LDH-QC) as a modifier of multiwalled carbon nanotubes (MWCNT) paste electrode for the determination of bisphenol A (BPA). The Zn/Al-LDH-QC/MWCNT morphology was examined by a transmission electron microscope and a scanning electron microscope. Electrochemical impedance spectroscopy was utilized to investigate the electrode interfacial properties. The electrochemical responses of the modified electrode towards BPA were thoroughly evaluated by using square-wave voltammetry technique. The electrode demonstrated three linear plots of BPA concentrations from 3.0 × 10−8–7.0 × 10−7 M (R2 = 0.9876), 1.0 × 10−6–1.0 × 10−5 M (R2 = 0.9836) and 3.0 × 10−5–3.0 × 10−4 M (R2 = 0.9827) with a limit of detection of 4.4 × 10−9 M. The electrode also demonstrated good reproducibility and stability up to one month. The presence of several metal ions and organic did not affect the electrochemical response of BPA. The electrode is also applicable for BPA determination in baby bottle and mineral water samples with a range of recovery between 98.22% and 101.02%.

scholarly journals A label-free biosensor based on graphene and reduced graphene oxide dual-layer for electrochemical determination of beta-amyloid biomarkers

2020 ◽  
Vol 187 (5) ◽  
Author(s):  
Jagriti Sethi ◽  
Michiel Van Bulck ◽  
Ahmed Suhail ◽  
Mina Safarzadeh ◽  
Ana Perez-Castillo ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Limit Of Detection ◽  
Electrochemical Techniques ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Label Free ◽  
Reduced Graphene ◽  
Electrochemically Reduced Graphene Oxide

AbstractA label-free biosensor is developed for the determination of plasma-based Aβ1–42 biomarker in Alzheimer’s disease (AD). The platform is based on highly conductive dual-layer of graphene and electrochemically reduced graphene oxide (rGO). The modification of dual-layer with 1-pyrenebutyric acid N-hydroxysuccinimide ester (Pyr-NHS) is achieved to facilitate immobilization of H31L21 antibody. The effect of these modifications were studied with morphological, spectral and electrochemical techniques. The response of the biosensor was evaluated using differential pulse voltammetry (DPV). The data was acquired at a working potential of ~ 180 mV and a scan rate of 50 mV s−1. A low limit of detection (LOD) of 2.398 pM is achieved over a wide linear range from 11 pM to 55 nM. The biosensor exhibits excellent specificity over Aβ1–40 and ApoE ε4 interfering species. Thus, it provides a viable tool for electrochemical determination of Aβ1–42. Spiked human and mice plasmas were used for the successful validation of the sensing platform in bio-fluidic samples. The results obtained from mice plasma analysis concurred with the immunohistochemistry (IHC) and magnetic resonance imaging (MRI) data obtained from brain analysis.

scholarly journals Electrochemical determination of acetaminophen at a carbon electrode modified in the presence of β-cyclodextrin: role of the activated glassy carbon and the electropolymerised β-cyclodextrin

2021 ◽  
Author(s):  
Bronach Healy ◽  
Francesco Rizzuto ◽  
Marida de Rose ◽  
Tian Yu ◽  
Carmel B. Breslin
Keyword(s):  
Glassy Carbon ◽  
Electrochemical Sensors ◽  
Limit Of Detection ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Phosphate Solution ◽  
Carbon Electrode ◽  
Provide Pain Relief ◽  
High Concentrations

AbstractAcetaminophen is a well-known drug commonly used to provide pain relief, but it can also lead to acute liver failure at high concentrations. Therefore, there is considerable interest in monitoring its concentrations. Sensitive and selective acetaminophen electrochemical sensors were designed by cycling a glassy carbon electrode (GCE) to high potentials in the presence of β-CD in a phosphate electrolyte, or by simply activating the GCE electrode in the phosphate solution. Using cyclic voltammetry, adsorption-like voltammograms were recorded. The acetaminophen oxidation product, N-acetyl benzoquinone imine, was protected from hydrolysis, and this was attributed to the adsorption of acetaminophen at the modified GCE. The rate constants for the oxidation of acetaminophen were estimated as 4.3 × 10–3 cm2 s–1 and 3.4 × 10–3 cm2 s–1 for the β-CD-modified and -activated electrodes, respectively. Using differential pulse voltammetry, the limit of detection was calculated as 9.7 × 10–8 M with a linear concentration range extending from 0.1 to 80 μM. Furthermore, good selectivity was achieved in the presence of caffeine, ascorbic acid and aspirin, enabling the determination of acetaminophen in a commercial tablet. Similar electrochemical data were obtained for both the β-CD-modified and activated GCE surfaces, suggesting that the enhanced detection of acetaminophen is connected mainly to the activation and oxidation of the GCE. Using SEM, EDX and FTIR, no evidence was obtained to indicate that the β-CD was electropolymerised at the GCE.

