Rapid and sensitive electrochemical sensor of cross-linked polyaniline/oxidized carbon nanomaterials core-shell nanocomposites for determination of 2,4-dichlorophenol.

Nanocomposites (NCs) of crosslinked polyaniline (CPA)-coated oxidized carbon nanomaterials (OXCNMs) were fabricated as a very sensitive and simple electrochemical sensor to be utilized in 2,4-dichlorophenol (2,4-DCPH) detection. CPA/OXCNMs NCs were prepared by chemical copolymerization of polyaniline with triphenylamine and p-phenylenediamine in the presence of OXCNMs. The CPA/GO-OXSWCNTNCs exhibited a higher affinity for the oxidation of chlorophenols compared to the glassy carbon electrode (GCE), CPA/GCE, and other NCs. Cyclic voltammetry was performed to investigate and assess the electrocatalytic oxidation of 2,4-DCPH on the modified GCE. The compound yielded a well-defined voltammetric response in a Britton-Robinson buffer (pH 5) at 0.54 V (vs. silver chloride electrode). Quantitative determination of 2,4-DCPH was performed by differential pulse voltammetry under optimal conditions in the concentration range of 0.05 to 1.2 nmol L-1, and a linear calibration graph was obtained. The detection limit (S/N = 3) was found to be 4.2 nmol L-1. In addition, the results demonstrated that the CPA/GO-OXSWCNTs/GCE sensor exhibited a strong anti-interference ability, reproducibility, and stability. The prepared CPA/GO-OXSWCNTs/GCE sensor was used to rapidly detect 2,4-DCPH with a high degree of sensitivity in fish farm water with proven levels of satisfactory recoveries.

An Ultrasensitive Detection Platform for Mercury Ions Speciation in Water Using Procaine Hydrochloride Ion Pair Coupled Extractive Spectrofluorimetry.

A simple extractive spectrofluorimetric strategy for trace determination of mercury(II) ions in water employing procaine hydrochloride (PQ+) as an ion pairing fluorescent tagging reagent has been established. The method was based upon the extraction of PQ+ from aqueous iodide media onto dichloromethane as a ternary complex ion associate [(PQ+)2.(HgI4)2-] at pH 9.0-10.0 with subsequent quenching at λex/em = 268/333 nm. The developed strategy exhibited a linear range 20-140 nM with a lower limit of detection (LOD) 6.1 nM, respectively. Intra and inter-day laboratory accuracy and precision for trace analysis of mercury(II) ions in water were performed. Complexed mercury(II) species in real water samples were evaluated along with chemical speciation and successful comparison with most of the reported methods. The method was validated by standard inductively coupled plasma-optical emission spectrometry (ICP-OES) method in terms of student's t- and F tests at 95% confidence interval. The method offers rapidity, selectivity, cost-effectiveness, robustness, and ruggedness. Graphical Abstract Schematic illustration of the proposed sensing mechanism for mercury(II).