Detection Of Trace Heavy Metals Research Articles

Sensitivity and stability improvement on slippery surface-aggregated substrate for trace heavy metals detection using NELIBS

The sensitive and stable detection of trace heavy metals in liquid is crucial given its profound impact on various aspects of human life. Currently, nanoparticle-enhanced laser-induced breakdown spectroscopy (NELIBS) with dried droplet method (DDM) is widely applied for heavy metals detection. Nevertheless, the coffee ring effect (CRE) in DDM affects the stability, accuracy, and sensitivity of NELIBS. Here, we developed a slippery surface-aggregated substrate (SS substrate) to suppress the CRE and enrich analytes, and form a plasmonic platform for NELIBS detection. The SS substrate was prepared by infiltrating perfluorinated lubricant into the pores of PTFE membrane. The droplet, with targeted elements and gold nanoparticles, was dried on the SS substate to form the plasmonic platform for NELIBS analysis. Then, trace heavy metal elements copper (Cu) and manganese (Mn) were analyzed by NELIBS. The results of Cu (RSD = 5.60%, LoD = 3.72 μg/L) and Mn (RSD = 7.42%, LoD = 6.37 μg/L), illustrated the CRE suppression and analytes enrichment by the SS substrate. The results verified the realization of stable, accurate and sensitive NELIBS detection. And the LoDs succeeded to reach the standard limit of China (GB/T 14848-2017). Furthermore, the results for groundwater detection (relative error: 5.92% (Cu) and 4.74% (Mn)), comparing NELIBS and inductively coupled plasma mass spectrometry (ICP-MS), validated the feasibility of the SS substrate in practical applications. In summary, the SS substrate exhibits immense potential for practical application such as water quality detection and supervision.

Studies on adsorption properties of magnetic composite prepared by one-pot method for Cd(II), Pb(II), Hg(II), and As(III): Mechanism and practical application in food

A one-pot synthesis afforded a magnetic, crosslinked polymer adsorbent (m-P6) with a variety of functional groups to realize simultaneous adsorption of Cd2+, Pb2+, Hg2+, and As3+. The material was characterized by TEM-EDS, XRD, FT-IR, VSM, and XPS. Kinetic and isothermal analyses suggested mainly chemisorption processes of heavy metal ions that form multiple layers on heterogeneous surfaces. Theoretical adsorption capacities calculated by a pseudo-2nd-order kinetic model and the Sips isothermal model were 282.88 mg/g for Cd2+, 326.18 mg/g for Pb2+, 117.85 mg/g for Hg2+, and 320.29 mg/g for As3+. m-P6 not only can efficiently adsorb divalent heavy metals (Cd2+, Pb2+, Hg2+), but also demonstrate a process of adsorption-driven catalytic oxidation by single-electron transfer (SET) from As3+ to As5+. In application, in addition to adsorption in water, m-P6 is capable of minimizing matrix interference, and extracting trace heavy metals in a complex environment (cereal) through easy operations for improving the detection accuracy, as well as it is potential for application in detection of trace heavy metals in foodstuffs. m-P6 can be readily regenerated and efficiently recycled for 5 cycles using eluent E12 and dilute acid.

Detection of heavy metal ions using laser-induced breakdown spectroscopy combined with filter paper modified with PtAg bimetallic nanoparticles.

The rapid and sensitive detection of heavy metal ions is important for environment and human health. Hence, the rapid and sensitive detection of multiple heavy metals simultaneously has become a critical issue. Here, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with filter paper modified with PtAg bimetallic nanoparticles (BNPs) (LIBS-FP-PtAgBNPs) for the ultrasensitive detection of Hg2+, Cr3+, and Pb2+. The PtAgBNPs-modified filter paper was used to efficiently and specifically adsorb Hg, Cr, and Pb, and LIBS was used to detect the Hg, Cr, and Pb simultaneously. The limits of detection for Hg, Cr, and Pb were 0.5μg/L (2.5nM), 8μg/L (0.15μM), and 2μg/L (9nM), respectively. Furthermore, this method was successfully applied to determine the concentrations of Hg, Cr, and Pb in real spiked water samples. Compared with other methods based on nanoparticle sensing, LIBS-FP-PtAgBNPs is simpler to use and can achieve highly efficient enrichment, rapid separation, and sensitive detection of heavy metal ions. The optimal detections of Hg, Cr, and Pb were achieved in the pH range of 1-6. The developed method provides a new avenue to realize the rapid and sensitive detection of trace heavy metals in the environment.

