Anodic Adsorptive Stripping Voltammetric Determination of Rafoxanide on Glassy Carbon Electrode

2020 ◽  
Vol 23 (10) ◽  
pp. 1002-1009
Author(s):  
Abd-Elgawad Radi ◽  
Hassan El-samboskany
Keyword(s):  
Glassy Carbon ◽  
Fasciola Hepatica ◽  
Limit Of Detection ◽  
Bovine Milk ◽  
Active Agent ◽  
Human Consumption ◽  
Irreversible Adsorption ◽  
Simple Method ◽  
Ph Range

Background: Rafoxanide (RFX) is an active agent against Fasciola hepatica, but it is prohibited for treatment of dairy animals whose milk is provided for human consumption. Objective: A reliable, fast, and simple method needs to be developed to monitor RFX residues in milk samples before distribution to consumers. Methods: In this work, the electrochemical oxidation of RFX was studied at glassy carbon electrodes (GCE) in Britton-Robinson buffer (BR) solutions over the pH range 2.0-12.0 using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The oxidation of the drug was accomplished in a single irreversible, adsorption-controlled step within the pH range 4.0-9.0. Therefore, the application of GCE for a sensitive and selective quantification of RFX by adsorptive stripping voltammetry was reported. The accumulation of the analyte was performed in Britton–Robinson buffer (pH 5.0) at a potential of -0.3 V (vs. Ag-AgCl-KClsat) for 300 s and the measurement was carried out, after medium exchange, in BR solution of pH 7.0 using DPV. Result and Conclusion: This format was satisfactorily applied for the determination of RFX in bovine milk. Limit of detection (LOD) of 1.25 µg kg -1 of milk and mean recoveries of 97.8 to 107.5% were achieved.

Novel palladium(II) selective membrane electrode based on 4-[(5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl]benzene-1,3-diol

2010 ◽  
Vol 75 (5) ◽  
pp. 563-575 ◽  
Author(s):  
Moslem Mohammadi ◽  
Mehdi Khodadadian ◽  
Mohammad K. Rofouei
Keyword(s):  
Limit Of Detection ◽  
Membrane Electrode ◽  
Aqueous Samples ◽  
Selective Determination ◽  
Poly Vinyl Chloride ◽  
Selective Membrane ◽  
Ph Range ◽  
Palladium Content ◽  
Methyl Benzene

A plasticized poly(vinyl chloride) membrane electrode based on 4-[(5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl]benzene-1,3-diol (L) for highly selective determination of palladium(II) (in PdCl42– form) is developed. The electrode showed a good Nernstian response (29.6 ± 0.4 mV per decade) over a wide concentration range (3.1 × 10–7 to 1.0 × 10–2 mol l–1). The limit of detection was 1.5 × 10–7 mol l–1. The electrode has a response time of about 20 s, and it can be used for at least 2 months without observing any considerable deviation from Nernstian response. The proposed electrode could be used in the pH range of 2.5–5.5. The practical utility of the electrode has been demonstrated by its use for the estimation of palladium content in aqueous samples.

scholarly journals Surface-Enhanced Oxidation and Determination of Isothipendyl Hydrochloride at an Electrochemical Sensing Film Constructed by Multiwalled Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
S. N. Prashanth ◽  
Shankara S. Kalanur ◽  
Nagappa L. Teradal ◽  
J. Seetharamappa
Keyword(s):  
Limit Of Detection ◽  
Biological Fluids ◽  
Differential Pulse ◽  
Electrochemical Sensing ◽  
Good Precision ◽  
Multiwalled Carbon ◽  
Limit Of Quantification ◽  
Surface Enhanced ◽  
Ph Range

