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As an ideal transition metal oxide, Co3O4 is a P-type semiconductor with excellent electrical conductivity, non-toxicity and low cost. This work reports the successful construction of Co3O4 materials derived from metal-organic frameworks (MOFs) using a surfactant micelle template-solvothermal method. The modified electrodes are investigated for their ability to electrochemically detect Pb2+ and Cu2+ in aqueous environments. By adjusting the mass ratios of alkaline modifiers, the morphological microstructures of Co3O4-X exhibit a transition from distinctive microspheres composed of fiber stacks to rods. The results indicate that Co3O4-1(NH4F/CO(NH2)2 = 1:0) has a distinctive microsphere structure composed of stacked fibers, unlike the other two materials. Co3O4-1/GCE is used as the active material of the modified electrode, it shows the largest peak response currents to Pb2+ and Cu2+, and efficiently detects Pb2+ and Cu2+ in the aqueous environment individually and simultaneously. The linear response range of Co3O4-1/GCE for the simultaneous detection of Pb2+ and Cu2+ is 0.5–1.5 μM, with the limits of detection (LOD, S/N = 3) are 9.77 nM and 14.97 nM, respectively. The material exhibits a favorable electrochemical response, via a distinctive Co3O4-1 microsphere structure composed of stacked fibers. This structure enhances the number of active adsorption sites on the material, thereby facilitating the adsorption of heavy metal ions (HMIs). The presence of oxygen vacancies (OV) can also facilitate the adsorption of ions. The Co3O4-1/GCE electrode also exhibits excellent anti-interference ability, stability, and repeatability. This is of great practical significance for detecting Pb2+ and Cu2+ in real water samples and provides a new approach for developing high-performance metal oxide electrochemical sensors derived from MOFs. [ABSTRACT FROM AUTHOR]

As an ideal transition metal oxide, Co3O4 is a P-type semiconductor with excellent electrical conductivity, non-toxicity and low cost. This work reports the successful construction of Co3O4 materials derived from metal-organic frameworks (MOFs) using a surfactant micelle template-solvothermal method. The modified electrodes are investigated for their ability to electrochemically detect Pb2+ and Cu2+ in aqueous environments. By adjusting the mass ratios of alkaline modifiers, the morphological microstructures of Co3O4-X exhibit a transition from distinctive microspheres composed of fiber stacks to rods. The results indicate that Co3O4-1(NH4F/CO(NH2)2 = 1:0) has a distinctive microsphere structure composed of stacked fibers, unlike the other two materials. Co3O4-1/GCE is used as the active material of the modified electrode, it shows the largest peak response currents to Pb2+ and Cu2+, and efficiently detects Pb2+ and Cu2+ in the aqueous environment individually and simultaneously. The linear response range of Co3O4-1/GCE for the simultaneous detection of Pb2+ and Cu2+ is 0.5–1.5 μM, with the limits of detection (LOD, S/N = 3) are 9.77 nM and 14.97 nM, respectively. The material exhibits a favorable electrochemical response, via a distinctive Co3O4-1 microsphere structure composed of stacked fibers. This structure enhances the number of active adsorption sites on the material, thereby facilitating the adsorption of heavy metal ions (HMIs). The presence of oxygen vacancies (OV) can also facilitate the adsorption of ions. The Co3O4-1/GCE electrode also exhibits excellent anti-interference ability, stability, and repeatability. This is of great practical significance for detecting Pb2+ and Cu2+ in real water samples and provides a new approach for developing high-performance metal oxide electrochemical sensors derived from MOFs. [ABSTRACT FROM AUTHOR]

A fluorescent multichannel sensor array has been established based on three carbon dots derived from Tibetan medicine waste for rapid quantification and discrimination of six heavy metal ions. Due to the chelation between metal ions and carbon dots (CDs), this fluorescence "turn off" mode sensing array can quantify six metal ions as low as "μM" level. Moreover, the six heavy metal ions display varying quenching effects on these three CDs owing to diverse chelating abilities between each other, producing differential fluorescent signals for three sensing channels, which can be plotted as specific fingerprints and converted into intuitive identification profiles via principal component analysis (PCA) and hierarchical cluster analysis (HCA) technologies to accurately distinguish Cu2+, Fe3+, Mn2+, Ag+, Ce4+, and Ni2+ with the minimum differentiated concentration of 5 μM. Valuably, this sensing array unveils good sensitivity, exceptional selectivity, ideal stability, and excellent anti-interference ability for both mixed standards and actual samples. Our contribution provides a novel approach for simultaneous determination of multiple heavy metal ions in environmental samples, and it will inspire the development of other advanced optical sensing array for simultaneous quantification and discrimination of multiple targets. [ABSTRACT FROM AUTHOR]