scholarly journals Determination of Pharmaceutical Residues by UPLC-MS/MS Method: Validation and Application on Surface Water and Hospital Wastewater

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bui Van Hoi ◽  
Cam-Tu Vu ◽  
Lan-Anh Phung-Thi ◽  
Thao Thi Nguyen ◽  
Phuong Thanh Nguyen ◽  
...  
Keyword(s):  
Surface Water ◽  
Analytical Method ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Multiple Reaction Monitoring ◽  
Hospital Wastewater ◽  
Esi Ms ◽  
Pharmaceutical Residues ◽  
Detection Frequency

In this study, an analytical method for the simultaneous determination of 7 major pharmaceutical residues in Vietnam, namely, carbamazepine, ciprofloxacin, ofloxacin, ketoprofen, paracetamol, sulfamethoxazole, and trimethoprim, in surface water and hospital wastewater has been developed. The method includes enrichment and clean-up steps by solid phase extraction using mix-mode cation exchange, followed by identification and quantification using an ultrahigh-performance liquid chromatography and tandem mass spectrometry and employing electrospray ionization (UPLC-ESI-MS/MS). Seven target compounds were separated on the reversed phase column and detected in multiple reaction monitoring (MRM) mode within 6 minutes. The present study also optimized the operating parameters of the mass spectrometer to achieve the highest analytical signals for all target compounds. All characteristic parameters of the analytical method were investigated, including linearity range, limit of detection, limit of quantification, precision, and accuracy. The important parameter in UPLC-ESI-MS/MS, matrix effect, was assessed and implemented via preextraction and postextraction spiking experiments. The overall recoveries of all target compounds were in the ranges from 55% to 109% and 56 % to 115% for surface water and hospital wastewater, respectively. Detection limits for surface water and hospital wastewater were 0.005–0.015 µg L−1 and 0.014–0.123 µg L−1, respectively. The sensitivity of the developed method was allowed for determination of target compounds at trace level in environmental water samples. The in-house validation of the developed method was performed by spiking experiment in both the surface water and hospital wastewater matrix. The method was then applied to analyze several surface water and hospital wastewater samples taken from West Lake and some hospitals in Vietnam, where the level of these pharmaceutical product residues was still missed. Sulfamethoxazole was present at a high detection frequency in both surface water (33% of analyzed samples) and hospital wastewater (81% of analyzed samples) samples.

Indirect Electrochemical Determination of Chlorpropamide Through Its Interaction with Valsartan Using Square Wave Voltammetry

2021 ◽  
pp. 6541-6544
Author(s):  
Amer Th. Al-Taee ◽  
Aws Z. Al-Hafidh
Keyword(s):  
Limit Of Detection ◽  
Silver Chloride ◽  
Detection System ◽  
Reference Electrode ◽  
Electrochemical Determination ◽  
Square Wave ◽  
The Stability ◽  
Silver Silver ◽  
Silver Silver Chloride

A square wave voltammetric technique coupled with three electrode detection system consist of hanging mercury drop electrode (HMDE) as working electrode, 1mm platinum wire as an auxiliary electrode (Pt-wire) and silver/silver chloride saturated potassium chloride (Ag/AgCl.sat.KCl) as reference electrode was used to determine the chlorpropamide indirectly through its interaction with valsartan, chlorpropamide gives no reduction peaks in the studied range. The effect of pH and the stability of the measurement were examined calibrations curve of chlorpropamide was constructed and the relation between current and concentration of chlorpropamide was linear with R2 value = 0.9944. The limit of detection for chlorpropamide was 4.89 x 10-9 M through its interaction with valsartan.