The electrochemical behavior of isothipendyl hydrochloride (IPH) was investigated at bare and multiwalled-carbon-nanotube modified glassy carbon electrode (MWCNT-GCE). IPH (55 μM) showed two oxidation peaks in Britton-Robinson (BR) buffer of pH 7.0. The oxidation process of IPH was observed to be irreversible over the pH range of 2.5–9.0. The influence of pH, scan rate, and concentration of the drug on anodic peak was studied. A differential pulse voltammetric method with good precision and accuracy was developed for the determination of IPH in pure and biological fluids. The peak current was found to be linearly dependent on the concentration of IPH in the range of 1.25–55 μM. The values of limit of detection and limit of quantification were noticed to be 0.284 and 0.949 μM, respectively.

scholarly journals Gold Nanoparticles with Different Particle Sizes for the Quantitative Determination of Chlorpyrifos Residues in Soil by SERS

2019 ◽  
Vol 20 (11) ◽  
pp. 2817 ◽  
Author(s):  
Yong He ◽  
Shupei Xiao ◽  
Tao Dong ◽  
Pengcheng Nie
Keyword(s):  
Gold Nanoparticles ◽  
Limit Of Detection ◽  
Soil Surface ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Substrate ◽  
Least Squares Regression ◽  
Simple Method ◽  
Good Linear ◽  
Relative Standard

Chlorpyrifos (CPF) is widely used in the prevention and control of crop pests and diseases in agriculture. However, the irrational utilization of pesticides not only causes environmental pollution but also threatens human health. Compared with the conventional techniques for the determination of pesticides in soil, surface-enhanced Raman spectroscopy (SERS) has shown great potential in ultrasensitive and chemical analysis. Therefore, this paper reported a simple method for synthesizing gold nanoparticles (AuNPs) with different sizes used as a SERS substrate for the determination of CPF residues in soil for the first time. The results showed that there was a good linear correlation between the SERS characteristic peak intensity of CPF and particle size of the AuNPs with an R2 of 0.9973. Moreover, the prepared AuNPs performed great ultrasensitivity, reproducibility and chemical stability, and the limit of detection (LOD) of the CPF was found to be as low as 10 μg/L. Furthermore, the concentrations ranging from 0.01 to 10 mg/L were easily observed by SERS with the prepared AuNPs and the SERS intensity showed a good linear relationship with an R2 of 0.985. The determination coefficient (Rp2) reached 0.977 for CPF prediction using the partial least squares regression (PLSR) model and the LOD of CPF residues in soil was found to be as low as 0.025 mg/kg. The relative standard deviation (RSD) was less than 3.69% and the recovery ranged from 97.5 to 103.3%. In summary, this simple method for AuNPs fabrication with ultrasensitivity and reproducibility confirms that the SERS is highly promising for the determination of soil pesticide residues.

Simultaneous Multiresidue Analysis of (β-Lactam Antibiotics in Bovine Milk by Liquid Chromatography with Ultraviolet Detection and Confirmation by Electrospray Mass Spectrometry

1994 ◽  
Vol 77 (5) ◽  
pp. 1122-1131 ◽  
Author(s):  
Krystyna L Tyczkowska ◽  
Robert D Voyksner ◽  
Rolf F Straub ◽  
Arthur L Aronson
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Simultaneous Determination ◽  
Electrospray Mass Spectrometry ◽  
Limit Of Detection ◽  
Water Solution ◽  
Bovine Milk ◽  
Penicillin G ◽  
Array Detector

Abstract A multiresidue analytical method was developed for the simultaneous determination of amoxicillin, cephapirin, procaine penicillin G, ampicil-lin, cloxacillin, and ceftiofur in bovine milk. The method involved ultrafiltration of milk diluted with an equal volume of 50% acetonitrile through a 10 000 dalton molecular mass cutoff filter. Separation of these β-lactam antibiotics from other milk components was performed by ion-paired (octane- and dodecanesulfonate) liquid chromatography using a phenyl column eluted with acetonitrile-water solution. Ultraviolet ab-sorbance of the column effluent was monitored in the 200-350 nm range of a photodiode-array detector. For quantitation, the chromatograms were acquired at λ210 nm for penicillin G, am-picillin, and cloxacillin; λ230 nm for amoxicillin; and λ290 for cephapirin, procaine, and ceftiofur. The limit of detection for the simultaneous determination of these antibiotics was estimated to be 100 ppb. Liquid chromatography/electrospray mass spectrometry could be used to confirm these antibiotics for quantities down to 100 pg entering the mass spectrometer.