Titanium carbide quantum dots (Ti3C2 QDs) were synthesized by ammonia-assisted hydrothermal method. We also synthesized potassium permanganate (KMnO4)–functionalized Ti3C2 QDs (Mn-QDs) by modifying Ti3C2 nanosheets with KMnO4 and then cutting the functional nanosheets into Mn-QDs. The Ti3C2 QDs and Mn-QDs were characterized by fluorescence spectroscopy (FL), Fourier transform infrared spectroscopy (FTIR), UV–vis spectrophotometry (UV–vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Furthermore, the modified Mn-QDs have strong luminescence ability and good dispersion stability, which can be used for Cr3+ and Hg2+ double ion detection with enhanced fluorescence specificity. Cr3+/Hg2+ and negatively charged Mn-QDs are bound together by electrostatic interactions. Meanwhile, the surface of Mn-QDs is rich in functional groups, which interacts with Cr3+/Hg2+ to modify the surface traps, leading to defect passivation and exhibiting photoluminescence enhancement. For the dynamic quenching produced by the interaction of Mn-QDs with Hg2+ within 50 μM, it may be caused by the complex formation of Hg2+ trapped by the amino group on the surface of Mn-QDs. The detection limits for Cr3+ and Hg2+ were 0.80 μM and 0.16 μM, respectively. The recoveries of Cr3+ and Hg2+ ions in real water samples were 93.79–105.10% and 93.91–102.05%, respectively, by standard addition recovery test. In this work, the application of Mn-QDs in Cr3+ and Hg2+ ion detection was researched, which opens a new way for its application in the field of detecting heavy metal ions. [ABSTRACT FROM AUTHOR]

A complex [Co4(TCTA)2(H2O)8]∙10H2O (Co-TCTA) based on thiacalix[4]arene derivative has been synthesized for the first time using the solvothermal method. The glassy carbon electrode (GCE) modified with Co-TCTA (Co-TCTA/GCE) could simultaneously determine Cd2+, Pb2+, and Cu2+ at around − 0.75 V, − 0.60 V, and − 0.10 V (vs. ref. Ag/AgCl) and had good stability, selectivity, and reproducibility with relative standard deviation (RSD) of 4.4% for Cd2+, 1.4% for Pb2+, and 5.4% for Cu2+. Co-TCTA/GCE showed wide linear range of 0.4–8.0 μM for Cd2+, 0.4–7.0 μM for Pb2+, and 0.6–6.0 μM for Cu2+ when three ions were determined simultaneously. The limits of detection (LODs) of Cd2+, Pb2+, and Cu2+ were 0.071 μM, 0.022 μM, and 0.021 μM, respectively. Moreover, the sensor was used to determine three ions in lake water sample with satisfactory recoveries of 93.6–93.8% for Cd2+, 93.8–103.3% for Pb2+ and 94.6–95.3% for Cu2+. The good adsorption capacity of Co-TCTA and Co(II)/Co(0) circular mechanism on the surface of the electrode were proposed to enhance the electrochemical signals. This work enriched the theoretical research on the complexes for the determination of heavy metal ions. [ABSTRACT FROM AUTHOR]

A fluorometric assay was developed for the determination of copper(II) ion based on its quenching effect on the green fluorescent probe of SiO2-anchored CdS nanocrystals (SiO2/CdS NCs). The fluorescent probe was prepared by a surface ion-directing strategy for homogeneous precipitation of CdS NCs onto the carboxyl-capped SiO2 core surfaces. In comparison to CdS NCs, the SiO2/CdS NCs has strong fluorescence emission and good photostability. Moreover, SiO2/CdS NCs show higher fluorescence selectivity for copper(II) ions than for other common metal ions because copper(II) ions have a strong fluorescence quenching effect on SiO2/CdS NCs. At excitation/emission wavelengths of 300/516 nm, the resulting fluorescent probe shows wide linear ranges from 0.01 to 2 μM with a detection limit of 6.3 nM for copper(II) ions. The method has been applied to the determination of trace copper(II) ions in tea infusions with satisfactory results. [ABSTRACT FROM AUTHOR]

