Ions In Food Samples Research Articles

Electrochemical sensors for sensitive and selective detection of nitrite based on flexible gold microneedle like nanodendrites modified electrode

In this study, we present a new approach utilizing Au nanodendrites (Au NDs) to modify flexible screen-printed carbon electrodes (FSPCEs), offering an efficient platform for voltammetric sensing of nitrite ions in food samples. The FSPCEs are created with gold leaf-like nanodendrites through a simple, one-step electrochemical deposition process. The direct growth of these Au NDs occurs efficiently on the carbon-paste electrode, eliminating the need for binders or additional reducing agents and organic solvents, owing to the aforementioned matrix. The modified electrodes serve as promising sensing platforms for nitrite detection. The outcomes demonstrated that a significant amount of AuNPs with dendritic morphologies were dispersed throughout the FSPCE.These novel flexible electrodes act as effective electrocatalyst for NO2− oxidation due to their large electrochemical active surface area (ECSA), well-dispersed Au nanostructures, and high electrical conductivity. The optimized sensor exhibits a wide linear response range from 0.02 to 5.8 µM, with 1.0 nM limit of detection, an impressive sensitivity of 52.529 µA µM−1 cm−2 and a quick current response time (< 3 s) towards nitrite ions. Additionally, the suggested sensor demonstrates high selectivity, reproducibility, and stability. Furthermore, the FSPCEs are evaluated for their ability to selectively detect nitrite ions in various food samples such as tap water, drinking water, milk, and fruit juices, comparing the results with standard methods in real sample analysis. The fabricated sensors show promising potential for practical applications in food and environmental analysis. Consequently, Au NDs@FSPCE electrode emerged to be a novel platform for NO2− electrochemical detection. Because of their great affinity for analytical substances in solutions, gold nanodendrites supported on flexible screen-printed carbon electrodes (FSPCEs) are very useful for electrode modifications. Their increased effective surface area, which greatly raises the electrode's sensitivity and specificity for a range of analytical applications, is responsible for their high affinity.

Nitrogen-doped carbon quantum dots (NCQDs) detected to mercury ions in food monitoring

Using 2,3-diaminopyridine and citric acid as precursors, blue fluorescent nitrogen-doped carbon quantum dots (NCQDs) with a narrow size distribution (∼7.2 nm) were prepared and applied in the following assay for mercury ion detection at a weight ratio of 2,3-diaminopyridine:citric acid = 1:1 (0.2 g: 0.2 g, 20 mL for H2O), 220 °C, and 10 h. NCQDs was characterized by TEM, FT-IR, XPS, UV–Vis and EDS, and the prepared NCQDs display excitation-independent behavior due to less surface defects and uniform size. The optimal excitation and emission wavelengths of the NCQDs were 380 nm and 430 nm, respectively. Interestingly, the fluorescence of the NCQDs could be rapidly and selectively quenched by Hg2+ within 9 min at room temperature without further modification. Under optimal conditions, the limit of detection (LOD) was measured to be at the nanomolar level (42.4 nmol/L) with a linear range of 0–5.0 μmol/L, and fluorescence analysis of NCQDs was successfully used for the qualitative and quantitative analysis of mercury ions in food samples. Furthermore, our results revealed that fluorescence quenching occurred under the common fluences of the inner filter effect, and the static quenching effect was authenticated in the process in which Hg2+ coordinates with the NCQDs to form nonfluorescent complexes.

Research progress in the detection of trace heavy metal ions in food samples.

Food safety is the basis for ensuring human survival and development. The threat of heavy metal ions to food safety has become a social concern with the rapid growth of the economy and the accompanying environmental pollution. Some heavy metal ions are highly toxic even at trace levels and pose significant health risks to humans. Therefore, ultrasensitive detection of heavy metal ions in food samples is important. In this mini-review, recent advances in the analytical methods based on nanomaterials for detecting trace heavy metal ions in food samples are summarized in three categories: electrochemical, colorimetric, and fluorescent methods. We present the features and sensing mechanisms of these three methods, along with typical examples to illustrate their application in the detection of heavy metal ions in foods. This mini-review ends with a discussion of current challenges and future prospects of these approaches for sensing heavy metal ions. The review will help readers understand the principles of these methods, thereby promoting the development of new analytical methods for the detection of heavy metal ions in food samples.

