Simultaneous Determination Of Heavy Metals Research Articles

Short-End Injection Capillary Electrophoresis and Multivariate Analysis for Simultaneous Determination of Heavy Metals in Passiflora incarnata Tea.

An ultra-fast method for the simultaneous determination of heavy metals in Passiflora incarnata tea by capillary electrophoresis (CE) using a short-end injection combined with multivariate analysis was proposed. Separation was conducted by hydrodynamic injection (5 s at 0.5 psi) using the short-end injection procedure in a fused uncoated silica capillary (50 cm total length, 10.2 cm effective length, 50 µm i.d.) with separation time less than 2 min. An indirect UV detection at 214 nm was employed by using imidazole as a chromophore. The buffer used was 6 mmol/L hydroxybutyric acid (HIBA). The optimum conditions by full factorial with a central point were achieved by 18-crown-6 concentration (23.3 mmol L−1), voltage (+11.4 kV), methanol concentration (3.8%), and temperature (20 °C). The method showed good linearity (R2 > 0.998) for both Cd and Pb, inter-day precision of less than 14.49%, and an adequate limit of quantification only for Cd (LOQ < 0.5 µg mL−1 for Cd) based on the US Pharmacopeial Convention limit requirements for elemental impurities. After method validation, the method was applied to Passiflora incarnata tea samples from a local market. Furthermore, the developed method showed great potential for the determination of metals in other samples with proper sample preparation procedures.

Simple, fast and simultaneous determination of heavy metals in hair samples by SPE coupled with capillary electrophoresis

ABSTRACT A novel, simple, fast and sensitive method for the simultaneous analysis of heavy metals such as Cd(II), Cr(III), Co(II), Pb(II) and Cu(II) in hair samples based on complexometric method with EDTA and using solid-phase extraction with graphene oxide coupled with capillary electrophoresis has been developed. Under the optimised conditions, the proposed methodology had limits of detection from 5.7 to 16.8 µg kg−1 with intra- and inter-day repeatabilities <5% (in respect to relative standard deviation) in all cases. The proposed method was successfully employed for determination of heavy metals in the analysis of 20 hair samples. All samples were positive for at least one of the heavy metals studied with concentrations of 1.2 ± 1.0 mg kg−1 Cd(II), 7.2 ± 4.0 mg kg−1 Cr(III), 0.9 ± 0.8 mg kg−1 Co(II), 0.6 ± 0.2 mg kg−1 Pb(II) and 2.5 ± 0.3 mg kg−1 Cu(II). The method is an easy, robust and efficient strategy for determination of heavy metals in complex matrices.

A novel electrochemical sensor based on EDTA-NQS/GC for simultaneous determination of heavy metals

In this paper, we present a simple, sensitive and low-cost electrochemical sensor based on an organic layer of EDTA-NQS (1,2-napthaquinone-4 sulphonic acid sodium salt) formed on the surface of a glassy carbon electrode (GC) for the first time. The electrochemical characteristics of the newly fabricated EDTA-NQS/GC sensor were investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques. Experimental results confirmed that the new sensor showed superior analytical performance for the simultaneous detection of heavy metals trace in well separated anodic peaks even in the existence of some interfering species. The peak potentials for Cd2+, Pb2+, and Cu2+ are - 0.842, - 0.795 and - 0.285 V (vs. Ag/AgCl), respectively. In addition, it is sensitive to detect some transitional elements like Fe3+ and Hg2+ at - 0.027 and + 0.206 V. The detection limit for Cu2+ and Pb2+ was estimated to be 10.2 and 15.4 nM, respectively. Eventually, the developed sensor was successfully applied to detect contaminants in various cosmetic samples. A mechanism for sensing model has been proposed and discussed.

Simultaneous determination of heavy metals and cationic dyes from industrial effluent by prawn shell derived chitosan-g-poly (acrylic acid) biocomposite

Simultaneous determination of heavy metals and cationic dyes from industrial effluent by prawn shell derived chitosan-g-poly (acrylic acid) biocomposite

Simultaneous determination of heavy metals by an electrochemical method based on a nanocomposite consisting of fluorinated graphene and gold nanocage.