An electrochemical sensor is described for the simultaneous determination of Cd2+, Cu2+, Hg2+ and Pb2+ using square wave anodic stripping voltammetry. A glassy carbon electrode (GCE) was modified with N,N-dimethyl-N-2-propenyl-2-propen-1-aminium chloride homopolymer ionic liquid doped into magnesium(II)-aluminium(III) layered double hydroxides. The morphology investigations suggest that the material possesses typical interconnected laminated micropores and a mesoporous architecture dispersed on the surface of the GCE. This accelerates mass diffusion and facilitates the deposition-stripping process of metal ions. Key operational parameters including pH, deposition potential, deposition time and the quantity of nanomaterial on the GCE were optimized. The following figures of merit for the ions Cd2+, Cu2+, Hg2+ and Pb2+ are obtained under optimum conditions: (a) detection limits of 250, 25, 250 and 16 ng L−1; (b) linear ranges from 0.5 to 20, 0.05 to 20, 0.5 to 20 and 0.05 to 20 μg L−1, and (c) peak potentials of −768, +42, +302 and − 541 mV (vs. Ag/AgCl). The modified GCE was successfully applied to the determination of these ions in spiked black tea extract and in dried tangerine peel. [ABSTRACT FROM AUTHOR]

A delaminated MXene-bismuth (Bi@d-Ti3C2) nanocomposite was synthesized for the construction of a microgrid electrochemical sensor via mechanical milling. The Bi@d-Ti3C2 nanocomposite was synthesized by accumulation of Bi(III) on the surface of delaminated Ti3C2 nanosheets through electrostatic attraction and subsequent in-situ growth of bismuth nanorods. Under optimized experimental conditions, the sensor exhibits (a) linear responses to Pb(II), Cd(II) and Zn(II) in the concentration range from 1 to 20 μg L−1, (b) well separated peak potentials at −0.54 V, −0.76 V and − 1.15 V vs. Ag/AgCl, (c) sensitivities of 0.98, 0.84 and 0.60 μA L μg−1, and (d) detection limits of 0.2, 0.4 and 0.5 μg L−1, respectively. This performance is attributed to the uniform dispersion of Bi nanorods on electrically conductive delaminated Ti3C2 MXene, and to the enhanced diffusion due to the microgrid structure. [ABSTRACT FROM AUTHOR]

The authors report on a disposable sensor for the differential pulse anodic stripping voltammetric (DPASV) determination of the ions Zn(II), Pb(II) and Cu(II). Simultaneous detection is accomplished by using a screen-printed carbon electrode (SPCE) co-modified with an in-situ plated bismuth (Bi)) film and gold nanoparticles (AuNPs). The synergistic effect of the Bi film, and the large surface and good electrical conductivity of the AuNPs strongly assist in the co-deposition of the three ions. Four well-defined and fully separated anodic stripping peaks, at 540 mV for Zn(II), 50 mV for Pb(II), 140 mV for Bi(III) and 295 mV for Cu(II), all vs. Ag/AgCl, can be seen. The modified SPCE was characterized by scanning electron microscopy, X-ray diffraction, cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimized conditions, the sensor has a good response to these ions. The detection limits (at an S/N ratio of 3) are 50 ng·L for Zn(II), 20 ng·L for Pb(II), and 30 ng·L for Cu(II). The method was applied to the determination of the 3 ions in spiked lake water samples. [ABSTRACT FROM AUTHOR]

An amino acid derived ionic liquid, FeO nanoparticles and graphene oxide (GO) were used to prepare a material for the magnetic solid phase extraction (MSPE) of the ions Al(III), Cr(III), Cu(II) and Pb(II). The material was characterized by Fourier transform infrared spectral (FT-IR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), magnetic analysis and isoelectric point (pI) analysis. It is shown to be a viable sorbent for the separation of these metal ions. Single factor experiments were carried out to optimize adsorption including pH values, ionic strength, temperature and solution volume. Following desorption with 0.1 M HCl, the ions were quantified by inductively coupled plasma optical emission spectrometry. Under the optimum conditions, the method provides a linear range from 10 to 170 μg· L for Al(III); from 4.0 to 200 μg· L for Cr(III); from 5.0 to 170 μg· L for Cu(II); and from 5.0 to 200 μg· L for Pb(II). The limits of detection (LOD) are 6.2 ng L for Al(III); 1.6 ng L for Cr(III); 0.52 ng L for Cu(II); and 30 ng L for Pb(II). Method performance was investigated by determination of these ions in (spiked) environmental water and gave recoveries in the range of 89.1%-117.8%. [ABSTRACT FROM AUTHOR]