Simultaneous electrochemical sensing of heavy metal ions (Zn2+, Cd2+, Pb2+, and Hg2+) in food samples using a covalent organic framework/carbon black modified glassy carbon electrode

In this study, for the first time, a selective electrochemical sensor by glassy carbon electrode (GCE) modified with the covalent organic framework (COF) and carbon black (CB) was introduced and applied to simultaneous sensing of Zn2+, Cd2+, Pb2+, and Hg2+ via differential pulse anodic stripping voltammetry (DPASV). The COF is supplied through a condensation reaction between melamine and trimesic acid. The COF and CB, which are used to modify the GCE surface, increase electrochemical activity. The linearity to determine ions was achieved as Zn2+: 0.009–1100 nM, Cd2+: 0.005–1100 nM, Pb2+: 0.003–1100 nM, and Hg2+: 0.001–1100 nM. Besides, the detection limits for Zn2+, Cd2+, Pb2+, and Hg2+ have obtained 0.003, 0.002, 0.001 and 0.0003 nM, respectively. The CB-COF/GCE was applied to simultaneously measure the ions in food samples. For validation, atomic absorption spectrometry (AAS) was applied to measure the amount of target metal ions as a standard method in real samples.

Ultra-sensitive electrochemical sensors through self-assembled MOF composites for the simultaneous detection of multiple heavy metal ions in food samples

Using an assemble-able MOF material, we successfully constructed an ultra-sensitive electrochemical sensor based on Bi2CuO4@Al-MOF@UiO-67 nanocomposite material, in order to investigate the adsorption properties of the Bi2CuO4@Al-MOF@UiO-67 functional material on the heavy metal ion. The Cd2+, Cu2+, Pb2+ and Hg2+ can be detected at the same time. Selective recognition and enrichment of various metal ions on different substrates can be achieved through the assembly of a large number of Al-MOF and UiO-67-MOF nanomaterial composites with small particle sizes on the Bi2CuO4 surface. Based on this, a new type of sensor is researched and prepared, which has been shown to have good stability and reproducibility. Due to its unique assembly structure, large active surface area, excellent adsorption capacity, and high electrical conductivity, Bi2CuO4@Al-MOF@UiO-67 presents outstanding performance. In addition, the sensor also exhibits excellent electrocatalytic redox capacity and high selectivity. The adsorption capacity of Cd2+, Cu2+, Pb2+ and Hg2+ is also significantly improved under the action of the sensor electrode, however, this is not the case. The limits of detection for Cd2+, Cu2+, Pb2+ and Hg2+ were found to be 0.02 pM, 0.032 pM, 0.018 pM and 0.041 pM, respectively. In order to investigate the detection mechanism of Cd2+, Cu2+, Pb2+ and Hg2+ was adsorption properties as well as electrochemical accumulation of Bi2CuO4@Al-MOF@UiO-67 on the metal atoms were investigated. This method has been successfully applied to samples of rice, sorghum, maize, milk, honey, and tea, and has enabled the simultaneous detection of Cd2+, Cu2+, Pb2+ and Hg2+, which is of significant practical value.

