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In this work, platinum nanoparticles (Pt) decorated on a spinel group, zinc cobalt oxide (ZnCo2O4) 3-D flower was intended to detect caffeine electrochemical sensor. Pt particles were used to enhance the performance of hydrothermally prepared 3-D ZnCo2O4 flower. So Pt nanoparticles were decorated on each thin nanosheet of self-assembled 3-D flower-like ZnCo2O4. The thin transparent nanosheet of the ZnCo2O4 flower will benefit electrochemical sensors by simplifying its ion exchange. Therefore, Pt@ZnCo2O4 shows an excellent electrochemical conductivity, which promotes the caffeine-based sensor's rapid electrochemical oxidation. Using amperometric i-t at an applied potential of 1.45 V, Pt@ZnCo2O4 modified electrode shows widespread of two linear ranges (0.05 to 265.55 μM and 295.55 to 757.55 μM) with a low detection limit (0.0114 and 0.01657 μM) and high sensitivity (3.419 and 1.862 μA μM−1 cm−2). Moreover, good results were obtained for the real-time detection of caffeine in sugar-free cola beverage and energy drink samples. Henceforth, the developed method could be an ideal way to detect caffeine in real samples.

Trace level detection of drugs and hazardous analytes is more critical in electrochemical sensor. In this work, a simple sonochemical-assisted synthesis of Bismuth-EDTA complex/GO flakes was achieved and was developed to analyze mesalazine (MSA) sensing. The 3D hollow bricks were obtained for the Bi-EDTA complex without PVP. Surprisingly, PVP influenced the formation of broken glass-like structured for PVP with Bi-EDTA complex. Bi-EDTA complex modified GCE was developed to determine the role of PVP and its activity in electrochemical sensors. The results obtained by modifying the electrode Bi-EDTA complex with PVP showed good electrochemical performance compared to bare and other controls like GO and Bi-EDTA complex without PVP. The synergetic effect and high electroactive sites of Bi-EDTA complex/GO modified sensor implied low LOD (0.55 nM) and wide linear range from 0.005–585 µM. Furthermore, Bi-EDTA complex/GO showed an excellent selectivity in sensing MSA. Moreover, the Bi-EDTA complex exhibits advantages such as good stability, reproducibility, and repeatability. The modified Bi-EDTA complex/GCE sensor has been practically done to determine trace levels of MSA in human urine samples containing mesalamine tablets with satisfactory results.

The fabrication of transition metal ion-influenced titanates over the superficial region of glassy carbon electrodes (GCEs) can stimulate the electrocatalytic activity owing to the surface functionalization abilities of titanates, improved electron transfer rates, higher active surface areas, etc. In this regard, we have fabricated different metal titanates (CoTiO3, NiTiO3, and ZnTiO3) on GCEs for the nanomolar-level simultaneous detection of the hazardous poultry feed antibiotics furazolidone (FZD) and dimetridazole (DMZ). Different microscopic and spectroscopic techniques were used to characterize the physicochemical properties of the synthesized titanates. From these studies, the different formed metal titanates were pure without any impurities, and NiTiO3 showed more excellent electrochemical performance than the other two titanates. For simultaneous detection, CV and DPV techniques were utilized with working potentials (vs. Ag/AgCl) from 0 to −1 V and −0.2 to −0.9 V. For FZD and DMZ, well-defined and distinguishable peaks were obtained at around −0.45 V and −0.73 V. Our advanced sensor using a NiTiO3-modified electrode provided a decent linear range of 0.01 to 76 μM for FZD and DMZ with appreciable detection limits (4.082 and 7.059 nM) and sensitivities (0.589 and 1.019 μA μM−1 cm−2). Furthermore, real-time analysis carried out using chicken and sparrow egg samples led to good recovery results.

A metal-free C-N bond cleavage of amide functionality has been reported for the efficient and rapid synthesis of thioester in a simple flow system. The feasibility of this method has been investigated with various aliphatic and aromatic thiols with N-acylamide derivatives to deliver the corresponding thioesters. The fruitful outcome of this process includes good to excellent yields, broad functional group compatibility and can afford the thioesters in just 40 s.