scholarly journals Electrochemical Determination of Paracetamol Using Fe3O4/Reduced Graphene-Oxide-Based Electrode

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Nguyen Thi Anh Thu ◽  
Hoang Van Duc ◽  
Nguyen Hai Phong ◽  
Nguyen Duc Cuong ◽  
Nguyen Thi Vuong Hoan ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Limit Of Detection ◽  
Anodic Stripping Voltammetry ◽  
Electrochemical Determination ◽  
Spherical Particles ◽  
Current Response ◽  
X Ray ◽  
Reduced Graphene

The synthesis of magnetic iron oxide/reduced graphene oxide (Fe3O4/rGO) and its application to the electrochemical determination of paracetamol using Fe3O4/rGO modified electrode were demonstrated. The obtained materials were characterized by means of X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), and magnetic measurement. The results showed that Fe3O4/rGO composite exhibited high specific surface area, and its morphology consists of very fine spherical particles of Fe3O4 in nanoscales. Fe3O4/rGO was used as an electrode modifier for the determination of paracetamol by differential pulse-anodic stripping voltammetry (DP-ASV). The preparation of Fe3O4/rGO-based electrode and some factors affecting voltammetric responses were investigated. The results showed that Fe3O4/rGO is a potential electrode modifier for paracetamol detection by DP-ASV with a low limit of detection. The interfering effect of uric acid, ascorbic acid, and dopamine on the current response of paracetamol has been reported. The repeatability, reproducibility, linear range, and limit of detection were also addressed. The proposed method could be applied to the real samples with satisfactory results.

scholarly journals Development of an Immunofluorescence Assay Module for Determination of the Mycotoxin Zearalenone in Water

Toxins ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 182
Author(s):  
Borbála Gémes ◽  
Eszter Takács ◽  
Patrik Gádoros ◽  
Attila Barócsi ◽  
László Kocsányi ◽  
...  
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
High Performance ◽  
Limit Of Detection ◽  
Fusarium Species ◽  
Chemical Properties ◽  
Organic Carbon Content ◽  
Emerging Pollutant

Project Aquafluosense is designed to develop prototypes for a fluorescence-based instrumentation setup for in situ measurements of several characteristic parameters of water quality. In the scope of the project an enzyme-linked fluorescent immunoassay (ELFIA) method has been developed for the detection of several environmental xenobiotics, including mycotoxin zearalenone (ZON). ZON, produced by several plant pathogenic Fusarium species, has recently been identified as an emerging pollutant in surface water, presenting a hazard to aquatic ecosystems. Due to its physico-chemical properties, detection of ZON at low concentrations in surface water is a challenging task. The 96-well microplate-based fluorescence instrument is capable of detecting ZON in the concentration range of 0.09–400 ng/mL. The sensitivity and accuracy of the analytical method has been demonstrated by a comparative assessment with detection by high-performance liquid chromatography and by total internal reflection ellipsometry. The limit of detection of the method, 0.09 ng/mL, falls in the low range compared to the other reported immunoassays, but the main advantage of this ELFIA method is its efficacy in combined in situ applications for determination of various important water quality parameters detectable by induced fluorimerty—e.g., total organic carbon content, algal density or the level of other organic micropollutants detectable by immunofluorimetry. In addition, the immunofluorescence module can readily be expanded to other target analytes if proper antibodies are available for detection.

Electrochemical Determination of Norepinephrine at Poly (p-aminobenzenesulfonic Acid) Modified Sensor

2020 ◽  
Vol 16 (5) ◽  
pp. 591-600
Author(s):  
Şevket Zişan Yağcı ◽  
Ebru Kuyumcu Savan ◽  
Gamze Erdoğdu
Keyword(s):  
Ascorbic Acid ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Buffer Solution ◽  
Oxidation Current ◽  
Pulse Voltammetry ◽  
Modified Sensor

