Selective Determination Of Mercury Ions Research Articles

The fabrication of a hybrid fluorescent nanosensing system and its practical applications via film kits for the selective determination of mercury ions

Heavy metal ions especially mercury exposure have severe toxic effects on living organisms and human health. Therefore, easy, accessible, and accurate determination strategies for the selective specification of mercury ions are essential for numerous disciplines. In the presented paper, new hybrid fluorescent iron oxide nanoparticles labeled with carbazole and triazole units (CT-IONP) were prepared via surface modification for the spectrofluorimetric determination of Hg2+ in environmental samples. The structure of the new sensing system is characterized via various spectroscopic, thermal, and microscopic techniques. Under optimized conditions, the hybrid system is not only used in fully water media but also highly fluorescent which led to the “turn-off” response towards Hg2+ ion in the presence of various competitive species. The presented sensing system was successfully used for the determination of Hg2+ ions in the wide linear working range (0.02–10.00 µmol.L−1) at nanomolar levels, where the limit of detection and quantification were calculated as 7.38 and 22.14 nmol.L−1. Importantly, the practical application of hybrid material was applied by CT-IONP embedded polycaprolactone (PCL) polymer film kits. The bluish color of fabricated film kits was instantly and dramatically turned colorless-dark patterns after the addition of Hg2+ ions, which resulted in convenient and rapid film test kits for selective detection.

Highly fluorescent hydroxyl groups functionalized graphitic carbon nitride for ultrasensitive and selective determination of mercury ions in water and fish samples

Heavy metal ion pollution is always a serious problem worldwide. Therefore, monitoring heavy metal ions in environmental water is a crucial and difficult step to ensure the safety of people and the environment. A mercury ion (Hg2+) fluorescence probe with excellent sensitivity and selectivity is described here. The functionalized graphitic carbon nitride nanosheets (T/G-C3N4) fluorescence probe was fabricated using melamine as a precursor by the pyrolysis technique, followed by a rapid KOH heat treatment method for 2 min. The chemical structure and morphology of the T/G-C3N4 probe were characterized using multiple analytical techniques including UV–Vis, SEM, XPS, XRD, and fluorometer spectroscopy. Geometry optimization of T/G-C3N4 as a modified probe was performed to assess its stability and interaction ability with Hg(II) via using the density function approach. The T/G-C3N4 probe showed a linear response based on quenching over the range 0–1.25 × 103 nM Hg(II); the detection limit was 27 nM. The remarkable sensitivity of T/G-C3N4 towards the Hg2+ ions was explained by the intense coordination and fast chelation kinetics of Hg2+ with the NH2, CN, C=N, and OH groups of T/G-C3N4 nanoprobe. The T/G-C3N4 probe demonstrates exceptional selectivity for Hg2+ ions among other metal ions including (Na+, Ag+, Mg2+, Fe2+, Fe3+, Co2+, Ni2+, Cd2+, K+, Ca2+, Cu2+, Pb2+, Mn2+ and Hg2+) and over a broad pH range (6–10), together with remarkable long-term fluorescence stability in water (> 30 days) and minimal toxicity. T/G-C3N4 was used to detect and quantify Hg2+ ions in tuna and mackerel fish and the results compared to ICP-AES. The results obtained offer a new simple and green technique for the design of multifunctional fluorescent probe appropriate for environmental applications.Graphical

A LATERAL FLOW TEST SYSTEM FOR THE SENSITIVE DETERMINATION OF MERCURY IONS IN WATER BODIES

A lateral flow test system has been implemented and the conditions for the sensitive and selective determination of mercury ions in the matrix of natural waters have been optimized. A linear range for mercury ions concentration from 0.3 to 25 ng/ml and limit of detection of 0.13 ng/mL were achieved, which meets the practical requirements for drinking water.

Construction of an effective ratiometric fluorescent sensing platform for specific and visual detection of mercury ions based on target-triggered the inhibition on inner filter effect.

Sensitive and selective determination of mercury ion (Hg2+) is critical for human health and environmental monitoring. Herein we construct an effective ratiometric fluorescent sensing platform by combining green fluorescent polymer carbon dots (PCDs) and red fluorescent tetraphenylporphyrin tetrasulfonic acid hydrate (TPPS) for specific and visual detection of Hg2+. The fluorescence of PCDs can be quenched by TPPS through inner filter effect (IEF). In the presence of both Mn2+ and Hg2+, however, Hg2+ can expedite the complexation of TPPS and Mn2+, which causes the decrease in both fluorescence and absorption of TPPS, accompanied by the fluorescence recovery of PCDs due to the subdued IFE between TPPS and PCDs. Based on the change of fluorescence signal, a ratiometric fluorescent sensing platform is constructed for specific and visual detection of Hg2+. The proposed approach presents a fine linear range for Hg2+ over the range of 10-200 nM with a detection limit of 0.038 nM. Moreover, an easily distinguishable fluorescence color change from pink to green with the increase of Hg2+ concentration can be observed by the naked eye under a UV lamp. Such a simple and effective method shows great potential for visual sensing of Hg2+ in on-site and resource-limited settings.

ZnO decorated with organic nanoparticles based sensor for the ratiometric selective determination of mercury ions

Fully characterized organic nanoparticles (R1) decorated on the surface of ZnO (N1), used for selective nanomolar determination of mercury ions.

