scholarly journals NEW VOLTAMMETRIC METHOD FOR DETERMINATION OF PHENANTHRENE IN GROUNDWATER

2019 ◽  
Vol 16 (33) ◽  
pp. 169-177
Author(s):  
A. P. M. FERREIRA ◽  
E. J. N. TEIXEIRA ◽  
I. M. de OLIVEIRA ◽  
H. de A. PINHEIRO ◽  
A. L. B. MARQUES
Keyword(s):  
Differential Pulse ◽  
Good Alternative ◽  
Pulse Mode ◽  
Average Concentration ◽  
Good Precision ◽  
Average Value ◽  
Analytical Curve ◽  
Water Well ◽  
Optimized Conditions

This work proposes a new method for the determination of phenanthrene (FEN) in aqueous medium with a cobalt phthalocyanine modified glassy carbon electrode (ECV / CoPc), using Differential Pulse Voltammetry (VPD), whose oxidation of FEN occurs between 1,3 and 1,4 V. The electrode was modified with a 1x10-3 mol∙L-1 CoPc methanolic solution containing 10% Nafion. For voltammetric measurements in Differential Pulse mode, an amplitude of 0.7V and a scan rate of 0.04V s-1 were used. Experimental parameters were optimized for the purpose of determination of FEN in groundwater collected in a water well of a São Luis-MA fuel station. Under these optimized conditions, an analytical curve was obtained in the 0.49 to 2,4 μM concentration range, with a detection limit of 1,2 x 10-10 mol∙L-1. The method was applied to a real groundwater sample from a water well located at a fuel station, and an average concentration of 0.037 μM FEN was found (n = 5), presenting a variation coefficient of 0.88, indicating good precision. Accuracy was assessed by the recovery test, whose average value was 99.9%. These results indicate that the proposed procedure is a good alternative for the analysis of FEN in natural water.

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 Selective Determination of Iron(III) in Sea Water by Gold Nanoparticles Self-assembled with N-carboxyl- L-cysteine

2014 ◽  
Vol 17 (1) ◽  
pp. 001-004 ◽  
Author(s):  
Benzhi Liu ◽  
Min Wang
Keyword(s):  
Gold Nanoparticles ◽  
Detection Limit ◽  
Sea Water ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Operational Parameters ◽  
Selective Determination ◽  
Self Assembled ◽  
Optimized Conditions

Application of gold nanoparticles self-assembled with N-carboxyl- L-cysteine for the determination of iron(III) was investigated. Differential pulse adsorptive stripping voltammetry was used to detect iron(III). Various operational parameters were investigated and discussed in terms of their effects on the measurement signals. A linear range from 0.1 nM to 1.8 nM with a detection limit of 0.03 nMwas obtained under optimized conditions. The applicability of the method was successfully tested by determination of iron(III) in sea water samples.

scholarly journals Carbon ceramic electrode incorporated with zeolite ZSM-5 for determination of Piroxicam

2010 ◽  
Vol 8 (1) ◽  
pp. 155-162 ◽  
Author(s):  
Karim Asadpour-Zeynali ◽  
Mir Majidi ◽  
Mitra Zarifi
Keyword(s):  
Modified Electrode ◽  
Pharmaceutical Formulations ◽  
Differential Pulse ◽  
Solution Ph ◽  
Carbon Ceramic Electrode ◽  
Experimental Parameters ◽  
Voltammetric Behavior ◽  
Carbon Ceramic ◽  
Optimized Conditions

AbstractA new chemically modified electrode is constructed based on carbon ceramic electrode incorporated with zeolite ZSM-5. Voltammetric behavior of piroxicam at the carbon ceramic zeolite modified electrode (CCZME) was investigated. The modified electrode exhibited catalytic activity toward the electrooxidation of piroxicam. Experimental parameters such as solution pH, scan rate, concentration of piroxicam and zeolite amount were studied. It has been shown that using the CCZME, piroxicam can be determined by differential pulse voltammetry (DPV) and hydrodynamic amperometry (HA). Under the optimized conditions the calibration plots are linear in the concentration ranges of 0.20–25.00 and 0.20–50.10 μM with limit of detections of 0.65 and 0.29 μM for DPV and HA, respectively. The modified electrode with DPV and HA methods was successfully applied for analysis of piroxicam in pharmaceutical formulations. The results were favorably compared to those obtained by the spiked method. The results of the analysis suggest that the proposed method has promise for the routine determination of piroxicam in the products examined.