Flufenamic acid (FFA) has anti-inflammatory, analgesic and antipyretic properties. We describe herein the preparation of a nanoribbon-like copper metal–organic framework (CuMOF) with an average length of 10 ± 5 μm and a width of 100 ± 50 nm via a simple hydrothermal approach. An amperometric sensor based on the activated carbon (AC)-supported ribbon-like CuMOF-modified electrode has been constructed for the detection of FFA. The AC–CuMOF nanostructure was characterized using scanning electron microscopy (SEM), electron diffraction X-ray spectroscopy (EDX) and X-ray diffraction (XRD) spectroscopy techniques. The peak current confirmed the excellent electrooxidation of FFA at the AC–CuMOF-modified glassy carbon electrode (GCE) and peak potential values resulting from cyclic voltammetry (CV) and amperometric (i–t) studies. The estimated values of the linear range (0.01 μM to 2210 μM), limits of detection (1.09 nM) and quantification revealed the enhanced electrocatalytic activity of the AC–CuMOF-modified GCE as compared to only CuMOF and AC. AC–CuMOF/GCE also possesses better repeatability and reproducibility along with good sensitivity (13.75 μA μM−1 cm−2). Even in the presence of other common potential interferents, our fabricated electrode displayed high selectivity towards FFA. The practicability demonstration of our sensor has been done in urine samples. Thus, AC–CuMOF/GCE can be a crucial platform in the determination of FFA.

Development of electrochemical sensor for sensing hazardous and toxic analytes are much needed. In this work, we report a Zinc oxide (ZnO) and zinc cobalt oxide (ZnCo2O4) forming a nano-heterostructure (NH) decorated on a glassy carbon electrode (GCE) for the electrochemical detection of furaltadone (FLT). ZnO-ZnCo2O4 NH was prepared using a hydrothermal assisted one-step calcination process. Physicochemical characterization of the synthesized ZnO-ZnCo2O4 was carried out using the XRD, XPS, and FESEM. The electrochemical performances were studied using electrochemical impedance spectroscopy and voltammetry techniques like cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in phosphate buffer pH-7. A newly developed FLT sensor based on the ZnO-ZnCo2O4 NH modified electrode showed a respectable linear range (0.01 to 4.68 μM and 15 to 100 μM) with a lower detection limit (1.46 nM and 34.1 nM), and higher sensitivity (24.4 and 0.72 μA.μM−1.cm−2). Further, ZnO-ZnCo2O4 NH modified electrode displayed excellent selectivity among other common interfering species found in fish tissues. Additionally, our advanced sensor demonstrated good reproducibility, repeatability, and stability. The developed sensor's practicability was successfully applied in analyzing FLT in fish tissues, and compared with HPLC results.

Trace level evaluation in analysis is an important step to construct a viable sensor. Here, the proposed furazolidone (FZD) sensor was developed electrochemically using an SnS2-SnO2/graphene composite. The formation of the SnS2-SnO2/graphene composite was confirmed by physical characterizations such as X-ray crystallography (XRD), Scanning Electron Microscope (SEM), and Fourier Transform InfraRed (FT-IR) Spectroscopy. The newly synthesized SnS2-SnO2/graphene composite was drop-casted on a glassy carbon electrode (GCE) surface to investigate the electrochemical oxidation of FZD using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods with the best working potential at −0.516 (vs. Ag/AgCl) in 0.1 M PB solution (pH 7.0). Using CV, different modified electrodes, different addition, scan rates, and pH studies were investigated to study peak current effects. The obtained DPV results at the SnS2-SnO2/graphene composite exhibited a lower limit of detection (LOD) (1.42 nM), good linear range, high selectivity, short-time response (˂1 s), better repeatability, reproducibility, and enduring stability. In addition, the fabricated SnS2-SnO2/graphene/GCE was used to determine the FZD in a commercially available furoxone tablet.