Fluorinated graphene/gold nanocage (FGP/AuNC) nanocomposite was developed for simultaneous determination of heavy metals using square wave anodic stripping voltammetry. Under optimized conditions, with a buffer pH of 5.0, a deposition potential of - 1.25V, and a deposition time of 140s, the method can obtain the best results. The FGP/AuNC electrode exhibits low limits of detection (0.08, 0.09, 0.05, 0.19, 0.01μgL-1), wide linear ranges (6-7000, 4-6000, 6-5000, 4-4000, 6-5000μgL-1), and well-separated stripping peaks (at - 1.10, - 0.77, - 0.50, - 0.01, 0.31V vs Ag/AgCl) towards Zn2+, Cd2+, Pb2+, Cu2+, and Hg2+, respectively. Furthermore, the FGP/AuNC electrode is also used forsimultaneous determination of Zn2+, Cd2+, Pb2+, Cu2+, and Hg2+ in real samples (peanut, rape bolt, and tea). Highly consistent results are found between the electrochemical method and atomic fluorescence spectrometry/inductively coupled plasma-mass spectrometry. The method has been successfully applied to the determination of heavy metal ions in agricultural food. Graphical abstract Schematic representation of simultaneous determination of heavy metal ions by electrochemical method. The FGP/AuNC (fluorinated graphene/gold nanocage) electrode is used to simultaneous determination of Zn2+, Cd2+, Pb2+, Cu2+, and Hg2+ by square wave anode stripping voltammetry.

SCREEN PRINTED ELECTRODE OF CARBON NANOTUBES MODIFIED WITH GOLD NANOPARTICLES FOR SIMULTANEOUS DETERMINATION OF ZINC, LEAD AND COPPER

Differential pulse anodic stripping voltammetry, method used for simultaneous determination of zinc, copper and lead with screen printed electrode of carbon nanotubes modified with gold nanoparticles was investigated. The results indicate that a simultaneous identification and quantification of zinc, lead and copper is possible at -0.6 V, -0.26 V and 0.16 V respectively. The maximum current was linearly dependent on the concentration of Zn2+, Pb2+ and Cu2+, thus allowing the construction of analytical curves, being: -Ip (A) = 0.08 + 0.214 [Zn2+ (g L-1)] in a range of 9.9 to 120 mg L-1 with an R2 = 0.993; -Ip (A) = -1.06 + 0.240 [Pb2+ (mg L-1)] in a range of 9.9 to 120 mg L-1 with an R2 = 0.998; -Ip (A) = -10.93 + 15.16 [Cu2+ (mg L-1)] in a range of 0.99 to 12 mg L-1 with an R2 = 0.998. The limits of detection and quantification were estimated between 1.0 - 3.5 mg L-1 for Zn2+, 1.5 - 5.0 mg L-1 for Pb2+ and 0.1 - 0.33 mg L-1 for Cu2+. An integral, selective and reliable system for simultaneous determination of heavy metals was achieved, which may have applications in field monitoring for environmental use and public health.

Electrochemical Sensors for Heavy Metals Detection in Gracilaria corticata using Multiwalled Carbon Nanotubes Modified Glassy Carbon Electrode

Electrochemical methods for heavy metals detection have attracted considerable attention due to their simplicity, rapidity and high sensitivity. Voltammetric methods are a valid and very effective alternative for the simultaneous determination of heavy metals. An independent atomic absorption spectroscopic analysis of the seaweed sample was carried out and the results were compared with the World Health Organization permissible limits. The sample was clearly observed in the atomic force microscopic images, characterized by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The electrochemical behavior of heavy metals on a bare glassy carbon electrode and a multiwalled carbon nanotubes modified glassy carbon electrode was studied by cyclic voltammetry, linear sweep anodic voltammetry, square wave anodic voltammetry and differential pulse anodic voltammetry. Very good responses were observed for all the metals when the modified electrode was employed.

Multifunctional Bismuth Oxychloride/Mesoporous Silica Composites for Photocatalysis, Antibacterial Test, and Simultaneous Stripping Analysis of Heavy Metals.

