scholarly journals Simultaneous Adsorptive Stripping Voltammetric Analysis of Heavy Metals at Graphenated Cupferron Pencil Rods

2022 ◽  
Author(s):  
Nelia Abraham Sanga ◽  
Nazeem Jahed ◽  
Zandile Leve ◽  
Emmanuel Iwuoha ◽  
Keagan Pokpas
Keyword(s):  
Metal Ion ◽  
Tap Water ◽  
Low Cost ◽  
Simultaneous Detection ◽  
Chelating Agent ◽  
Acetate Buffer Solution ◽  
Buffer Solution ◽  
Solution Ph ◽  
Voltammetric Analysis ◽  
Electrochemically Reduced Graphene Oxide

Abstract Electroanalysis of heavy metal ions in the presence of cupferron ligands has been extensively studied due to its ability to form stable metallic coordination complexes. Herein, electrochemically reduced graphene oxide (ERGO) sheets were for the first time employed in conjunction with low-cost, disposable pencil graphite rods and in-situ plated thin mercury films (HgF) for the simultaneous detection of Cd2+, Cu2+, Pb2+, and Zn2+ in the presence of cupferron as a chelating agent by square-wave adsorptive cathodic stripping voltammetry (SW-AdCSV). The technique is based on the catalytic reduction of adsorbed cupferron-metal ion complexes at the surface of the ERGO-HgF-PGE at 0.1 V for 60 s in 0.1 M acetate buffer solution (pH 4.6). Owing to the improved electronic and surface effects associated with ERGO inclusion, improved sensitivity was further achieved. Under optimized conditions, the ERGO-HgF-PGE showed a linear relationship from 20 to 200 µg.L-1 with detection limits below the US-EPA of 0.17 μg.L-1 , 0.02 μg.L-1 , 0.17 μg.L-1 and 0.14 μg.L-1 for Cd2+, Cu2+, Pb2+ and Zn2+, respectively at a deposition time of 60 s. The ERGO-HgF-PGE exhibited highly reproducible results with negligible intermetallic interferences and applied successfully to the determination of trace metals in tap water with satisfactory results.

Non-enzymatic determination of purine nucleotides using a carbon dot modified glassy carbon electrode

2019 ◽  
Vol 11 (30) ◽  
pp. 3866-3873 ◽  
Author(s):  
R. Karthikeyan ◽  
D. James Nelson ◽  
S. Abraham John
Keyword(s):  
Glassy Carbon ◽  
Low Cost ◽  
Phosphate Buffer Solution ◽  
Purine Nucleotides ◽  
Buffer Solution ◽  
Solution Ph ◽  
Carbon Dot ◽  
Enzymatic Determination ◽  
Sensitive Determination

Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.

Sorption Profile and Thermodynamic Characteristics of Nitrosonaphthol Functionalized Sorbent for Metal Ion Enrichment

2005 ◽  
Vol 70 (9) ◽  
pp. 1341-1356 ◽  
Author(s):  
Saima Q. Memon ◽  
Muhammad I. Bhanger ◽  
Muhammad Y. Khuhawar
Keyword(s):  
Metal Ion ◽  
Tap Water ◽  
Thermodynamic Characteristics ◽  
Chelating Agent ◽  
Standard Addition ◽  
Absorption Spectrometry ◽  
Sorption Data ◽  
Maximum Sorption ◽  
Styrene Divinylbenzene ◽  
Two Phases

A simple and reliable method has been developed using styrene-divinylbenzene-based polymeric material containing 1-nitroso-2-naphthol as chelating agent, to concentrate ultratrace amounts of Ni(II) and Cu(II) ions in aqueous samples. Sorption of both the ions on the new synthetic resin under static and dynamic conditions has been investigated. The sorption has been optimized with respect to pH, shaking and contact time of two phases. Maximum sorption has been achieved from solution of pH 5-8 after 8 min of agitation. Total saturation capacities were 516 ± 2 and 316 ± 2.5 μmol g-1 for Ni(II) and Cu(II) ions, respectively. The lowest concentration for quantitative recovery (98 ± 1%) is 1.33 and 5 ppb with the preconcentration factor of 750 and 200 for Ni(II) and Cu(II), respectively. Monitoring of the influence of diverse ions on the sorption of metal ions has revealed that phosphate, hydrogencarbonate and citrate reduce the sorption to some extent. Under optimum conditions the sorption data followed Langmuir, Freundlich, and Dubinin-Radushkevich isotherms. The kinetics and thermodynamics of sorption are studied in detail. The sorption procedure is utilized to preconcentrate these ions prior to their determination in tea, human hair, and tap water samples by atomic absorption spectrometry using direct and standard addition methods.