The authors describe an ultra-sensitive approach for the determination of lead(II) by using a lead-specific aptamer and a fluorophore derived from perylenetetracarboxylic acid diimide (PTCDI). The fluorescence of PTCDI, with excitation/emission peaks at 494/543 nm, is quenched by the aptamer but restored if the aptamer binds lead(II). A detection scheme has been worked out that has a 0.1 ng·mLlimit of detection and a dynamic range that extends from 0.1 ng·mL to 10 μg·mL. The assay also demonstrates high selectivity for lead ions over nine other ions due to the aptamer's high specificity. The method shows a average recovery of 77.2-93.4% with an RSD of less than 3% in water samples. [ABSTRACT FROM AUTHOR]

This review (with 172 references) highlights the progress made in the past 10 years in silica sol-gel-based materials for use in optical chemical sensing. Following an introduction, the processes leading to the sol-gel-based and ormosil materials, their printability and methods for characterisation are discussed. Then various classes of optical sensors, with a focus on sensors for pH values, oxygen, carbon dioxide, ammonia (also in dissolved form), and heavy metal ions are described. A further section covers nanoparticle-based optical sensors mainly for use in intracellular sensing of the above species. Recent developments in this area are also emphasised and future trends discussed. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Heavy metals such as lead, mercury, cadmium, zinc and copper are among the most important pollutants because of their non-biodegradability and toxicity above certain thresholds. Here, we review methods for sensing heavy metal ions (HMI) in water samples using screen-printed electrodes (SPEs) as transducers. The review (with 107 refs.) starts with an introduction into the topic, and this is followed by sections on (a) mercury-coated SPEs, (b) bismuth-coated SPEs, (c) gold-coated SPEs (d) chemically modified and non-modified carbon SPEs, (e) enzyme inhibition-based SPEs, and (f) an overview of commercially available electrochemical portable heavy metal analyzers. The review reveals the significance of SPEs in terms of decentralized and of in situ analysis of heavy metal ions in environmental monitoring. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Magnetite (FeO) nanoparticles were coated with tannic acid to give nanoparticles (NPs) of the type FeO@TA and are shown to be a viable sorbent for preconcentration of Cd, Co and Cr. The size, morphology, composition, and properties of the FeO@TA NPs were characterized by field emission scanning electron microscopy, energy-dispersive X-ray analysis, vibrating sample magnetometery and FTIR. They were applied to the solid-phase extraction of the metal ions from environmental water samples prior to their quantitation by flow injection inductively coupled plasma-optical emission spectrometry. The effects of sample solution, extraction and desorption times, kind of eluent and quantity of sorbent were optimized. The calibration plots are linear in the concentration ranges from 0.5 to 100 μg L (for both Cd and Co) and from 0.2 to 100 μg L (for Cr). The limits of detection are between 0.1 and 0.2 μg L. The intra-day relative standard deviations based on four replicates are in the range of 6.1 to 7.1 %. The method was successfully applied to the determination of the three metal ions in (spiked) tap water, mineral water, and river water. Recoveries varied in the range from 90 to 109 %, this confirming the good performance of the method. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We report that magnetic multiwalled carbon nanotubes functionalized with 8-aminoquinoline can be applied to the preconcentration of Cd(II), Pb(II) and Ni(II) ions. The parameters affecting preconcentration were optimized by a Box-Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount, and pH value) were selected as the main factors affecting sorption, and four variables (type, volume and concentration of the eluent; elution time) were selected for optimizing elution. Following sorption and elution, the ions were quantified by FAAS. The LODs are 0.09, 0.72, and 1.0 ng mL for Cd(II), Ni(II), and Pb(II) ions, respectively. The relative standard deviations are <5.1 % for five separate batch determinations at 30 ng mL level of Cd(II), Ni(II), and Pb(II) ions. The sorption capacities (in mg g) of this new sorbent are 201 for Cd(II), 150 for Pb(II), and 172 Ni(II). The composite was successfully applied to the rapid extraction of trace quantities of heavy metal ions in fish, sediment, soil, and water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We describe a novel magnetic metal-organic framework (MOF) prepared from dithizone-modified FeO nanoparticles and a copper-(benzene-1,3,5-tricarboxylate) MOF and its use in the preconcentration of Cd(II), Pb(II), Ni(II), and Zn(II) ions. The parameters affecting preconcentration were optimized by a Box-Behnken design through response surface methodology. Three variables (extraction time, amount of the magnetic sorbent, and pH value) were selected as the main factors affecting adsorption, while four variables (type, volume and concentration of the eluent; desorption time) were selected for desorption in the optimization study. Following preconcentration and elution, the ions were quantified by FAAS. The limits of detection are 0.12, 0.39, 0.98, and 1.2 ng mL for Cd(II), Zn(II), Ni(II), and Pb(II) ions, respectively. The relative standard deviations were <4.5 % for five separate batch determinations of 50 ng mL of Cd(II), Zn(II), Ni(II), and Pb(II) ions. The adsorption capacities (in mg g) of this new MOF are 188 for Cd(II), 104 for Pb(II), 98 Ni(II), and 206 for Zn(II). The magnetic MOF nanocomposite has a higher capacity than the FeO/dithizone conjugate. This magnetic MOF nanocomposite was successfully applied to the rapid extraction of trace quantities of heavy metal ions in fish, sediment, soil, and water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We are presenting a strategy for the fabrication of disposable screen-printed electrodes modified with mercury nano-droplets and capable of sensing heavy metal ions. They were prepared by coating electrodes with a mixture of multi-walled carbon nanotubes and chitosan, this followed by adsorption of mercury. The resulting sensor was characterized by cyclic voltammetry and impedance spectroscopy. Also the effects caused by adsorption of mercury were investigated. It is shown that square wave anodic stripping voltammetry enables simultaneous determination of cadmium(II), lead(II) and copper(II), for which detection limits of 12, 23 and 20 nM, respectively, are found. Relative standard deviations for ten determinations at 0.6 µM concentrations of these ions are in the range of 3.0 to 5.7%. The applicability was tested by analyzing river water and showed recoveries between 94.1 and 104.6%, thus demonstrating its utility for in-field monitoring of these heavy metal ions. [ABSTRACT FROM AUTHOR]