The increasing complexity of environmental pollution nowadays poses a severe threat to the public health, which attracts considerable attentions in searching for nanomaterials of multiproperty. In this study, mesoporous silica of KIT-6-encapsulated bismuth oxychloride (BiOCl), an intrinsically multifunctional material exhibiting bunched structure in the composites, are facilely prepared under hydrothermal conditions. Subsequently, the produced materials of multifunctionality were applied for photocatalysis, antibacterial test, and simultaneous determination of heavy metals including lead and cadmium. A combination of physiochemical characterizations have revealed that the BiOCl–KIT-6 composites exhibit enlarged yet refined surface morphology contributing to the improved photocatalytic ability with a band gap of 3.06 eV at a molecular ratio of 8Bi–Si. Moreover, the antibacterial activities of our BiOCl–KIT-6 composites were explored, and possible antimicrobial mechanism related to the production of reactive oxygen species was discussed. Furthermore, a sensitive electrochemical determination of heavy metals of lead and cadmium using square-wave anodic stripping voltammetry was also achieved. The composites-modified glassy carbon electrode displays a linear range of calibration curve from 0.2 to 300 μg/L with a detection limit of 0.05 μg/L (Pb2+) and 0.06 μg/L (Cd2+), respectively.

Graphene Oxide‐Modified Electrode Coated with in‐situ Antimony Film for the Simultaneous Determination of Heavy Metals by Sequential Injection‐Anodic Stripping Voltammetry

AbstractThe proposed chemically modified electrode was graphene oxide that was synthesized via Hummer's method followed by reduction of antimony film by in‐situ electrodeposition. The experimental process could be concluded in three main steps: preparation of antimony film, reduction of analyte ions on the electrode surface and stripping step under the conditions of square wave anodic stripping voltammetry (SWASV). A simple and rapid approach was developed for the determination of heavy metals simultaneously based on a sequential injection (SI), an automated flow‐based system, coupled with voltammetric method using antimony‐graphene oxide modified screen‐printed carbon electrode (SbF‐GO‐SPCE). The effects of main parameters involved with graphene oxide, antimony and measurement parameters were also investigated. Using SI‐SWASV under the optimal conditions, the proposed electrode platform has exhibited linear range from 0.1 to 1.5 M. Calculated limits of detection were 0.054, 0.026, 0.060, and 0.066 μM for Cd(II), Pb(II), Cu(II) and Hg(II), respectively. In addition, the optimized method has been successfully applied to determine heavy metals in real water samples with acceptable accuracy of 94.29 – 113.42 % recovery.

On-site detection of heavy metals in agriculture land by a disposable sensor based virtual instrument

A field-based detection system was designed and implemented for the simultaneous determination of heavy metals in soil samples. The detection principle is based on electrochemical differential pulse anodic stripping voltammetry (DPASV). In order to fulfill the requirements of field screening usage, a fast soil pretreatment process using ultrasonic-assisted extraction was applied. A disposable and integrated sensor, incorporating a three-electrode configuration (working electrode, reference electrode and counter electrode), was fabricated by the screen-printing technology and further modified with Nafion polymer and bismuth film. Coupled with the portable and flexible analysis instrument which was developed by virtual instrument technology, this system was used for trace determination of cadmium and lead content in soil. For accurate qualitative and quantitative analysis of heavy metals, the detection methodology based on the statistical algorithm and chemometrics method was proposed. The results showed that the system was sensitive, reliable and effective, which might hold great promise for its on-site analysis applications.

A pencil-lead bismuth film electrode and chemometric tools for simultaneous determination of heavy metals in propolis samples

A simultaneous determination of Zn, Cd, Pb and Cu in raw propolis samples, employing square wave anodic stripping voltammetry and chemometric tools, was developed. For this purpose, a pencil-lead bismuth film electrode was used as a working electrode. In order to optimize the parameters of square wave voltammetry a Box–Behnken design combined with desirability function was used. Different algorithms such Asymmetric Least Squares (AsLS) and Correlation Optimized Warping (COW) were employed in order to preprocess the raw data. Partial Least Squares (PLS) and Artificial Neuron Networks (ANN) were used to predict the concentration of the four metals in the samples. The method was tested successfully on raw propolis samples obtained from different localities of the Province of Buenos Aires, Argentina and the results were validated with recovery assays.

Dispersive liquid–liquid microextraction based on the solidification of floating organic drop followed by ICP-MS for the simultaneous determination of heavy metals in wastewaters

In the present work, a dispersive liquid–liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of Pb, Co, Cu, Ni, Zn. The influences of analytical parameters, including pH, extraction solvent volume, disperser solvent volume, concentration of chelating agent on the quantitative recoveries of Pb, Co, Cu, Ni, Zn were investigated. The effect of the interfering ions on the analytes recovery was also investigated. Under the optimized conditions, the limits of detection were 0.97–2.18ngL−1. The relative standard deviations (RSDs) were 2.62–4.51% (n=7, C=20ngL−1). The proposed method was successfully applied for the analysis of ultra trace metals in wastewater samples.