Objective: In this study, it was aimed to prepare an electrochemical sensor capable of assigning Norepinephrine in the presence of an interference such as ascorbic acid. Methods: A sensitive modified sensor was prepared by electrodeposition of p-aminobenzenesulfonic acid (p-ABSA) to the glassy carbon electrode by cyclic voltammetry. The electrooxidation of Norepinephrine was accomplished by cyclic and differential pulse voltammetry. Results: The current values were enhanced and the peak potentials of Norepinephrine and ascorbic acid were separated at the sensor compared to the bare electrode. There was linearity between the oxidation current and concentration of Norepinephrine ranging from 0.5 to 99.8 μM in phosphate buffer solution at pH 7.0. The limit of detection was 10.0 nM and the sensitivity was 0.455 μA/μM. Conclusion: The determination of Norepinephrine was successfully performed in real samples such as blood serum and urine at the poly (p-ABSA) sensor. To the best of our knowledge, this is the first study to detect Norepinephrine in the presence of ascorbic acid at poly (p-ABSA) modified sensor in the literature.

scholarly journals The Torsional Quartz-Crystal Viscometer

2021 ◽  
Vol 42 (8) ◽  
Author(s):  
William A. Wakeham ◽  
Stephen M. Richardson
Keyword(s):  
Theoretical Analysis ◽  
Resonant Frequency ◽  
Theoretical Basis ◽  
Quartz Crystal ◽  
Solid Dynamics ◽  
First Time ◽  
Modern Instrumentation ◽  
The Way

AbstractA complete theoretical analysis of the fluid and solid dynamics of the torsional quartz crystal viscometer is presented which for the first time, establishes a firm theoretical basis for two working equations whereby the viscosity of a fluid may be determined from measurements of the resonant frequency of the crystal and the width of the resonance when immersed in the fluid. Modern instrumentation means that it is possible to achieve higher resolution in the measurement of these two quantities than hitherto and the new theory opens the way to securing a concomitant accuracy in the determination of viscosity.

Simultaneous Determination of Anionic, Amphoteric and Cationic Surfactants Mixtures in Surface Water

2018 ◽  
Vol 69 (1) ◽  
pp. 27-30 ◽  
Author(s):  
Iuliana Paun ◽  
Vasile Ion Iancu ◽  
Liliana Cruceru ◽  
Marcela Niculescu ◽  
Florentina Laura Chiriac
Keyword(s):  
Surface Water ◽  
Simultaneous Determination ◽  
Cationic Surfactants ◽  
Anionic Surfactants ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Acetate Solution ◽  
Limit Of Quantitation ◽  
Amphoteric Surfactants

A simple, reliable and accurate HPLC/CAD method was developed for the determination of anionic (sodium dioctyl sulfosuccinate and sodium 1-dodecane sulfonate), amphoteric (CHAPS (3-[(3-Cholamidopropyl) dimethylammonium]-1-propanesulfonate hydrate)) and cationic (benzethonium chloride) surfactants mixture from surface water samples. The chromatographic analysis was performed on an Acclaim Surfactant Plus (150 x 3.0 mm, 3 mm d.p.) column acquired from Thermo Scientific, kept at 300C. All experiments were performed in gradient elution conditions at a flow-rate of 0.6 mL/min. Mobile phase composition was a mixture of acetonitrile (A) and 0.1 M ammonium acetate solution acidified to pH 5 with acetic acid (B). The limit of detection (LD) were 20 mg/L for anionic surfactants and 30 mg/L for cationic and amphoteric surfactants. The calibration curves were linear between 15 mg/L � 110 mg/L, with R2 values above 0.992 for all surfactants. Solid phase extraction (SPE) using polymeric (Strata X) cartridges has been applied to extract and concentrate the target analytes from the synthetic samples. Surfactants recoveries after SPE procedure were situated between 91.5�94.6%. Intra-day and inter-day precision (RSD%) were situated between 4.0 � 7.7% and 7.5 � 11.7%, respectively. Limit of quantitation (LQ) was lower than 80 mg/L for anionic surfactants and 90 mg/L for cationic and 100 mg/L for amphoteric surfactants. The new sensitive and selective HPLC/CAD developed method allows simultaneous determination of anionic, amphoteric and cationic surfactants mixture from environmental samples (surface water).

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