A new method for the simultaneous determination of heavy metal ions in Chinese herbal medicine by microwave digestion and reversed-phase high-performance liquid chromatography (RP-HPLC) has been developed. The Chinese herbal medicine samples were digested by microwave digestion. Lead, cadmium, mercury, nickel, copper, zinc, and tin ions in the digested samples were pre-column derivatized with tetra-(4-chlorophenyl)-porphyrin (T4-CPP) to form the colored chelates which were then enriched by solid phase extraction with C18 cartridge and eluted from the cartridge with tetrahydrofuran (THF). The chelates were separated on a Waters Xterra ™RP18 column by gradient elution with methanol (containing 0.05 mol L-1 pyrrolidine-acetic acid buffer salt, pH=10.0) and THF (containing 0.05 mol L-1 pyrrolidine-acetic acid buffer salt, pH=10.0) as mobile phase at a flow rate of 0.5 mL min-1 and detected with a photodiode array detector in the range of 350–600 nm. In the original samples the detection limits of lead, cadmium, mercury, nickel, copper, zinc and tin are 4 ng L-1, 3 ng L-1, 6 ng L-1, 5 ng L-1, 2 ng L-1, 6 ng L-1, and 4 ng L-1, respectively. This method was applied to the determination of lead, cadmium, mercury, nickel, copper, zinc and tin in Chinese herbal medicine samples with good results. [ABSTRACT FROM AUTHOR]

A new fiber optical reflectance sensor for determination of heavy metal ions is described. It is based on xylenol orange which is electrostatically immobilized on an anion-exchange resin. The sensor was tested for lead ions. It is sensitive to Pb ions in a concentration range from 3 × 10 − 3 × 10 M. A response time of 1.5-2 min was observed. The optrode is not fully reversible, but can be regenerated in acidic solution (pH 1). [ABSTRACT FROM AUTHOR]

