Iodide-selective carbon paste electrodes based on recently synthesized Schiff base complexes of Fe(III)

2001 ◽  
Vol 450 (1-2) ◽  
pp. 37-44 ◽  
Author(s):  
Mojtaba Shamsipur ◽  
Ahmad Soleymanpour ◽  
Morteza Akhond ◽  
Hashem Sharghi ◽  
Mohammad Ali Naseri
Author(s):  
Maria Fernanda M. Ribeiro ◽  
Erica N. Oiye ◽  
Juliana M. T. Katayama ◽  
José W. C. Junior ◽  
Edward R. Dockal ◽  
...  

In recent years, practical, inexpensive, and highly specific electroanalytical methods based on modified electrodes have been increasingly developed for forensic science. Simple modification of the carbon paste electrode with Schiff base complexes has become a promising strategy to detect and quantify narcotics. In this context, we aimed to develop voltammetric methods to quantify lysergic acid diethylamide (LSD) by using a carbon paste electrode modified with the complex [UO2(Ac-ophen)]·H2O. The use of an aqueous solution of KCl as supporting electrolyte makes the methodology less polluting, which contrasts with methods that still employ toxic solvents. The developed method for Differential Pulse Voltammetry provides a linear response at various concentrations of LSD and affords analytical curves with standard deviation, detection, and quantification limits around 2.45, 0.625, and 2.08 μmol L-1, respectively. The recovery values of 103 and 108% prove that the developed method is suitable for application in forensic science.


Author(s):  
Ana Beatriz da Silva ◽  
Alex Castro ◽  
Marcelo de Oliveira

In this article we have studied the electrochemical behavior of cocaine hydrochloride on the surface of a carbon paste electrode chemically modified with a Schiff base complex, namely [FeIII(salen)], [ZrOII(salen)], or [NiII(salen)], during voltametric analyses. Among the tested complexes, [NiII(salen)] provided amperometric and thermal stability and it was only degraded at temperatures above 400 ºC. To prepare the cocaine hydrochloride was used hydrochloric acid (HCl 1 mol L-1) after we tested the electrode, the HCl did not cause electrode passivation. In this study we can see that the voltammetric analyses revealed a satisfactory result, that the peak current obtained between 0.1 and 0.2 V (vs. Ag/AgCl) varied linearly with cocaine hydrochloride concentration and the average amperometric sensitivity, the LOD, and the LOQ were 5.5 μmol L-1, 0.945 μmol L-1, and 3.16 μmol L-1, respectively.


2008 ◽  
Vol 19 (5) ◽  
pp. 749-755 ◽  
Author(s):  
Mahmut Ulusoy ◽  
Hasan Karabıyık ◽  
Rafet Kılınçarslan ◽  
Muhittin Aygün ◽  
Bekir Çetinkaya ◽  
...  

2021 ◽  
Vol 1232 ◽  
pp. 129975
Author(s):  
Murat Tuna ◽  
Salih Zeki Yildiz ◽  
Gulnur Arabaci ◽  
Zeynep Denli ◽  
Nagihan Çaylak Delibaş ◽  
...  

2021 ◽  
Vol 19 (1) ◽  
pp. 772-784
Author(s):  
Moamen S. Refat ◽  
Ahmed Gaber ◽  
Walaa F. Alsanie ◽  
Mohamed I. Kobeasy ◽  
Rozan Zakaria ◽  
...  