L-Cysteine Functionalized Silica Gel as an Efficient Adsorbent for the Determination of Heavy Metals in Foods by ICP-MS

A novel l-cysteine functionalized silica gel adsorbent (SG-Cys) was successfully synthesized and characterized by Fourier transform infrared (FTIR) spectra and elemental analysis. An efficient method for simultaneous determination of heavy metals [V (V), Cr (VI), Cu (II), As (V), Cd (II), and Pb (II)] was developed by inductively coupled plasma-mass spectrometry (ICP-MS) coupled with pre-concentration with the prepared SG-Cys adsorbent. The experimental parameters, including the solution pH, sample flow rate, eluent volume, eluent type, and concentration, have been systematically optimized to obtain higher enrichment factors of target ions. Under the optimum conditions, the enrichment factors of V (V), Cr (VI), Cu (II), As (V), Cd (II), and Pb (II) reached 123, 100, 86, 106, 97, and 94, respectively, and the detection limits were as low as 1.8–3.7 ng L−1. The proposed method has been applied to the determination of trace heavy metals in water, rice, wheat, corn, and tea samples, which exhibited a satisfactory recovery in the range of 90.6–106.0 %.

Simultaneous determination of heavy metals in biological samples by a multiple-template imprinting technique: an electrochemical study

In order to make people aware of the contamination of heavy metals in our daily life by inappropriate food intake, we have studied the contents of copper, cadmium, and lead in various components of our biota (soil, water, and plants, i.e. fruits and vegetables), collected from different areas (normal, industrial, coal-mine, river, and hill areas). For the accurate and rapid sensing of these metal ions, a multi-template imprinted nanowire modified electrochemical sensor was reported. The imprinted nanowire was synthesized using multiwalled carbon nanotubes as a core, on which a layer of conducting polyarginine is cast using an electro-polymerization technique. To study the total uptake of food-borne Cu(II), Cd(II), and Pb(II) ions in the human body, blood samples of six people were taken based on their different diets in their daily routine. Moreover, during the soil, water and plant analysis, it was observed that plants growing in a contaminated environment have a large accumulation of metal ions in their leaves and fruits. One more study was performed to explore ‘how much heavy metal we are taking in from our regular diet?’ and it was perceived that some of the food, which has lower concentrations of copper ions, can release a bigger amount of metal ions after digestion.

Ligandless-ultrasound-assisted emulsification microextraction followed by inductively coupled plasma-optical emission spectrometry for simultaneous determination of heavy metals in water samples

In this study, a simple and efficient method of ligandless-ultrasound-assisted emulsification microextraction (LL-USAEME) followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) has been developed for simultaneous extraction, preconcentration and determination of manganese, cadmium, cobalt and nickel in water samples. In the proposed approach, tetrachloroethylene was selected as extraction solvent. The effect of important experimental factors such as volume of extraction solvent, pH, sonication time, salt concentration, and temperature was investigated by using a fractional factorial design (25−1) to identify important factors and their interactions. In the next step, a Box-Behnken design (BBD) was applied for optimisation of significant factors. The obtained optimal conditions were: 30 µL for extraction solvent, 12 for pH, 5 min for sonication time, and 5% w/v for salt concentration. The limits of detections (LODs) for Cd(II), Co(II), Mn(II) and Ni(II) were 0.20, 0.13, 0.21 and 0.28 µg L−1, respectively. Relative standard deviations (RSD, C = 200.0 µg L−1, n = 9) were between 3.4–7.5% and the calibration graphs were linear in the range of 0.25 to 1000.0 µg L−1 for Mn, 0.5–1000.0 µg L−1 for Co and Ni and 1.0–250.0 µg L−1 for Cd. The determination coefficients (R 2) of the calibration curves for the analytes were in the range of 0.993 to 0.999. The proposed method was validated by using two certified reference materials, and also the method was applied successfully for the determination of heavy metals in different real water samples.