Polyaniline and its composites with nanoparticles have been widely used in electrochemical sensor and biosensors due to their attractive properties and the option of tuning them by proper choice of materials. The review (with 191 references) describes the progress made in the recent years in polyaniline-based biosensors and their applications in clinical sensing, food quality control, and environmental monitoring. A first section summarizes the features of using polyaniline in biosensing systems. A subsequent section covers sensors for clinical applications (with subsections on the detection of cancer cells and bacteria, and sensing of glucose, uric acid, and cholesterol). Further sections discuss sensors for use in the food industry (such as for sulfite, phenolic compounds, acrylamide), and in environmental monitoring (mainly pesticides and heavy metal ions). A concluding section summarizes the current state, highlights some of the challenges currently compromising performance in biosensors and nanobiosensors, and discusses potential future directions. [ABSTRACT FROM AUTHOR]

A quick and sensitive method was developed for the trace determination of Cd(II), Pb(II) and Cu(II) ions in water and bean samples. It is based on a combination of magnetic solid phase extraction (MSPE) and graphite furnace atomic absorption spectrometry (GFAAS). Allylthiourea (which contains abundant sulfur and nitrogen atoms) was copolymerized with ethylene dimethacrylate on the surface of magnetite (Fe3O4) nanoparticles to prepare a new adsorbent for use in MSPE. Various technologies were used to characterize the morphology, spectroscopic and magnetic properties of the adsorbent, and several parameters that affect the extraction performance were optimized. The adsorbent can enrich Cd(II), Pb(II) and Cu(II) ions via chelation interaction. Following elution with 0.1 mol·L−1 HNO3, the ions were quantified by GFAAS. Under the most favorable conditions, the limits of detection are from 3.3-7.2 ng·L−1 for water samples, and 1.1-1.5 μg·kg−1 for beans. The method displays wide linear analytical ranges and good precision. It was successfully applied to the determination of the metal ions in water and bean samples. The recoveries from spiked samples ranged between 80.5 and 114% in water, and from 82.2 to 118% in bean samples. The relative standard deviations of reproducibility were < 10%.Schematic presentation of the magetic solid phase extraction (MSPE) for the analysis of Cd(II), Pb(II) and Cu(II). MNP: magnetic nanoparticles; ATED: allylthiourea ethylene dimethacrylate copolymer [ABSTRACT FROM AUTHOR]

Water-soluble fluorescent polymer dots (PDs) were prepared from polyethylenimine and glutathione and are shown to be viable fluorescent probes for selective and sensitive determination of Hg(II). The PDs possess bright blue fluorescence (with excitation/emission peaks at 340/462 nm) which is quenched on addition of Hg(II). Based on these findings, a fluorometric assay was worked out. Fluorescence linearly drops in the 0.1 to 100 μM Hg(II) concentration range, and the limit of detection is 32 nM.The fluorescence of polymer dots prepared from glutathione and polyethyleimine (G-PEI PDs) is selectively quenched by Hg2+, and this finding was applied to the determination of Hg2+ in environmental water samples. [ABSTRACT FROM AUTHOR]

Various carbon nanomaterials for use in anodic stripping voltammetric analysis of Hg(II), Cu(II), Pb(II) and Cd(II) are screened. Graphene, carbon nanotubes, carbon nanofibers and fullerene (C60), dispersed in chitosan (Chit) aqueous solution, are used to modify a glassy carbon electrode (GCE). The fullerene-chitosan modified GCE (C60-Chit/GCE) displays superior performance in terms of simultaneous determination of the above ions. The electrodes and materials are characterized by electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The excellent performance of C60-Chit/GCE is attributed to the good electrical conductivity, large surface area, strong adsorption affinity and unique crystalline structure of C60. Using differential pulse anodic stripping voltammetry, the assay has the following features for Hg(II), Cu(II), Pb(II) and Cd(II), respectively: (a) Peak voltages of +0.14, −0.11, −0.58 and − 0.82 V (vs SCE); (b) linear ranges extending from 0.01-6.0 μM, 0.05-6.0 μM, 0.005-6.0 μM and 0.5-9.0 μM; and (c), detection limits (3σ method) of 3 nM (0.6 ppb), 14 nM (0.9 ppb), 1 nM (0.2 ppb) and 21 nM (2.4 ppb). Moreover, the modified GCE is well reproducible and suitable for long-term usage. The method was successfully applied to the simultaneous determination of these ions in spiked foodstuff.Compared with graphene, carbon nanotubes and carbon nanofibers, an electrode modified with fullerene in chitosan electrode displays superior performance for the simultaneous anodic stripping voltammetric detection of Hg(II), Cu(II), Pb(II) and Cd(II). [ABSTRACT FROM AUTHOR]