A Novel Composite Voltammetric Sensor Based on Yttria-Stabilized Zirconia Doped with Neodymium-Carbon Black-Nafion Glassy Carbon Electrode for Metoprolol Determination

For the first time, a new composite voltammetric sensor based on yttria-stabilized zirconia doped with neodymium-carbon black-Nafion glassy carbon electrode (YSZNd-CB-Nafion/GCE) for the determination of metoprolol (MET) has been developed. The instrumental parameters and supporting electrolyte were optimized. For 105 s accumulation time, linearity was achieved in the range of 0.01 to 0.2 µM. The limit of detection (for 105 s accumulation time) was equal to 2.9 nM (2 µg/L), and was the best result in comparison to other voltametric sensors. The reproducibility of the metoprolol signal presented as relative standard deviation (RSD) was equal to 1.9% (n = 7). Additionally, our electrode is characterized by high stability, is easy to use, and has a short preparation time. The proposed sensor was found useful for MET determination in plasma and urine, as well as for pharmaceutical samples, with a good recovery parameter (96-108%). Flow injection analysis (FIA) with amperometric detection was also performed for MET determination. The recovery was calculated and was in the range 101-103%, suggesting that the proposed material may be applied in flow injection analysis.

Advances of Drugs Electroanalysis Based on Direct Electrochemical Redox on Electrodes: A Review

The strong development of mankind is inseparable from the proper use of drugs, and the electroanalytical research of drugs occupies an important position in the field of analytical chemistry. This review mainly elaborates the research progress of drugs electroanalysis based on direct electrochemical redox on various electrodes for the recent decade from 2011 to 2021. At first, we summarize some frequently used electrochemical data processing and electrochemical mechanism research derivation methods in the literature. Then, according to the drug therapeutic and application/usage purposes, the research progress of drugs electrochemical analysis is classified and discussed, where we focus on drugs electrochemical reaction mechanism. At the same time, the comparisons of electrochemical sensing performance of the drugs on various electrodes from recent studies are listed, so that readers can more intuitively compare and understand the electroanalytical sensing performance of each modified electrode for each of the drug. Finally, this review discusses the shortcomings and prospects of the drugs electroanalysis based on direct electrochemical redox research.

Sonochemical synthesis of novel thermo-responsive polymer and tungsten dioxide composite for the temperature-controlled reversible "on-off" electrochemical detection of β-Blocker metoprolol

Thermo-responsive polymer nanocomposite based on poly (styrene-co-N-isopropylacrylamide) hybrid tungsten dioxide (WO₂@PS-co-PNIPAM) was synthesized by a facile ultrasonic irradiation (Frequency; 20 kHz, power; 180 W, calorimetrically determined power; 5.73 W in the bath, and Type; probe) method in the presence of water as inisolv. The as-synthesized WO₂@PS-co-PNIPAM modified glassy carbon electrode (WO₂@PS-co-PNIPAM/GCE) was acting as a reversibly switched detection for the electrooxidation of metoprolol (MTP), with the thermal stimuli response of the PNIPAM. In below lower critical solution temperature (LCST), the PS-co-PNIPAM expanded to embed the electroactive sites of WO₂, and the MTP could not proceed via the polymer to attain electronic transfer, indicating the "off" state. Rather, in above LCST, the PS-co-PNIPAM shrank to reveal electroactive sites and expand cyclic voltammetric background peak currents, the MTP was capable to undergo electro-oxidation reaction usually and produce the response current, indicating "on" state. Additionally, the proposed sensor had excellent sensitivity (2.21 µA µM^-1 cm^-2), wide dynamic range (0.05-306 µM), and a low limit of detection of 0.03 µM for MTP. Intriguingly, the fabricated sensor demonstrates the good selectivity towards the detection of MTP among the possible interfering compounds. Eventually, the WO₂@PS-co-PNIPAM/GCE has been utilized in the analysis of MTP in human blood serum samples.

A polyoxy group branched diazo dye as an alternative material for the fabrication of an electrochemical epinephrine sensor

A polyoxy group attached diazo dye on an electrode surface improved the voltammetric response of epinephrine.

Electrochemistry and determination of cefdinir by voltammetric and computational approaches

The oxidation and reduction behavior of cefdinir (CEF) was studied by experimental methods and computational calculations at B3LYP/6–31+G (d)//AM1. Voltammetric studies were carried out based on two irreversible reduction peaks at approximately −0.5 and −1.2 V on a hanging mercury drop electrode (HMDE) and on one irreversible oxidation peak at approximately 1.0 V on a glassy carbon electrode (GCE) versus Ag/AgCl, KCl (3.0M) in Britton–Robinson (BR) buffer at pH 4.2 and 5.0, respectively. Differential pulse adsorptive stripping voltammetric methods have been developed and validated for determination of CEF in different samples. The linear range was established as 0.25–40.0 μM for HMDE and 0.40–10.0 μM for GCE. Limit of quantification was calculated to be 0.20 and 0.26 μM for HMDE and GCE, respectively. These methods were successfully applied to assay the drug in tablets and human serum with good recoveries between 92.7% and 107.3% having relative standard deviation less than 10%.

A novel nitrogen-containing compound with D-π-A structure: theoretical and experimental study

2-(2-Hydroxy-styryl)-4,6-dimethyl-1,3,5-triazine (P1), a novel compound with D-π-A structure, possesses a variety of isomers. Density functional theory calculations were employed to explore the isomerization mechanisms of its various isomers at the 6-311+G** level. The calculated results show that the phenol configurations of compound P1 are more stable than the quinoid configurations, whether they exist as monomers, complexes, with methanol or dimers. The most stable structure of compound P1 was used to calculate the UV-vis and fluorescence spectra. To validate the calculated results, the title compound was synthesized and characterized by 1H NMR and 13C NMR techniques. The measured absorption and fluorescence spectra of P1 in methanol and N,N-dimethylformamide are in good agreement with the calculated ones.