A novel AIE peptide-based fluorescent probe for highly selective detection of mercury(II) ions and its application in food samples and cell imaging

A novel peptide-based fluorescent probe TPE-PGH was firstly developed based on aggregation-induced emission (AIE) effect. The fluorescence intensity of TPE-PGH was largely ignored in the low water fraction, whereas bright blue fluorescence was observed in the high water fraction. TPE-PGH achieved high selectivity and rapid detection of Hg2+, and has excellent sensitivity to detect Hg2+ with low LOD (58.1 nM). Interestingly, TPE-PGH provided a significant color changed from dark blue to bright cyan upon binding with Hg2+ ions under UV lamp (365 nm). In addition, TPE-PGH was able to simultaneously visualize Hg2+ in living cells with different fluorescence intensities based on excellent cells permeability and low toxicity. Further, TPE-PGH exhibited high precision (RSD < 4 %), and was successfully applied for detecting Hg2+ in real food samples, such as milk, soda drink, red wine, cucumber, tomato and carrot. Successful test strips responses also demonstrated that the potential of TPE-PGH for portable detection of Hg2+ in real samples. Especially, AIE based-test strips soaked in different Hg2+ concentrations was successfully utilized for semi-quantitative detection of Hg2+ using the RGB APP installed on a smartphone, which will provide a new approach for smart and portable detection of contaminated heavy metal ions in food samples.

An ultrasensitive electrochemical sensor based on antimonene simultaneously detect multiple heavy metal ions in food samples.

Here, we constructed a novel ultra-sensitive electrochemical sensor based on ZIF-67@antimonene (AMNFs) nanocomposites which are based on the first-principles density functional theory the adsorption properties of antimonene on heavy metal ions were studied for simultaneous determination of Cu2+, Pb2+ and Hg2+. The ZIF-67@AMNFs was prepared by using ZIF-67 MOF surface loaded with a large amount of antimonene sheet. Its morphology and crystal structure were characterized by Transmission electron microscope (TEM), Energy Dispersive Spectroscopy (EDS), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). Functional ZIF-67@AMNFs due to its unique layered structure, large active surface area, strong adsorption capacity and good electrical conductivity. In addition, the adsorption capacity of the sensor electrode for Cu2+, Pb2+ and Hg2+ was effectively enhanced. The detection limits of Cu2+, Pb2+ and Hg2+ were 0.01pM, 0.042pM and 0.031pM, respectively. The determination mechanism of Cu2+, Pb2+ and Hg2+ was further clarified based on the adsorption properties and electrochemical accumulation of antimonene on metal atoms. It has been successfully applied to the simultaneous determination of Cu2+, Pb2+ and Hg2+ in rice, sorghum, corn, milk, honey and tea samples, and has good practicability.

AIE active luminous dye with a triphenylamine attached benzothiazole core as a portable polymer film for sensitively detecting CN- ions in food samples

Aggregation-induced emission (AIE) active 3-(3-(benzo[d]thiazol-2-yl)-2-hydroxyphenyl)-2-(4'-(diphenylamino)-[1,1′-biphenyl]-4-yl)acrylonitrile (BTPA) has been designed and synthesized herein, with the goal of detecting CN− ions at a low-level in semi–aqueous medium. The deliberate addition of the electron-deficient alkene BTPA increased its sensitivity and selectivity to CN− ions, with a better detection limit of 6.4 nM, unveiling the next-generation approach to creating sophisticated CN− ions selective chemosensors. The ESI-MS and NMR spectra analyses provided strong support for the structures of the chemosensors, while the UV–Vis, photoluminescence, and 1H-NMR titration experiments provided support for the sensing efficiencies. Subsequently, PVDF/BTPA electrospun nanofibers have been effectively produced as functional films. These nanofiber films exhibit outstanding mechanical strength, photo/thermal stability, and optical responsiveness to CN− ions, making them a potential choice for on-field emerging contaminant detection.

Dispersive Micro-Solid Phase Extraction Using a Graphene Oxide Nanosheet with Neocuproine and Batocuproine for the Preconcentration of Traces of Metal Ions in Food Samples.

