Design and Characterization of Electrochemical Sensor for the Determination of Mercury(II) Ion in Real Samples Based upon a New Schiff Base Derivative as an Ionophore

Abstract

The present paper provides a description of the design, characterization, and use of a Hg2+ selective electrode (Hg2+–SE) for the determination of Hg2+ at ultra-traces levels in a variety of real samples. The ionophore in the proposed electrode is a new Schiff base, namely 4-bromo-2-[(4-methoxyphenylimino)methyl]phenol (BMPMP). All factors affecting electrode response including polymeric membrane composition, concentration of internal solution, pH sample solution, and response time were optimized. The optimum response of our electrode was obtained with the following polymeric membrane composition (% w/w): PVC, 32; o-NPOE, 64.5; BMPMP, 2 and NaTPB, 1.5. The potentiometric response of Hg2+–SE towards Hg2+ ion was linear in the wide range of concentrations (9.33 × 10–8−3.98 × 10–3 molL–1), while, the limit of detection of the proposed electrode was 3.98 × 10–8 molL–1 (8.00 μg L–1). The Hg2+–SE responds quickly to Hg2+ ions as the response time of less than 10 s. On the other hand, the slope value obtained for the developed electrode was 29.74 ± 0.1 mV/decade in the pH range of 2.0−9.0 in good agreement with the Nernstian response (29.50 mV/decade). The Hg2+–SE has relatively less interference with other metal ions. The Hg2+–SE was used as an indicator electrode in potentiometric titrations to estimate Hg2+ ions in waters, compact fluorescent lamp, and dental amalgam alloy and the accuracy of the developed electrode was compared with ICP–OES measurement values. Moreover, the new Schiff base (BMPMP) was synthesized and characterized using ATR–FTIR, elemental analysis, 1H NMR, and 13C NMR. The PVC membranes containing BMPMP as an ionophore unloaded and loaded with Hg(II) are reported by scanning electron microscope images (SEM) along with energy-dispersive X-ray spectroscopy (EDX) spectra.

Rapid electrochemical sensor for uranium(vi) assessment in aqueous media

“…This could be possibly attributed to the leaching of membrane ingredients into the sample solution during use. 42 Additionally, the membrane swelling led to a fragile sensor close to its lifespan termination.…”

Materials Approaches for Improving Electrochemical Sensor Performance

“…Schiff bases include a collection of imines, or compounds with the general structure R 1 R 2 C = NR′ (R′ ≠ H), and they are utilized as ionophores for metal coordination . A very recent study developed a sensor for aqueous mercury ion (Hg 2+ ) detection by synthesizing a 4-bromo-2-[(4-methoxyphenylimino)­methyl]­phenol (BMPMP) Schiff base to modify an ion-selective electrode . The resulting sensor benefitted from the selectivity of the Schiff base, coordinating with mercury­(II) ions over interfering metal ions and demonstrated an impressive detection range from 93.30 nM to 3.98 mM .…”

“…71 A very recent study developed a sensor for aqueous mercury ion (Hg 2+ ) detection by synthesizing a 4-bromo-2-[(4methoxyphenylimino)methyl]phenol (BMPMP) Schiff base to modify an ion-selective electrode. 72 The resulting sensor benefitted from the selectivity of the Schiff base, coordinating with mercury(II) ions over interfering metal ions and demonstrated an impressive detection range from 93.30 nM to 3.98 mM. 72 Another study marked the first use of a dextrincysteine Schiff base (DCS) for electrochemical and fluorescent detection of mercury(II), exhibiting an electrochemical limit of detection of less than 1 nM.…”

“…72 The resulting sensor benefitted from the selectivity of the Schiff base, coordinating with mercury(II) ions over interfering metal ions and demonstrated an impressive detection range from 93.30 nM to 3.98 mM. 72 Another study marked the first use of a dextrincysteine Schiff base (DCS) for electrochemical and fluorescent detection of mercury(II), exhibiting an electrochemical limit of detection of less than 1 nM. 73 Capable of detecting more than just ions, sometimes Schiff bases are used to fabricate metal complexes on electrodes, such as nickel 71 or cobalt 74 Schiff base complexes, in order to sense molecular analytes.…”

Dual-Emission Fluorescence Probe Based on CdTe Quantum Dots and Rhodamine B for Visual Detection of Mercury and Its Logic Gate Behavior

“…Up to now, many techniques have been developed to determine mercury ions, including inductively coupled plasma mass spectrometry, atomic absorption spectrometry, anodic stripping voltammetry and electrochemical methods, etc. [ 5 , 6 , 7 , 8 ]. These analytical techniques can measure the levels of mercury sensitively and accurately, but they have to be operated using expensive and sophisticated equipment and require complicated sample preparation procedures, which limits their application for rapid and simple detection [ 9 ].…”