Synthesis of Co/TiO2 Nanocomposite and its Use in Construction of a Sensitive and Selective Sensor for Determination of Ciprofloxacin

2013 ◽  
Vol 829 ◽  
pp. 563-567 ◽  
Author(s):  
Mojtaba Shamsipur ◽  
Mohammad Bagher Gholivand ◽  
Sara Dehdashtian ◽  
Mostafa Feyzi ◽  
Fataneh Jafari
Keyword(s):  
Sol Gel ◽  
Differential Pulse ◽  
Gravimetric Analysis ◽  
Carbon Paste ◽  
Ftir Spectrometry ◽  
Pulse Voltammetry ◽  
Optimized Conditions ◽  
Paste Electrode ◽  
Selective Sensor

The Co/TiO2 nanocomposite was synthesized by a modified sol-gel method. The surface structure and composition of nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction analysis (XRD), Fourier transform infrared (FTIR) spectrometry, thermal gravimetric analysis (TGA) and N2 physisorption. A carbon paste electrode (CPE) modified with Co/TiO2 nanocomposite was prepared and used for low level determination of antibiotic ciprofloxacin (CF) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimized conditions, the modified electrode exhibited a linear response over the concentration range of 0.1 to 70 μM CF, with a detection limit of 0.03 μM. The proposed sensor was applied to the CF determination in serum and urine samples.

scholarly journals A novel dopamine electrochemical sensor based on La3+/ZnO nanoflower modified graphite screen printed electrode

2019 ◽  
Vol 9 (3) ◽  
pp. 187-195 ◽  
Author(s):  
Somayeh Tajik ◽  
Hadi Beitollahi ◽  
Mohammad Reza Aflatoonian
Keyword(s):  
Modified Electrode ◽  
Phosphate Buffer Solution ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Screen Printed Electrode ◽  
Buffer Solution ◽  
Optimized Conditions ◽  
Screen Printed

Flower-like La3+/ZnO nanocomposite was facile synthesized. A simple and ultrasensitive sensor based on graphite screen printed electrode (SPE) modified by La3+/ZnO nanoflower was developed for the electrochemical determination of dopamine. The electrochemical behavior of dopamine was studied in 0.1 M phosphate buffer solution (PBS) using cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Compared with the unmodified graphite screen printed electrode, the modified electrode facilitates the electron transfer of dopamine, since it notably increases the oxidation peak current of dopamine. Also, according to CV results the maximum oxidation of dopamine on La3+/ZnO/SPE occurs at 150 mV which is about 140 mV more negative compared with unmodified SPE. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range from 0.15 to 300.0 μM, with a detection limit of 0.08 μM (S/N = 3). The proposed sensor exhibited a high sensitivity, good stability and was successfully applied for dopamine determination in dopamine ampoule, with high recovery.

Voltammetric determination of 1,2-diaminoanthraquinone using carbon paste electrode

2011 ◽  
Vol 76 (8) ◽  
pp. 1033-1041
Author(s):  
Jiří Zima ◽  
Veronika Tinková ◽  
Joseph Wang ◽  
Jiří Barek
Keyword(s):  
River Water ◽  
Direct Current ◽  
Carbon Paste Electrode ◽  
Differential Pulse ◽  
Voltammetric Determination ◽  
Carbon Paste ◽  
Limit Of Determination ◽  
Optimized Conditions ◽  
Paste Electrode

Direct current (DC) voltammetry and differential pulse (DP) voltammetry using a carbon paste electrode (CPE) have been used for the determination of trace amounts of ecotoxic 1,2-diaminoanthraquinone (DAAQ). The limit of determination (LD) of DAAQ for DC voltammetry was 2 × 10–6 mol l–1, and for DP voltammetry 2 × 10–7 mol l–1 under the optimized conditions in a mixed Britton–Robinson buffer pH 12 and methanol (1:9) medium. Adsorptive accummulation of the analyte on the surface of CPE decreased the limit of determination to 2 × 10–8 mol l–1 for DP voltammetry. Practical applicability of these newly developed methods was verified on model samples of river water.

Improved Polarographic Method for Determination of Glyphosate Herbicide in Crops, Soil, and Water

1985 ◽  
Vol 68 (1) ◽  
pp. 76-79
Author(s):  
Hakon O Friestad ◽  
Jan O Bronstad
Keyword(s):  
Limit Of Detection ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Good Precision ◽  
Pulse Polarography ◽  
Basic Resin ◽  
Glyphosate Herbicide ◽  
Selection Of ◽  
Better Than

Abstract A prior method for determination of glyphosate in water samples has been modified to accommodate samples of crops and soils. Differential pulse polarography as the determinative step enables analysis in an aqueous medium, which is important during extraction of this compound. Residues are cleaned up and concentrated by ion exchange on a strong basic resin in OH- form. The method is rapid, is applicable to a relatively broad selection of sample types, and gives recoveries consistently better than 60% with good precision. The main shortcoming of the method is that the limit of detection of 0.5-1.0 ppm may sometimes be inadequate. The metabolite, aminomethyl phosphonic acid, is not detected.