Three-dimensional porous high boron-nitrogen-doped carbon for the ultrasensitive electrochemical detection of trace heavy metals in food samples.

Exposure to even trace amounts of Cd(II) and Pb(II) in food can have serious effects on the human body. Therefore, the development of novel electrochemical sensors that can accurately detect the different toxicity levels of heavy metal ions in food is of great significance. Based on the principle of green chemistry, we propose a new type of boron and nitrogen co-doped carbon (BCN) material derived from a metal-organic framework material and study its synthesis, characterization, and heavy-metal ion detection ability. Under the optimum conditions, the BCN-modified glassy carbon electrode was studied using square-wave anodic stripping voltammetry, which showed good electrochemical responses to Cd(II) and Pb(II), with sensitivities as low as 0.459 and 0.509 μA/μM cm2, respectively. The sensor was successfully used to detect Cd(II) and Pb(II) in Beta vulgaris var. cicla L samples, which is consistent with the results obtained using inductively coupled plasma-mass spectrometry. It also has a strong selectivity for complex samples. This study provides a novel approach for the detection of heavy metal ions in food and greatly expands the application of heteroatom-doped metal-free carbon materials in detection platforms.

Simultaneous sensitive analysis of Cd(ii), Pb(ii) and As(iii) using a dual-channel anodic stripping voltammetry approach

A dual-channel anodic stripping voltammetry protocol is proposed for the simultaneous detection of trace heavy metals in one experiment with high sensitivity.

Zr/ZrO2 nanotube electrode for detection of heavy metal ions

An integrated system for photo-accumulation (photoreduction) and sensing, based on a Zr/ZrO2 electrode, has been developed for the detection of trace heavy metals. The nanostructuring of the Zr/ZrO2 electrode was achieved by anodizing, which produced a nanotubular structure. Solutions containing Cd(II), Pb(II), Cu(II) and Hg(II) were used for analysis. Linear calibration plots were obtained in the concentration ranges from 8 × 10−8 to 10−5 M for Pb(II), 5 × 10−8 to 2 × 10−6 M for Cu(II) and 4 × 10−8 to 10−5 M for Hg(II).

A rapid pretreatment of PVC products for high-throughput and visual detection of trace heavy metals

A novel method, based on modified silver nanoparticles, for high-throughput visual detection of heavy metal ions in polyvinyl chloride (PVC) products was developed including a key pretreatment process in which tetrahydrofuran was used to dissolve PVC powder samples quickly. Heavy metal ions were successfully transferred from THF to the aqueous phase by the liquid–liquid extraction method during the pretreatment procedures. Then, enriched Cu2+, Mn2+, and Cr3+ were detected by three kinds of silver nanoparticles (4-MBA-AgNPs, 4-MBA-MA-AgNPs, and 4-NBT/4-MBA-AgNPs) using naked eyes and microplate reader, respectively. The visual detection limits of Cu2+, Mn2+, and Cr3+ were 1.0 × 10−6 M, 1.0 × 10−7 M, and 1.0 × 10−6 M, while the detection limits of Cu2+, Mn2+, and Cr3+ were 2.5 × 10−8 M, 5.0 × 10−8 M, and 5.0 × 10−8 M using microplate reader, respectively. Apparently, the proposed method could provide a potent means in the practical detection of heavy metal ions in PVC products with advantages of low-cost, rapid, high-throughput, and on-site detection.