A dispersive micro-solid phase extraction (Dµ-SPE) method for the preconcentration of trace metal ions (Pb, Cd, Cr, Mn, Fe, Co, Ni, Cu, Zn) on graphene oxide with the complexing reagents neocuproine or batocuproine is presented here. Metal ions form cationic complexes with neocuproine and batocuproine. These compounds are adsorbed on the GO surface via electrostatic interactions. The factors affecting the separation and preconcentration of analytes such as pH, eluent (concentration, type, volume), amount of neocuproine, batocuproine and GO, mixing time, and sample volume were optimized. The optimal sorption pH was 8. The adsorbed ions were effectively eluted with 5 mL 0.5 mol L-1 HNO3 solution and determined by the ICP-OES technique. The preconcentration factor for the GO/neocuproine and GO/batocuproine in the range 10-100 and 40-200 was obtained for the analytes, with detection limits of 0.035-0.84 ng mL-1 and 0.047-0.54 ng mL-1, respectively. The method was validated by the analysis of the three certified reference materials: M-3 HerTis, M-4 CormTis, and M-5 CodTis. The procedure was applied to determine metal levels in food samples.

Simultaneous electrochemical determination of Pb2+ and Cd2+ ions in food samples by a silver nanoparticle/COF composite modified glassy carbon electrode

Simultaneous electrochemical determination of Pb2+ and Cd2+ ions in food samples by a silver nanoparticle/COF composite modified glassy carbon electrode

A novel modified magnetic Co-MOF-71 for magnetic solid phase extraction of Hg(II) ions in food samples

A novel modified magnetic Co-MOF-71 for magnetic solid phase extraction of Hg(II) ions in food samples

Rapid detection of I− in food samples by cholesteric chiral artificial receptor L5

In this study, a cholesteric chiral artificial receptor L5 was synthesized and a rapid method for the detection of iodide ions was established. The addition of L5 to Ethanol/Tris (V/V = 1/1, pH 7.0) solution changed the iodide ion solution from colorless to light yellow to achieve the naked-eye identification. The identification pattern was confirmed with the help of spectral titration, job test and anti-interference test, and it was found that L5 bound to iodide ion in a 1:1 coordination ratio. It was also confirmed that the hydrogen atoms of the amide group of MeO-PhCONH in L5 and the hydrogen atoms of –COOCH3 in L5 interacted with I− through hydrogen bonding force by 1H NMR titration, infrared spectroscopy, scanning electron microscopy and computer molecular simulation. The detection limit of L5 was 0.025 µmol/L, which could efficiently and conveniently detect iodide ions in food samples.

Functionalization of biogenic silver nanoparticles with Vitamin B12 for the detection of iron in food samples

A comprehensible, validated, and simple method was developed for the determination of Fe+3 ions in food samples. To accomplish this, Vitamin B12-functionalized biological silver nanoparticles (FAgNPs) were synthesised and employed. The test of sensitivity showed 2 mgL−1 as the limit of detection for Fe+3 ions by FAgNPs. The intra-day and inter-day recoveries of Fe+3 were observed in the range of 78–88% and 74–94%, respectively. Moreover, the procedure was successfully applied for Fe+3 ion detection in some cereals and commercially available baby food products. The application of FAgNPs-based methods showed high specificity and sensitivity, providing a promising strategy to detect low Fe+3 ion concentration in the range of 2–10 mgL−1. When compared to atomic absorption spectrophotometry, the detection efficiency of FAgNPs-based method was comparable and acceptable. The proposed methodology is a low-cost and portable nanoparticle-based technology for rapid assessment of Fe+3 ions with promising potential for practical implementation, beside being sustainable due to its biogenic nature.

"Switch-Off-On" Detection of Fe3+ and F- Ions Based on Fluorescence Silicon Nanoparticles and Their Application to Food Samples.