Determination of Unsaponifiable Residues in Milk

1966 ◽  
Vol 49 (5) ◽  
pp. 959-963
Author(s):  
Robert T Teague ◽  
Frank L Joe
Keyword(s):  
Unsaponifiable Matter ◽  
Column Chromatography ◽  
Mineral Oil ◽  
Good Precision ◽  
Average Value ◽  
Milk Samples ◽  
Water Washing ◽  
Ether Solvents

Abstract Unsaponifiable residues are determined in milk samples by the following procedure: oily drug bases and fats are extracted with iso-octane (rather than the usual mixed ether solvents) in an alkaline alcohol-acetone mixture; this extract is concentrated and the fatty constituents are saponified with KOH. The unsaponifiable matter is then re-extracted with iso-octane and the residual soaps and extraneous constituents are removed by water washing and column chromatography. Mineral oil added at levels of 12–404 ppm to milk samples was quantitatively recovered, with an average value of 98%. Unsaponifiable matter in market milk was also determined; results demonstrated good precision between duplicate analyses. Milk-out studies were performed to determine the rate of diffusion and dissipation of infused formulations.

scholarly journals Analysis of radon concentration and gamma dose rate in residential houses of Ambon and Seram Islands, Maluku

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
WAHYUDI WAHYUDI ◽  
ILMA DWI WINARNI ◽  
MUJI WIYONO ◽  
KUSDIANA KUSDIANA
Keyword(s):  
Radon Concentration ◽  
Radiation Safety ◽  
Track Detector ◽  
Average Concentration ◽  
Nuclear Track Detector ◽  
Environmental Radiation ◽  
Average Value ◽  
Naoh Solution ◽  
Radon Concentrations

Radon concentration analysis in the residential houses on Ambon and Seram Island - Maluku through the passive method using the CR-39 nuclear track detector has been studied. The CR-39 nuclear track detector was installed inside the residential houses for 3 months. After finishing the exposure, the detector was taken and etched using 6.25 N NaOH solution. The nuclear track of radon in the CR-39 was read by a microscope with 400 times magnification. From the results of reading the track, determination of radon concentration in the houses was calculated. The results of the analysis showed that radon concentrations in the residential houses of Ambon and Seram Islands, Maluku at the low level were in the range of 2.56 ± 0.18 Bq/m3 to 59.65 ± 4.22Bq/m3 with an average value of 28.42 ± 1.98 Bq/m3. The average concentration of radon is still below the average radon concentration in the world of 50 Bq/m3. The value of dose received by the population due to exposure of radon and gamma radiation in the range of 0.90-1.44 mSv/year. There is a positive correlation between radon concentration value and total radiation doses received by the population for a year. This data can be used in the study of radiation safety for the Ministry of Health and as a contribution to Indonesia in the international community about monitoring environmental radiation from radon concentrations in residential houses

Determination of Verapamil in Exhaled Breath Condensate by Using Microextraction and Liquid Chromatography

2019 ◽  
Vol 15 (5) ◽  
pp. 535-541 ◽  
Author(s):  
Fariba Pourkarim ◽  
Ali Shayanfar ◽  
Maryam Khoubnasabjafari ◽  
Fariborz Akbarzadeh ◽  
Sanaz Sajedi-Amin ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Exhaled Breath Condensate ◽  
Exhaled Breath ◽  
Good Precision ◽  
Dispersive Liquid Liquid Microextraction ◽  
Breath Condensate ◽  
Liquid Microextraction

Background:Developing a simple analysis method for quantification of drug concentration is one of the essential issues in pharmacokinetic and therapeutic drug monitoring studies.Objective:A fast and reliable dispersive liquid-liquid microextraction procedure was employed for preconcentration of verapamil in exhaled breath condensate (EBC) samples and this was followed by the determination with high-performance liquid chromatography-ultraviolet detection.Methods:A reverse-phase high-performance liquid chromatography (RP-HPLC) combined with a dispersive liquid-liquid microextraction method (DLLME) was applied for quantification of verapamil in the EBC samples. The developed method was validated according to FDA guidelines.Results:Under the optimum conditions, the method provided a linear range between 0.07 and 0.8 µg.mL-1 with a coefficient of determination of 0.998. The intra- and inter-day relative standard deviation and relative error values of the method were below 15%, which indicated good precision and accuracy. The proposed method was successfully applied for the analysis of verapamil in two real samples with concentrations of 0.07 and 0.09 µg.mL-1.Conclusion:The established HPLC-UV-DLLME method could be applied for the analysis of verapamil in human EBC samples.

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