scholarly journals Stripping Voltammetric Determination of Analgesics in Their Pharmaceuticals Using Nano-Riboflavin-Modified Glassy Carbon Electrode

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Gopalakrishnan Gopu ◽  
Paramasivam Manisankar ◽  
Baladhandapani Muralidharan ◽  
Chinnapiyan Vedhi
Keyword(s):  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Limit Of Detection ◽  
Pharmaceutical Preparations ◽  
Sem Analysis ◽  
Carbon Electrode ◽  
Modified Glassy Carbon Electrode ◽  
Diffusion Controlled ◽  
Influence Of Ph

Cyclic voltammetric behaviors of three analgesics, acetaminophen (AAP), acetylsalicylic acid (ASA), and dipyrone (DP), were studied using nano-riboflavin-modified glassy carbon electrode. One well-defined oxidation peak each for AAP and ASA and three oxidation peaks for DP were observed. The influence of pH, scan rate, and concentration reveals irreversible diffusion controlled reaction. The SEM analysis confirmed good accumulation of the drugs on the electrode surface. Calibration was made under the maximum peak current conditions. The concentration range studied for the determination of drugs was 0.02 to 0.4 μg mL−1for AAP and ASA and 0.025 to 0.4 μg mL−1for DP. The lower limit of detection observed for AAP, ASA, and DP was 0.016, 0.007 μg mL−1, and 0.013 μg mL−1, respectively. The suitability of the method for the determination of these analgesics in pharmaceutical preparations and urine samples was also ascertained.

scholarly journals Voltammetric determination of dopamine in the presence of ascorbic and uric acids using partial least squares regression: determination of dopamine in human urine and plasma

2009 ◽  
Vol 7 (3) ◽  
pp. 524-531 ◽  
Author(s):  
Morteza Bahram ◽  
Khalil Farhadi ◽  
Farzin Arjmand
Keyword(s):  
Least Squares ◽  
Partial Least Squares ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Limit Of Detection ◽  
Relative Standard Error ◽  
Carbon Electrode ◽  
Least Squares Regression ◽  
Relative Standard

AbstractA new differential pulse voltammetric method for dopamine determination at a bare glassy carbon electrode has been developed. Dopamine, ascorbic acid (AA) and uric acid (UA) usually coexist in physiological samples. Because AA and UA can be oxidized at potentials close to that of DA it is difficult to determine dopamine electrochemically, although resolution can be achieved using modified electrodes. Additionally, oxidized dopamine mediates AA oxidation and the electrode surface can be easily fouled by the AA oxidation product. In this work a chemometrics strategy, partial least squares (PLS) regression, has been applied to determine dopamine in the presence of AA and UA without electrode modification. The method is based on the electrooxidation of dopamine at a glassy carbon electrode in pH 7 phosphate buffer. The dopamine calibration curve was linear over the range of 1–313 μM and the limit of detection was 0.25 μM. The relative standard error (RSE %) was 5.28%. The method has been successfully applied to the measurement of dopamine in human plasma and urine.

Determination of diltiazem based on the reduction of Cu(II)–BCA complexes in micellar medium

2010 ◽  
Vol 88 (6) ◽  
pp. 533-539 ◽  
Author(s):  
Larissa Zuppardo Lacerda Sabino ◽  
Daniele Cestari Marino ◽  
Horacio Dorigan Moya
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Confidence Level ◽  
Limit Of Detection ◽  
Calibration Graph ◽  
Micellar Medium ◽  
Solution Ph ◽  
Simple Method ◽  
Relative Standard