Abstract This article aimed at the synthesis and molecular docking assessment of new diimine Schiff base ligand, namely 2-((E)-(2-((Z)-2-(4-chlorophenyl)-2-hydroxyvinyl)hydrazono) methyl)-6-methoxyphenol (methoxy-diim), via the condensation of 1-(4-chloro-phenyl)-2-hydrazino-ethenol compound with 2-((E)-(2-((Z)-2-(4-chlorophenyl)-2-hydroxy vinyl) hydrazono)methyl)-6-methoxyphenol in acetic acid as well as the preparation of new binuclear complexes of Co(ii), Ni(ii), Cu(ii), and Zn(ii). The following synthesized complexes were prepared in a ratio of 2:1 (metal/ligand). The 1H-NMR, UV-Vis, and FTIR spectroscopic data; molar conductivity measurements; and microanalytical, XRD, TGA/DTG, and biological studies were carried out to determine the molecular structure of these complexes. According to the spectroscopic analysis, the two central metal ions were coordinated with the diamine ligand via the nitrogen of the hydrazine and oxygen of the hydroxyl groups for the first metal ions and via the nitrogen of the hydrazine and oxygen of the phenol group for the second metal ions. Molecular docking for the free ligand was carried out against the breast cancer 3hb5-oxidoreductase and the 4o1v-protein binding kidney cancer and COVID-19 protease, and good results were obtained.


Chemosensors ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 52
Author(s):  
Nermine V. Fares ◽  
Passant M. Medhat ◽  
Christine M. El Maraghy ◽  
Sherif Okeil ◽  
Miriam F. Ayad

Two inexpensive and simple methods for synthesis of carbon nanodots were applied and compared to each other, namely a hydrothermal and microwave-assisted method. The synthesized carbon nanodots were characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis), photoluminescence (PL), Fourier transform-infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synthesized microwave carbon nanodots had smaller particle size and were thus chosen for better electrochemical performance. Therefore, they were used for our modification process. The proposed electrodes performance characteristics were evaluated according to the IUPAC guidelines, showing linear response in the concentration range 10−6–10−2, 10−7–10−2, and 10−8–10−2 M of tobramycin with a Nernstian slope of 52.60, 58.34, and 57.32 mV/decade for the bare, silver nanoparticle and carbon nanodots modified carbon paste electrodes, respectively. This developed potentiometric method was used for quantification of tobramycin in its co-formulated dosage form and spiked human plasma with good recovery percentages and without interference of the co-formulated drug loteprednol etabonate and excipients.


Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3150
Author(s):  
Fatehy M. Abdel-Haleem ◽  
Sonia Mahmoud ◽  
Nour Eldin T. Abdel-Ghani ◽  
Rasha Mohamed El Nashar ◽  
Mikhael Bechelany ◽  
...  

Levofloxacin (LF) is a medically important antibiotic drug that is used to treat a variety of bacterial infections. In this study, three highly sensitive and selective carbon paste electrodes (CPEs) were fabricated for potentiometric determination of the LF drug: (i) CPEs filled with carbon paste (referred to as CPE); (ii) CPE coated (drop-casted) with ion-selective PVC membrane (referred to as C-CPE); (iii) CPE filled with carbon paste modified with a plasticizer (PVC/cyclohexanone) (referenced as P-CPE). The CPE was formulated from graphite (Gr, 44.0%) and reduced graphene oxide (rGO, 3.0%) as the carbon source, tricresyl phosphate (TCP, 47.0%) as the plasticizer; sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (St-TFPMB, 1.0%) as the ion exchanger; and levofloxacinium-tetraphenylborate (LF-TPB, 5.0%) as the lipophilic ion pair. It showed a sub-Nernstian slope of 49.3 mV decade−1 within the LF concentration range 1.0 × 10−2 M to 1.0 × 10−5 M, with a detection limit of 1.0 × 10−5 M. The PVC coated electrode (C-CPE) showed improved sensitivity (in terms of slope, equal to 50.2 mV decade−1) compared to CPEs. After the incorporation of PVC paste on the modified CPE (P-CPE), the sensitivity increased at 53.5 mV decade−1, indicating such improvement. The selectivity coefficient (log KLF2+,Fe+3pot.) against different interfering species (Na+, K+, NH4+, Ca2+, Al3+, Fe3+, Glycine, Glucose, Maltose, Lactose) were significantly improved by one to three orders of magnitudes in the case of C-CPE and P-CPE, compared to CPEs. The modification with the PVC membrane coating significantly improved the response time and solubility of the LF-TPB within the electrode matrix and increased the lifetime. The constructed sensors were successfully applied for LF determination in pharmaceutical preparation (Levoxin® 500 mg), spiked urine, and serum samples with high accuracy and precision.


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