A dual-responsive biosensor for blood lead detection

Simple and accurate detection of trace heavy metals in blood is very important. A novel dual-responsive electrochemical/fluorescent biosensor based on magnetic hyperbranched polyamide with heparin modification (MHPAM-H) for blood lead detection has been successfully developed. Upon conjugated with blood lead ions, dual-biosensor could not only display electrochemical signal but also fluorescence signal owing to the enriched amino groups, cavity structure, and good fluorescence properties of HPAM. Blood biocompatibility, construction of the dual-responsive biosensor, electrochemical/fluorescent detection of lead ions in water phase and blood condition, selectivity and stability of the dual-responsive biosensor were investigated in detail. The proposed dual-responsive biosensor displays good linear relationship (1.5 pM- 4.8 × 103 pM for electrochemical detection and 0.5 pM-4.8 × 103 pM for fluorescent detection) with low detection limit (4.4 pM for electrochemical detection and 1.0 pM for fluorescent detection) for blood lead, providing potential application for blood lead detection in the future.

Detection of trace heavy metals using atmospheric pressure glow discharge by optical emission spectra

In this Letter, atmospheric pressure glow discharge based on a small discharge gap is excited by sine AC voltage in air on purpose of detecting trace heavy metal elements in solid samples, which makes the detection limits of trace heavy metal elements reach tens μg/kg. The waveforms of voltage and discharge current, discharge images, plasma gas temperature, and optical emission spectra are obtained to discuss the feasibility of atmospheric pressure glow discharge on detection of trace heavy metals. The formation mechanism of optical emission spectra and the strong emission intensity of heavy metal elements show that energetic electrons and excited metal atoms are easily generated by atmospheric pressure glow discharge. The effects of applied voltage and discharge gap on atmospheric pressure glow discharge are discussed to acquire the optimal experimental conditions. And a smaller discharge gap and applied voltage can restrain the transition from glow discharge to arc discharge. Besides, the limits of detections of Cu and Cd are about 0.0241 and 0.0318 μg/g, respectively, by using atmospheric pressure glow discharge with an applied voltage of 3.8 kV, discharge gap of 3.5 mm, and driving frequency of 10 kHz.

Signal enhancement of electrochemical DNA biosensors for the detection of trace heavy metals

Abstract Heavy-metal pollution has attracted intensive attention from the public because of the severe threats of heavy metals to the ecosystem and human health. Ultralow concentration of heavy metals in aquatic environment leads to the urgent needs of sensitive approaches for heavy-metal detection. Electrochemical DNA biosensors present outstanding superiority in convenience, selectivity, and sensitivity compared with conventional methods. To achieve the ultralow detection limit, efforts have been made to implement signal enhancement strategies to develop electrochemical DNA biosensors with enhanced sensing performance. This review focuses on the recent progress in signal enhancement strategies applied to electrochemical DNA biosensors for heavy-metal-ion detection including nicking enzyme–assisted amplification, the utilization of core–shell nanoparticles, and nanocomposites modification.

Modifier-Free Microfluidic Electrochemical Sensor for Heavy-Metal Detection.

Heavy-metal pollution poses severe threat to ecological systems and presents a great challenge for global sustainability. Portable point-of-care sensing platform for detection/monitoring of heavy-metal pollution in the environment is urgently demanded. Herein, a highly sensitive, robust, and low-cost microfluidic electrochemical carbon-based sensor (μCS) for detection of trace heavy metals is presented. The miniaturized μCS devices are based on a microfluidic paper channel combined with a novel three-dimensional layout with working and counter electrodes facing each other and analyte flowing along the microfluidic channel between these two electrodes. Pristine graphite foil free of any surface modifier is not only used as the electronically conductive pad but also directly employed as the working electrode for fabricating the μCS. The resulting simple and portable device was applied in Cd2+ and Pb2+ detection using square-wave anodic stripping voltammetry. Detection limits down to 1.2 μg/L for Cd2+ and 1.8 μg/L for Pb2+ can be achieved over the μCS. The μCS devices are also found to be highly robust, and 10 repetitive measurements with a single μCS device resulted to be highly reproducible.

Monitoring Technology of Trace Heavy Metals in Seawater Based on Spectrophotometry

This paper briefly describes the severity of the heavy metal pollution in seawater in recent years, and proposes a method for the detection of trace heavy metals in seawater based on spectrophotometric method. Establish water soluble trace Zn2+, Cu2+, Ni2+, and Cd2+ test system, first of all study the optimal measurementranges of each ion, and carry out the additive research. The experimental results show that Zn2+, Cu2+, Ni2+, and Cd2+ four kinds of metal ions total concentration is in the range of less than 1200 mu g/L and it is in agood degree; and then study the algorithm feasibility and accuracy of measurement, and compares with the ICP-OES measurement results. It also tests the performance of experiment measurement system, and the measurement results have good consistency.