The use of photogenerated iodine in determination of the dibazol content in solid and liquid dosage formulations

2021 ◽  
Vol 87 (2) ◽  
pp. 19-24
Author(s):  
E. V. Turusova
Keyword(s):  
Generation Time ◽  
Quantitative Estimation ◽  
Potato Starch ◽  
Analytical Signal ◽  
Acetate Buffer Solution ◽  
Molar Ratio ◽  
Buffer Solution ◽  
Solution Ph ◽  
Solid Dosage

A rapid method for the determination of Dibazol (bendazol hydrochloride) in liquid and solid dosage forms (DF) has been developed. The method is based on converting the drug into an analytical form and titrating the physiologically active compound (PAC) with a solution of photogenerated iodine obtained by irradiation of an auxiliary solution containing potassium iodide, a mixture of sensitizers (sodium eosinate: fluorescein: auramine, taken in a molar ratio of 1:1:1) and an acetate buffer solution (pH 5.6). A decrease in the titrant content in the cell due to interaction with Dibazol was recorded by a decrease in the current in the amperometric circuit. Stabilization of the current in the circuit indicated the completeness of the reaction, thus providing for estimation of the PAC content in a DF. Further irradiation of the solution and measurement of the generation time required to replenish the titrant loss in the cell also ensure the quantitative estimation of the PAC content in the preparation. The method has been tested on solid dosage form and sterile solutions of Dibazol intended for intramuscular and intravenous administration. A slight effect of stabilizers (hydrochloric acid, ethanol) and auxiliary substances (potato starch) present in the DF on the photogeneration of the titrant was observed. The determined Dibazol content in solid and liquid DF falls within the range recommended by the order of the Ministry of Health of the Russian Federation (26.10.2015 No. 751n) and OFS.1.4.2.0009.15, which indicates that the quality of the drug meets the GMP standards. The linear dependence of the analytical signal on the Dibazol concentration is observed in the range of 13.5 – 134.7 mg for the drug «Dibazol-UBF, tablets, 20 mg». The calculated limits of Dibazol detection and quantitative determination by changes in the current strength and generation time are (4.71; 3.56) and (14.26; 10.77) mg, respectively. The use of developed technique in the analysis of drugs containing Dibazol reduces both the time of single determination due to the absence of the need for standardization of solutions, and the cost of a single analysis, since it does not require the use of expensive equipment and reagents.

Investigation of ORR Performances on Graphene/Phthalocyanine Nanocomposite in Neutral Medium

2019 ◽  
Vol 25 (6) ◽  
pp. 1416-1421 ◽  
Author(s):  
Moumita Mukherjee ◽  
Madhupriya Samanta ◽  
Gour P. Das ◽  
Kalyan K. Chattopadhyay
Keyword(s):  
Metal Ion ◽  
Low Cost ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Zinc Phthalocyanine ◽  
Neutral Medium ◽  
Neutral Solution ◽  
Solution Ph ◽  
Onset Potential

AbstractThe drive to replace scarce and expensive Pt-based electrocatalysts for oxygen reduction reaction (ORR) has led to the development of a group of electrocatalysts composed of transition-metal ion centers coordinated with four nitrogen groups (M-N4). Among these, metal phthalocyanines (MPcs), due to low cost of preparation, highly conjugated structure as well as high thermal and chemical stability, have received a great interest. The catalytic activity of MPcs can be improved by employing conducting supports. Here, in this report, we have solvothermally synthesized graphene-supported zinc phthalocyanine nanostructures, and their ORR kinetics and mechanism have been investigated in neutral solution (pH = 7) by using the rotating disk electrode technique. The as-synthesized nanocomposite followed a 4e− reduction pathway. The onset potential (−0.04 V versus Ag/AgCl) found in this work can be comparable with other state-of-the-art material, demonstrating good performance in neutral solution. The fascinating performance leads the nanocomposite material toward future energy applications.

scholarly journals Lead Ions Removal from Natural Water Samples by Nano-Mint Waste as Benign Low Cost Biosorbent

2018 ◽  
Vol 3 (2) ◽  
pp. 116-126
Author(s):  
Tamer H. A. Hasanin ◽  
Salwa A. Ahmed ◽  
Taghreed B. Ebrahim
Keyword(s):  
Natural Water ◽  
Water Samples ◽  
Metal Ion ◽  
Sea Water ◽  
Tap Water ◽  
Low Cost ◽  
Lead Removal ◽  
Lead Uptake ◽  
Natural Water Samples ◽  
Uptake Process

