Fabrication of Novel and Potential Selective 4-Cyanophenol Chemical Sensor Probe Based on Cu-Doped Gd2O3 Nanofiber Materials Modified PEDOT:PSS Polymer Mixtures with Au/µ-Chip for Effective Monitoring of Environmental Contaminants from Various Water Samples

Herein, a novel copper-doped gadolinium oxide (Cu-doped Gd2O3; CGO) nanofiber was synthesized by a simple solution method in the basic phase and successfully characterized. We have used Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Energy-Dispersive Spectroscopy (EDS) techniques for characterization of the CGO nanofiber. The CGO nanofiber was used later to modify Au-coated μ-Chips with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) polymer mixtures (coating binder) to selectively detect 4-cyanophenol (4-CP) in an aqueous medium. Notable sensing performance was achieved with excellent sensitivity (2.4214 µAµM−1 cm−2), fast response time (~12 s), wide linear dynamic range (LDR = 1.0 nM–1.0 mM: R2 = 0.9992), ultra-low detection limit (LoD; 1.3 ± 0.1 pM at S/N = 3), limit of quantification (LoQ; 4.33 pM), and excellent reproducibility and repeatability for CGO/Au/μ-Chip sensor. This CGO modified Au/μ-chip was further applied with appropriate quantification and determination results in real environmental sample analyses.

First Report for Determination of d-Penicillamine in the Presence of Tryptophan Using a 2-Chlorobenzoyl Ferrocene/Ag-Supported ZnO Nanoplate–Modified Carbon Paste Electrode

In this work, a carbon paste electrode modified with Ag-ZnO nanoplates and 2-chlorobenzoyl ferrocene was prepared and applied for the determination of d-penicillamine in the presence of tryptophan. The morphologies of Ag-ZnO nanoplates were examined by scanning electron microscopy. It was found that under an optimum condition (pH 7.0), the oxidation of d-penicillamine at the surface of such an electrode occurs at a potential about 165 mV less positive than that of an unmodified carbon paste electrode. The diffusion coefficient (D = 7.6 × 10−6 cm2/s) and the electron transfer coefficient (α = 0.54) for d-penicillamine oxidation were also determined. The proposed method exhibited a wide linear dynamic range of 0.03–250.0 µM, with an LOD (S/N = 3) of 0.015 µM. Moreover, the modified electrode exhibited good reproducibility and high selectivity, demonstrating its feasibility for the analytical purpose. Lastly, this new sensor was used for the determination of d-penicillamine and tryptophan in real samples.

Construction of Eu3+Ion-Selective Electrode Based on 1,2-Diaminopropane-N,N,N',N'-tetraacetic acid

A new Eu3+PVC membrane electrode based on 1,2-diaminopropane-N, N,N',N'-tetraacetic acid (DAPTA) as a suitable ionophore has been prepared and studied. The electrode shows a good selectivity for Eu(III) ion with respect to most common cations including alkali, alkaline earth, transition and heavy metal ions. This electrode has a wide linear dynamic range from 1.0×10-6to 1.0×10-2M with a Nernstian slope of 19.7±0.5 mV per decade and a low detection limit of 7.2×10-7M in the pH range of 2.5–9.1, while the response time was rapid (<10 s). The practical utility of the electrodes has been demonstratedby their use as indicator electrodes in the potentiometric titration of Eu3+ions with EDTA and for the determination of Eu3+in some water sample solutions.

Dispersive liquid-liquid microextraction and liquid chromatographic determination of pentachlorophenol in water

A simple and sensitive dispersive liquid-liquid microextraction method for extraction and preconcentration of pentachlorophenol (PCP) in water samples is presented. After adjusting the sample pH to 3, extraction was performed in the presence of 1% W/V sodium chloride by injecting 1 mL acetone as disperser solvent containing 15 μL tetrachloroethylene as extraction solvent. The proposed DLLME method was followed by HPLC-DAD for determination of PCP. It has good linearity (0.994) with wide linear dynamic range (0.1–1000 μg L−1) and low detection limit (0.03 μg L−1), which makes it suitable for determination of PCP in water samples.