Nanostructure Restoration of Thermally Reduced Graphene Oxide Electrode upon Incorporation of Nafion for Detection of Trace Heavy Metals in Aqueous Solution

AbstractHigh performance reduced graphene oxide (RGO)‐Nafion (N) thin film electrodes coated on silicon (Si) substrates (RGO‐N/Si) were successfully developed through thermal reduction of GO‐N without delamination from the substrates. The restoration of the RGO‐N nanostructure upon the addition of Nafion was proven by Raman spectroscopy (RS) and field emission scanning electron microscopy, and the restoration mechanism of the RGO‐N nanostructure was proposed. Through the investigation using x‐ray photoelectron spectroscopy (XPS), the polyfluorocarbon from Nafion possessed a function that could prevent the delamination of the RGO sheets from the substrates during the thermal reduction. The RGO‐N/Si samples were later used for the determination of trace heavy metals, such as divalent lead, cadmium and copper ions (Pb2+, Cd2+ and Cu2+, respectively) using square wave anodic stripping voltammetry in a 0.1 M acetate buffer solution (pH 5). Based on the electroanalytical measurements, the RGO‐N/Si samples exhibited a highly linear behavior in the detection of Cd2+, Pb2+ and Cu2+ over the concentration range of 50 nM to 300 nM with detection limits at nM levels. In addition, the RGO‐N/Si samples presented good recoveries of target metals in tap water samples.

HPLC-spectrophotometric detection of trace heavy metals via ‘cascade’ separation and concentration

A cascade pre-concentration and separation system involving continuous solid-phase extraction and one-drop solvent concentration was developed to enable high-performance liquid chromatography (HPLC) determination of trace levels of Ni(II), Co(II), Cu(II), Se(IV) and Cr(VI) ions in aqueous solution via complexation with sodium diethyldithiocarbamate. The metal complexes were almost completely adsorbed on the solid phase (octadecylsilyl packed column). Ethyl acetate (eluent) containing the metal complexes was then placed in a centrifuge tube, to which a microvolume of dimethyl sulfoxide (DMSO) was added. Successful pre-concentration of the metal complexes into the DMSO phase was accomplished by removing the ethyl acetate using a compact evaporator in a water bath (40°C); 1000-fold concentration was achieved within 45 min. A portion of the residual DMSO phase was then subjected to HPLC analysis. The proposed method has high reproducibility and high sensitivity with detection limits (3σ) for Ni(II), Co(II), Cu(II), Se(IV) and Cr(VI) ions of 0.08, 0.11, 0.12, 0.44 and 0.20 µg/L, respectively. Relative standard deviations (RSDs) (n = 5) at Ni(II) 5.87 µg/L, Co(II) 5.89 µg/L, Cu(II) 6.35 µg/L, Se(IV) 7.90 µg/L and Cr(VI) 5.20 µg/L (1.0 × 10−7 mol/L each) were 4.0%, 4.6%, 4.6%, 7.2% and 3.4%, respectively.

Novel cysteic acid/reduced graphene oxide composite film modified electrode for the selective detection of trace silver ions in natural waters

Novel cysteic acid/reduced graphene oxide composite film on a glassy carbon electrode has been prepared through the electrochemical oxidation of L-cysteine for silver sensing. Differential pulse anodic stripping voltammetry (DPASV) was employed for the detection of trace Ag(I) in aqueous solutions with the composite film modified electrode, which is referred to as an efficient method for the detection of trace heavy metals. We found the linear relationship between the peak current of the stripping voltammetry of Ag(I) and the concentration of Ag(I) in the range of 1.0 × 10−8 ∼ 2.0 × 10−4 M with a correlation coefficient R2 = 0.996, and the detection limit can be down to 1.0 × 10−9 M (S/N = 3). The as-developed cysteic acid/reduced graphene oxide composite film modified electrode demonstrated ultrahigh sensitivity, reproducibility and recovery for the selective detection of trace Ag(I) without any interference from other metal ions.