Nano mint waste (NMW) was used as a low-cost nano biosorbent and efficient Pb(II) remover. pH, contact time, biosorbent dose, and concentration of metal ion were optimized using batch technique to optimize maximum capacity of this new biosorbent. NMW was characterized using FT-IR, SEM, TEM, and XRD analyses. The experimental Pb(II) adsorption data by NMW were agreed with both Freundlich and Langmuir models with maximum boisorption capacity of 2.13 mmolg-1 (441.336 mgg-1). In addition, values of lead uptake at different time vaues was best fitted with the kinetic pseudo-second order model. It will be notable that, good data resulted from the kinetic experiments study confirmed a fast accessibility of the Pb(II) to the biosorbent surface, get to equilibrium within 30 seconds. On the other hand, it was observed that, the developed method, was investigated for measuring of Pb(II) with a certain spiked amounts in natural water samples as ground water (GW), sea water (SW), drinking tap water (DTW), natural drinking water (NDW), Nile River water (NRW) and waste water (WW). The good results obtained with high recovered quantitatively using batch experiments, without matrix interferences. Considering its cheap source, environmentally friendly, economic and fast uptake process, NMW can be used as benign nano biosorbent for lead removal from real water samples.

scholarly journals Fluorescence-Based On-Resin Detection of Three Model Proteases

Chemosensors ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 359
Author(s):  
David Milićević ◽  
Jan Hlaváč
Keyword(s):  
Fluorescent Dyes ◽  
Simultaneous Detection ◽  
Solid Support ◽  
Buffer Solution ◽  
Solution Ph ◽  
New Approach ◽  
Backbone Amide ◽  
Cleavable Peptide ◽  
Backbone Amide Linker ◽  
Competitive Activities

A new approach to on-resin detection of three model proteases (trypsin, chymotrypsin, and thrombin) has been developed, while at the same time already described methodology for simultaneous detection of two enzymes (trypsin and chymotrypsin) has been additionally generalized. Appropriate immobilized substrates, comprising specifically cleavable peptide sequences capped with fluorescent dyes, have been synthesized on Rink Amide PEGA resin or Amino PEGA resin modified with backbone amide linker (BAL). Resulting solid support-bound probes were then dispersed into Tris-HCl buffer solution (pH = 8.0) and subjected to enzymatic cleavage. Liberated fluorophores have been tracked by fluorescence measuring. The competitive activities of studied proteases towards the thrombin probe have been efficiently limited and controlled by employing a Bowman-Birk inhibitor into a system.

scholarly journals Simultaneous Detection of Dihydroxybenzene Isomers Using Electrochemically Reduced Graphene Oxide-Carboxylated Carbon Nanotubes/Gold Nanoparticles Nanocomposite

Biosensors ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 321
Author(s):  
Angélica Domínguez-Aragón ◽  
Rocio B. Dominguez ◽  
Erasto Armando Zaragoza-Contreras
Keyword(s):  
Carbon Nanotubes ◽  
Gold Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Tap Water ◽  
Simultaneous Detection ◽  
3D Network ◽  
Reduced Graphene ◽  
Electrochemically Reduced Graphene Oxide ◽  
Carboxylated Carbon Nanotubes

An electrochemical sensor based on electrochemically reduced graphene oxide (ErGO), carboxylated carbon nanotubes (cMWCNT), and gold nanoparticles (AuNPs) (GCE/ErGO-cMWCNT/AuNPs) was developed for the simultaneous detection of dihidroxybenzen isomers (DHB) hydroquinone (HQ), catechol (CC), and resorcinol (RS) using differential pulse voltammetry (DPV). The fabrication and optimization of the system were evaluated with Raman Spectroscopy, SEM, cyclic voltammetry, and DPV. Under optimized conditions, the GCE/ErGO-cMWCNT/AuNPs sensor exhibited a linear concentration range of 1.2–170 μM for HQ and CC, and 2.4–400 μM for RS with a detection limit of 0.39 μM, 0.54 μM, and 0.61 μM, respectively. When evaluated in tap water and skin-lightening cream, DHB multianalyte detection showed an average recovery rate of 107.11% and 102.56%, respectively. The performance was attributed to the synergistic effects of the 3D network formed by the strong π–π stacking interaction between ErGO and cMWCNT, combined with the active catalytic sites of AuNPs. Additionally, the cMWCNT provided improved electrocatalytic properties associated with the carboxyl groups that facilitate the adsorption of the DHB and the greater amount of active edge planes. The proposed GCE/ErGO-cMWCNT/AuNPs sensor showed a great potential for the simultaneous, precise, and easy-to-handle detection of DHB in complex samples with high sensitivity.

scholarly journals Response Surface Optimization of an Extraction Method for the Simultaneous Detection of Sulfamethoxazole and 17β-Estradiol in Soil