A novel electrochemical biosensor for selective determination of mercury ions based on DNA hybridization

An electrochemical biosensor was developed for Hg2+ determination based on DNA hybridization. In the presence of Hg2+, the target and probe DNAs with thymine–thymine (T–T) mismatches could hybridize by forming T–Hg2+–T complex. This induced DNA hybridization led to the decrease in reduction peak currents of ethyl green (EG) as electroactive label, which could be used for determination of Hg2+. The difference in the value of the peak currents of EG before and after DNA hybridization (ΔI) was linear with the concentration of Hg2+ in the range of 9.0 × 10−11–1.0 × 10−9 M. The detection limit was 3.08 × 10−11 M.

Influence of Alkyl Chain on a Neutral-Carrier for Use in Selective Membranes Mercury Ions

Regarding the ISEs, their recognition element or ionophore is the main parameter to be considered at their building time, which is the reason to synthesize four molecules of the same family, all of them candidates to be the best recognition element for building a novel Hg(II) ions selective electrode with a solid inner contact. The difference between the four structures is the alkyl group bound to one of the sulphur donating groups, the aliphatic chain can be: methyl, ethyl, propyl or butyl. Electrodes were prepared for each of the ionophores synthesized using the composition (%) of the ionophore membrane: o-NPOE:PVC:NaTPB with 5:62:33:1.0mg. The best neutral-carrier for the selective determination of mercury ions proves to be the ionophore containing the methyl in its structure, as its detection limit of (9.1 ± 0.8)x10−10 mol L-1, linear range (1.0x10−9 a 1.0x10−1) mol L-1 and Nernstian response (29.8 ± 0.4) mV decade-1 demonstrated.

Influence of Alkyl Chain on a Neutral-Carrier for Use in Selective Membranes Mercury Ions

The recognition element or ionophore of the ISEs, is the main constituent to be considered during their building, which is the reason to synthesize four molecules of the same family, all of them candidates to be the best recognition element for building a novel Hg(II) ions selective electrode with a solid inner contact. The difference between the four structures is the alkyl group bound to one of the sulphur donating groups, the aliphatic chain can be: methyl, ethyl, propyl or butyl. The electrodes were prepared for each of the ionophores synthesized using the composition of the ionophore membrane: o-NPOE:PVC:NaTPB with 5:62:33:1.0mg (%, w/w). The best neutral-carrier for the selective determination of mercury ions proved to be the ionophore containing the methyl in its structure, as demonstrated by its detection limit (9.1 ± 0.8) x 10−10 mol L- 1, linear range (1.0 x 10−9 to 1.0 x 10−1) mol L- 1 and a Nernstian response (29.8 ± 0.4) mV decade-1.

A New Triazene Ligand Immobilized on Triacetylcellulose Membrane for Selective Determination of Mercury Ion

A new simple and inexpensive optical chemical sensor for mercury(II) ion in aqueous solutions is presented. The mercury sensing membrane was prepared by incorporating of triazene ((E)-1-(2-ethoxyphenyl)-3-(4-nitrophenyl) triaze-1-ene) (L) as a suitable ligand for Hg(II) on triacetylcellulose membrane. Spectrophotometric study of complex formation between the triazene ligand L and Hg2+ in dimethyl formamide solution indicated a large stability constant for the mercury ion complex. The membrane responds to mercury ion by changing color reversibly from orange to green in buffer solution at pH 3.0. A linear relationship was observed between the membrane absorbance at 405 nm in a range from 7 to 90 µg mL-1 with a limit of detection of 64 ng mL-1 in aqueous solutions at pH 3.0. The optical sensor was successfully applied to the determination of mercury in spiked water samples.

DNA pseudoknot-functionalized sensing platform for chemoselective analysis of mercury ions

A novel, simple, signal-enhanced electrochemical sensor was designed for sensitive and selective determination of mercury ions by using target-triggered conformational change of DNA pseudoknots with the assistance of auxiliary DNA strands.

Selective Determination of Mercury Ion in River Water by Solvent Extraction with 4,6‐Dimethyl‐2‐Mercaptopyrimidine Followed by Reversed‐Phase HPLC

A selective determination method for mercury (Hg) ion in river water has been developed by solvent extraction, followed by reversed‐phase HPLC with photometric detection. The Hg(II) ion was quantitatively extracted into chloroform over the pH range of 2.9 to 5.4 as 4,6‐dimethyl‐2‐mercaptopyrimidine (DMMP) chelate. Job's method indicated that the Hg‐DMMP chelate composition was Hg(DMMP)2. The extracted Hg‐DMMP chelate was then separated on an ODS column with an eluent of methanol/water/0.1 M DMMP (60∶40∶0.25, v/v) and detected at 255 nm. The correlation coefficients of the calibration curves obtained with 5 mL Hg standards were more than 0.999 over the range of 0.2 µg/mL (ppm) to 10 ppm. The detection limit of the Hg ion in 5 mL water was estimated as 0.02 ppm, by a signal to noise ratio of 3. The recoveries with a spiked river water sample for 0.5 and 5 ppm Hg ion (N=5) were 100.9±1.2% and 100.1±0.8%, respectively. Effects of foreign ions on the determination of 0.5 ppm Hg ion were investigated with 57 metal ions. Almost none of the ions interfered except for Ag(I), Au(III), and Cu(II).

Calixarene capped quantum dots as luminescent probes for Hg 2+ ions

Luminescent and stable CdSe/ZnS core/shell quantum dots (QDs) capped with sulfur calixarene are prepared for the selective determination of mercury ions in acetonitrile with high sensitivity.