A new non-destructive method for chemical analysis of particulate matter filters: The case of manganese air pollution in Vallecamonica (Italy)

Total Reflection X-ray Fluorescence (TXRF) is a well-established technique for chemical analysis, but it is mainly employed for quality control in the electronics semiconductor industry. The capability to analyze liquid and uniformly thin solid samples makes this technique suitable for other applications, and especially in the very critical field of environmental analysis. Comparison with standard methods like inductively coupled plasma (ICP) and atomic absorption spectroscopy (AAS) shows that TXRF is a practical, accurate, and reliable technique in occupational settings. Due to the greater sensitivity necessary in trace heavy metal detection, TXRF is also suitable for environmental chemical analysis. In this paper we show that based on appropriate standards, TXRF can be considered for non-destructive routine quantitative analysis of environmental matrices such as air filters. This work has been developed in the frame of the EU-FP6 PHIME (Public Health Impact of long-term, low-level Mixed element Exposure in susceptible population strata) Integrated Project ( www.phime.org). The aim of this work was to investigate Mn air pollution in the area of Vallecamonica (Italy).

Electrochemical performances of B doped and undoped diamond-like carbon (DLC) films deposited by femtosecond pulsed laser ablation for heavy metal detection using square wave anodic stripping voltammetric (SWASV) technique

Pure diamond-like carbon (DLC) thin films and boron-doped DLC thin films have been deposited on silicon substrates using femtosecond pulsed laser. The amorphous carbon materials (DLC), have been deposited at room temperature by ablating graphite targets with an amplified Ti:sapphire laser of 800 nm wavelength and a pulse duration of 150 fs in high vacuum conditions. Doping with boron has been performed by ablating alternatively graphite and boron targets. In this study, the DLC films were used as working electrodes for the electrochemical detection of trace heavy metals namely, Cd 2+, Pb 2+, Ni 2+ and Hg 2+, by using square wave anodic stripping voltammetry (SWASV) technique. Four metals were detected at −1.3 V deposition potential, and 90 s deposition time. The DLC films have been characterized by multiwavelength Raman spectrometry and high resolution scanning electron microscopy. The effect of the boron doping on the electrochemical behavior has been shown. The a-C:B 8%/Si 3N 4 electrode gives the more sensitive detection. The four metals are detected simultaneously with a detection limit of 1 μg/L or 2 μg/L and a dynamic range from 1 or 2 to 25 μg/L for every metal, as presented in third table of this article. The different sensitivities obtained are 6.2, 20.0, 1.2 and 6.6 μA/ppb or μA μg −1 L for Cd 2+, Pb 2+, Ni 2+ and Hg 2+, respectively.

Fully electrochemical hyphenated flow system for preconcentration, cleanup, stripping, capillary electrophoresis with stacking and contactless conductivity detection of trace heavy metals

Successful coupling of electrochemical preconcentration (EPC) to capillary electrophoresis (CE) with contactless conductivity detection (C 4D) is reported for the first time. The EPC–CE interface comprises a dual glassy carbon electrode (GCE) block, a spacer and an upper block with flow inlet and outlet, pseudo-reference electrode and a fitting for the CE silica column, consisting of an orifice perpendicular to the surface of a glassy carbon electrode with a bushing inside to ensure a tight press fit. The end of the capillary in contact with the GCE is slant polished, thus defining a reproducible distance from the electrode surface to the column bore. First results with EPC–CE–C 4D are very promising, as revealed by enrichment factors of two orders of magnitude for Tl, Cu, Pb and Cd ion peak area signals. Detection limits for 10 min deposition time fall around 20 nmol L −1 with linear calibration curves over a wide range. Besides preconcentration, easy matrix exchange between accumulation and stripping/injection favors procedures like sample cleanup and optimization of pH, ionic strength and complexing power. This was demonstrated for highly saline samples by using a low conductivity buffer for stripping/injection to improve separation and promote field-enhanced sample stacking during electromigration along the capillary.