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1415
Author(s):  
Rui Song ◽  
Qincheng Chen ◽  
Lili Yan ◽  
Pinhua Rao ◽  
Peng Sun ◽  
...  
Keyword(s):  
Response Surface ◽  
High Performance ◽  
Detection Method ◽  
Simultaneous Detection ◽  
Animal Husbandry ◽  
Ultrasound Assisted Extraction ◽  
Buffer Solution ◽  
Solution Ph ◽  
Simultaneous Extraction ◽  
17Β Estradiol

Antibiotics and hormones widely exist in fertilizers and manures, which are excessively used in agriculture and animal husbandry. Considering their potential harm to the environment and human health, the detection of antibiotics and hormones has become a necessity. However, current methods find it difficult to simultaneously extract and detect antibiotics and hormones in soil and to maintain a high level of accuracy and a low cost. In this study, a straightforward, convenient, and simultaneous extraction and detection method of a representative antibiotic (sulfamethoxazole, SMZ) and hormone (17β-Estradiol, E2) in soil has been established. Ultrasound-assisted extraction (UAE) was used in the pretreatment process and high-performance liquid chromatography with the ultraviolet detector (HPLC-UV) method was then chosen in the detection process. By means of single factors and response surface experiments, optimal extraction conditions were a 41-mL buffer solution (pH 4.27) mixed with 1 g of soil sample, an ultrasonication time of 36 min, an ultrasonication temperature of 25 °C, and two extraction cycles. The detection limits of 0.3–10 μg/kg and quantification limits of 1–30 μg/kg have been obtained. Finally, the optimized simultaneous extraction and detection method was validated by three different real soil samples with recoveries ranging from 79.49% to 86.47%.

Comparative studies on adsorptive removal of heavy metal ions by biosorbent, bio-char and activated carbon obtained from low cost agro-residue

2015 ◽  
Vol 73 (2) ◽  
pp. 423-436 ◽  
Author(s):  
Çisem Kırbıyık ◽  
Ayşe Eren Pütün ◽  
Ersan Pütün
Keyword(s):  
Activated Carbon ◽  
Metal Ion ◽  
Low Cost ◽  
Chemical Activation ◽  
Second Order ◽  
Isotherm Models ◽  
Standard Entropy ◽  
Order Kinetic ◽  
Solution Ph ◽  
Pseudo Second Order

In this study, Fe(III) and Cr(III) metal ion adsorption processes were carried out with three adsorbents in batch experiments and their adsorption performance was compared. These adsorbents were sesame stalk without pretreatment, bio-char derived from thermal decomposition of biomass, and activated carbon which was obtained from chemical activation of biomass. Scanning electron microscopy and Fourier transform–infrared techniques were used for characterization of adsorbents. The optimum conditions for the adsorption process were obtained by observing the influences of solution pH, adsorbent dosage, initial solution concentration, contact time and temperature. The optimum adsorption efficiencies were determined at pH 2.8 and pH 4.0 for Fe(III) and Cr(III) metal ion solutions, respectively. The experimental data were modelled by different isotherm models and the equilibriums were well described by the Langmuir adsorption isotherm model. The pseudo-first-order, pseudo-second-order kinetic, intra-particle diffusion and Elovich models were applied to analyze the kinetic data and to evaluate rate constants. The pseudo-second-order kinetic model gave a better fit than the others. The thermodynamic parameters, such as Gibbs free energy change ΔG°, standard enthalpy change ΔH° and standard entropy change ΔS° were evaluated. The thermodynamic study showed the adsorption was a spontaneous endothermic process.

Effect of Sulfide Ions on the Corrosion Behaviour of Mild Steel in Acetate Buffer

1993 ◽  
Vol 58 (3) ◽  
pp. 547-554 ◽  
Author(s):  
Hyman H. Rehan ◽  
Said A. Salih ◽  
Hassan El-Daley ◽  
Ahmed G. Gad-Allah
Keyword(s):  
Mild Steel ◽  
Corrosion Behaviour ◽  
Acetate Buffer ◽  
Acetate Buffer Solution ◽  
Buffer Solution ◽  
Solution Ph ◽  
Dissolution Rates ◽  
Buffer Solutions ◽  
Sulfide Ions

The corrosion behaviour of mild steel was investigated in acidic acetate buffer solution using impendance and potential measurements. It was found that there are two dissolution rates resulting from the duplex nature of the formed oxides. The dissolution rates were found to depend on the dissolving acetate buffer solution pH and the dissolution temperature. In all cases, the film thickness was found to decrease with time of corrosion according to the relation Cm-1 = (Cm0)-1 - kdt1/2. It was found that addition of sulfide ions increases the dissolution rate and increases the rate of hydrogen evolution reaction but does not affect the mechanism of cathodic process. The role of sulfide ions on the corrosion behaviour of steel in acetate buffer solutions is revealed by the complex plane impendance analysis.

Sign in / Sign up

Export Citation Format

Share Document