An approach to the detection of F− ions in food samples was developed based on a “switch-off-on” fluorescence probe of silicon nanoparticles (SiNPs). The fluorescence of the synthetic SiNPs was gradually quenched in the presence of Fe3+ ion and slightly recovered with the addition of F− ion owing to the formation of a stable and colorless ferric fluoride. The fluorescence recovery exhibited a good linear relationship (R2 = 0.9992) as the concentration of F− ion increased from 0 to 100 μmol·L−1. The detection limit of the established method of F− ion was 0.05 μmol·L−1. The recovery experiments confirmed the accuracy and reliability of the proposed method. The ultraviolet–visible spectra, fluorescence decays, and zeta potentials evidenced the fluorescence quenching mechanism involving the electron transfer between the SiNPs and Fe3+ ion, while the fluorescence recovery resulted from the formation of ferric fluoride. Finally, SiNPs were successfully applied to detect F− ions in tap water, Antarctic krill, and Antarctic krill powder.

Dual fluorometric biosensor based on a nanoceria encapsulated metal organic framework and a signal amplification strategy of a hybridization chain reaction for the detection of melamine and Pb2+ ions in food samples

The increased need for melamine and Pb2+ ion detection systems that are versatile, ultra-sensitive, and easy to use is highly significant.

Human peripheral blood mononuclear cells targeted multidimensional switch for selective detection of HSO3− anion

A new ratiometric π-conjugated luminophore with donor-acceptor (D- π- A) network CM {(E)-2-(4-(2-(9-butyl-9H-carbazol-3-yl)vinyl)benzylidine)malononitrile} has been synthesized by malononitrile conjugated carbazole dye with an intervening p-styryl spacer. Here, p-styryl conjugated malononitrile is used as a recognition site for the detection of HSO3− with a fast response time (within 50 s). In a mixed aqueous solution, CM reacts with HSO3− to give a new product 1-(9-butyl-9H-carbazol-3-yl)-2-(4-(2, 2-dicyanovinyl)phenyl)ethane-1-sulfonic acid. The probe exhibits positive solvatofluorochromism with solid state red fluorescence. The restriction of intermolecular rotation of p-styryl conjugated malononitrile unit enhances the typical solid state fluorescence properties. The probe (CM and its corresponding aldehyde CA) also demonstrates a strong solvent dependence yielding blue to green to pink and even red fluorescence in commonly used organic solvents like n-hexane, toluene, diethyl ether (DEE), THF, DCM, Dioxane, CH3CN and MeOH. The chemodosimetric approach of HSO3− selectively takes place at the olefinic carbon exhibiting a prominent chromogenic as well as ratiometric fluorescence change with a 147 nm blue-shift in the fluorescence spectrum. CM can detect HSO3− as low as 1.21 × 10−8 M. Moreover, the CM can be successfully applied to detect intrinsically generated intracellular HSO3− in human peripheral blood mononuclear cells (PBMCs). CM has shown sharp intensities (2628 ± 511.8) when the cells are HSO3− untreated. At green channel (at 486 nm) almost negligible fluorescence intensities are found (423 ± 127.5) for HSO3− untreated samples. However, the green fluorescence (2863 ± 427.5) increases significantly (p < 0.05), and simultaneously the red fluorescence gets significantly (p < 0.05) diminished (515 ± 113.2) after addition of HSO3−. The CM has been effectively utilized for evaluating the bisulfite ions in food samples as well. The concentrations of HSO3− in diluted sugar samples have been determined with the recovery of 97.6–9.12%.

Exploitation of a turn-on photoelectrochemical sensing platform based on Au/BiOI for determination of copper(II) ions in food samples

Copper is an essential element and plays an important role in various physiological processes. Therefore, it is critical to exploit novel assay for effective, rapid, simple and selective detection of copper. Herein, a cathodic turn-on photoelectrochemical (PEC) sensor was developed for the selective and accurate analysis of copper(II) ions (Cu2+) in food samples based on the gold nanoparticles (AuNPs) loaded BiOI nanocomposite (Au/BiOI). By screening and optimizing bismuth oxyhalide semiconductors, the Au/BiOI with a wide visible light response range and low electron recombination efficiency was prepared. Compared with the BiOI alone, the Au/BiOI exhibited about 4-hold enhanced photocurrent intensity. Based on the excellent PEC performances, the Au/BiOI were successfully applied to construct the Cu2+ PEC sensor. Under the optimized conditions, the Au/BiOI-based PEC sensor exhibited excellent linear response with the concentration of Cu2+ from 1 to 50 μM and a low limit of detection (0.4 μM). Moreover, this PEC sensing strategy exhibited a feasible method for Cu2+ detection in food samples with high selectivity and good stability.