A simple method was developed for determining microquantities of diltiazem, based on the reduction of copper(II) in buffered solution (pH 7.0) and the use of a micellar medium containing 4,4′-dicarboxy-2,2′-biquinoline acid. The copper(I) produced reacts with 4,4′-dicarboxy-2,2′-biquinoline acid and the complexes formed are spectrophotometrically measured at 558 nm. A typical calibration graph shows good linearity (r = 0.993) from 20 to 100 μg mL–1 of diltiazem. The limit of detection and relative standard deviation were calculated as 12 μg mL–1 (99% confidence level) and 3.5% (40 μg mL–1; n = 6), respectively, with a mean recovery value of 96.5% found in pharmaceutical dosages. A straightforward and effective way to recycle the reagents is addressed. The hazardous aspects of the Cu(I)–BCA reaction are presented as well.

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 patulin in apple juice by liquid chromatography-electrospray tandem mass spectrometry

2021 ◽  
Vol 854 (1) ◽  
pp. 012075
Author(s):  
T Radicevic ◽  
S Jankovic ◽  
S Simunovic ◽  
S Stefanovic ◽  
Z Petrovic ◽  
...  
Keyword(s):  
Apple Juice ◽  
Limit Of Detection ◽  
Fruit Juices ◽  
Human Consumption ◽  
Human Diet ◽  
Maximum Residue Limits ◽  
Commission Regulation ◽  
Apple Products ◽  
Infants And Young Children

Abstract Patulin is a mycotoxin produced by several fungi, (Penicillium, Aspergillus, Byssochlamys). The main sources of patulin intake in human diet are apples, apple juice and apple nectar, and for this reason, apple based foods are monitored for the presence of this mycotoxin. Commission Regulation EC No 1881/2006 lays down maximum residue limits (MRLs) of 50 µg/kg in apple juice and cider, 25 µg/kg in solid apple products, and 10 µg/kg in products for infants and young children. In Serbia, maximum permitted amounts of patulin in fruit juices, reconstituted concentrated fruit juices and fruit nectars, as well as in solid apple products, including apple compote and apple puree, intended for direct human consumption are prescribed in the Regulation on maximum concentrations of certain contaminants in foodstuffs. This paper presents the LC-MS/MS method for quantitative determination of patulin in apple juice. Criteria for method validation were taken from Commission Decision 2002/657/EC. Linearity was confirmed in the concentration ranges of 0-100 µg/kg, with the limit of detection (LoD) of 9.85 µg/kg. The performance of the method was successfully verified by participating in a proficiency study.

scholarly journals Preparation and Application of Keggin Silicomolybdic acid Modified Electrode

2020 ◽  
Author(s):  
Miao Liu ◽  
Mingxuan Jia ◽  
Dong Hui Li
Keyword(s):  
Glassy Carbon Electrode ◽  
Modified Electrode ◽  
Glassy Carbon ◽  
Photoelectron Spectroscopy ◽  
Limit Of Detection ◽  
Differential Pulse ◽  
Carbon Electrode ◽  
X Ray ◽  
Linear Relationships

Abstract An innovative method for the determination of isoniazid tablets is studied through electrochemical method for the modification of glassy carbon electrode (GCE). Polyoxomolybdate, with stable structures, has not been widely used for the determination of substance. In this study, the mentioned polyoxomolybdate was characterized by Fourier transform infrared spectroscopy (FT-IR), UV-vis, X-ray diffraction (XRD), Atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS), and used to modify the glassy carbon electrode. The electrochemical performance of the polyoxomolybdate@GCE was investigated with cyclic voltammetry (CV) and differential pulse voltammetry (DPV), compared with the unmodified electrode, the proposed polyoxomolybdate modified electrode exhibited strong electro-catalytic activities towards isoniazid (INH). Under the optimized conditions, there was linear relationships between the DPV peak currents and the concentrations in the range of 1 × 10 -7 g/L to 3 × 10 -7 g/L for INH (R 2 = 0.9979), with the limit of detection (LOD) of 0.024 μg/L (based on S/N = 3). The modified electrode has proper reproducibility (RSD < 5%), stability, response time (< 3 min) and lifetime (up to 6 days).

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