Rapid potentiometric sensor for determination of Cu(II) ions in food samples

Copper is considered as one of the first metals used by humans. It is an essential trace element with great significance in the normal functioning and keeping of a large number of body systems. Developing selective, sensitive, and easily prepared sensors for the measurement of Cu(II) ions in different matrices is critical. This paper reports a new highly selective and sensitive Cu(II) ions modified carbon paste electrode (MCPE) based on 2-(3-phenoxy phenyl) propanoic acid (Fenoprofen (FP)) as a Cu(II) selective modifier. The developed MCPE exhibits a Nernstian slope of 29.9 ± 0.15 mV decade−1 in the linear range of 1.0 × 10−6 to 1.0 × 10−2 mol L−1 with a rapid response time of 6 s and pH-independency in the range of 3.0–5.0. The proposed MCPE showed a negligible change in the slope or the working range when the measurement was applied in a partially non-aqueous medium and showed high selectivity toward Cu(II) ions in comparison with numerous other cations. The applicability of the proposed MCPE for Cu(II) ions determination in various food samples was also examined. Furthermore, the morphology of the proposed MCPE surface was investigated using energy-dispersive X-ray (EDX) and scanning electron microscopic (SEM) to confirm the interaction between Cu(II) ions and FP.

A turn-on red-emitting fluorescent probe for determination of copper(II) ions in food samples and living zebrafish

Herein, we developed a turn-on red-emitting fluorescent probe for the sensitive and selective detection of copper ions (Cu2+) in food samples and living zebrafish. The probe employs a hemicyanine scaffold as the fluorophore and a 2-pyridinecarbonyl group as the recognition receptor and quenching moiety. The 2-pyridinecarbonyl moiety can be specifically cleaved by Cu2+ and results in an approximately 18-fold fluorescence enhancement of the probe, thereby providing a fluorescence turn-on assay for Cu2+. Additionally, the probe exhibited excellent selectivity, high sensitivity, a broad linear relationship (0.020 to 8.0 μM), and a low limit of detection (4.0 nM, S/N = 3) for Cu2+. Concomitantly, the probe exhibited satisfactory analytical performance when used with actual food samples. Moreover, the probe could be used for in situ determination of Cu2+ in both living plant tissues and in living zebrafish.

A new electrochemical sensor for simultaneous determination of Cd (II) and Pb (II) using FeNi3/CuS/BiOCl: RSM optimization

In this study, an electrochemical sensor has been made to detect Cd (II) and Pb (II) on the carbon electrode (CPE) modified with the FeNi3/CuS/BiOCl nanocomposite. In addition, we utilized square wave anodic stripping voltammograms (SWASV) technique to detect the target metal ions. Moreover, an experimental design has been used to examine and optimize the impacts of diverse experimental parameters like the pH of the solution, accumulation potential, accumulation time, and concentration of the nanocomposite as a modifier in CPE. As FeNi3, CuS and BiOCl nanoparticles (NPs) have synergetic effects, FeNi3/CuS/BiOCl/CPE presented very good mechanical stability and electrical conductivity in the presence of Pb (II) and Cd (II) ions. Upon the optimization of the conditions, the newly designed sensor exhibited completely wide linear ranges of 1.0 and 150.0 μg/L; and 0.5 to 120.0 μg/L and LOD 0.4 μg/L and 0.1 μg/L for Cd (II) and Pb (II), respectively. The modified CPE displayed considerable reliability, reproducibility, stability, and selectivity. Moreover, detecting cadmium (II) and lead (II) ions in food samples illustrated very good practicability of the new modified carbon paste.