Simultaneous Determination of Zn(II), Cu(II), Cd(II) and Pb(II) in Soil Samples Employing an Array of Potentiometric Sensors and an Artificial Neural Network Model

AbstractA sensor array of 9 potentiometric PVC sensors has been employed for the simultaneous determination of heavy metals in soil. Sensors were firstly characterized in their response: Nernstian behavior, a concentration range from ca. 10−6 to 10−2 M and selectivity coefficients confirming that all sensors had cross‐response for the target ions. The mixed response system was modeled employing Artificial Neural Networks. The proposed tool was applied to the determination of Pb2+, Cd2+, Cu2+ and Zn2+ in soils at the mg kg−1 level with satisfactory performance. Results were compared and validated against AAS reference methodology, with correlations R2&gt;0.948 for the four heavy metals considered.

Ligandless-ultrasound-assisted emulsification-microextraction combined with inductively coupled plasma-optical emission spectrometry for simultaneous determination of heavy metals in water samples

In the present study, the simple and efficient method of ligandless-ultrasound-assisted emulsification-microextraction (LL-USAEME) has been developed for the simultaneous preconcentration and determination of chromium and zinc in water samples by inductively coupled plasma-optical emission spectrometry (ICP-OES). Tetrachloroethylene was selected as the extraction solvent. A fractional factorial design (25−1) and a Box–Behnken design (BBD) were used to identify and optimize the most important parameters that influence the ultrasound microextraction process. The optimum levels of the effective parameters were: 190 μL for volume of extraction solvent, 11.4 for pH, 15% (w/v) for the salt concentration and 5 min for sonication time. Under the optimum conditions, the relative standard deviations (RSDs, C = 100 μg L−1, n = 7) were 2.5% and 3.1% for Cr and Zn respectively. The calibration graphs were linear in the range of 0.5–1500 μg L−1 for both the metal ions with determination coefficients (R2) of 0.997. The limits of detection (LODs) for Cr and Zn were 0.20 and 0.28 μg L−1, respectively. The proposed method was successfully applied to the analysis of three real environmental water samples and satisfactory recoveries (90–109%) were achieved.

Correlation software algorithm for portable laser spectral analysis of heavy metal dopants

A novel correlation algorithm for laser spectral analyser (LSA) has been created for simultaneous determination of heavy metals' content in condensed matters, particularly in soils. This work is devoted to the design of a portable laser spectroscopy device for material contamination analysis using software with an original correlation algorithm. Detection sensitivity that can be achieved using this technique varies within 10–100 ppm. It has been demonstrated that acceptable results may be achieved during in-situ measurements. For a huge number of heavy metals, the limits of detection, which were determined experimentally with respect to unpolluted soil sample are lower. This system may provide fast in-situ analysis of heavy metal content and it uses optical fibre sensors.

Optimization of dispersive liquid–liquid microextraction coupled with inductively coupled plasma -optical emission spectrometry with the aid of experimental design for simultaneous determination of heavy metals in natural waters

In this study, dispersive liquid–liquid microextraction (DLLME) combined with inductively coupled plasma optical emission spectrometry (ICP-OES) was developed for simultaneous preconcentration and trace determination of chromium, copper, nickel and zinc in water samples. Sodium diethyldithiocarbamate (Na-DDTC), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. The effective parameters of DLLME such as volume of extraction and disperser solvents, pH, concentration of salt and concentration of the chelating agent were studied by a (2 f−1 ) fractional factorial design to identify the most important parameters and their interactions. The results showed that concentration of salt and volume of disperser solvent had no effect on the extraction efficiency. In the next step, central composite design was used to obtain optimum levels of effective parameters. The optimal conditions were: volume of extraction solvent, 113 μL; concentration of the chelating agent, 540 mg L −1; and pH, 6.70. The linear dynamic range for Cu, Ni and Zn was 1–1000 μg L −1 and for Cr was 1–750 μg L −1. The correlation coefficient ( R 2) was higher than 0.993. The limits of detection were 0.23–0.55 μg L −1. The relative standard deviations (RSDs, C = 200 μg L −1, n = 7) were in the range of 2.1–3.8%. The method was successfully applied to determination of Cr, Cu, Ni and Zn in the real water samples and satisfactory relative recoveries (90–99%) were achieved.

Simultaneous determination of copper, mercury and zinc in water with a tailored fluorescent bipyridine ligand entrapped in silica sol-gel

A novel fluorescent ligand, (4-[(E)-2-(4'-methyl-2,2'-bipyridin-4-yl)vinyl]phenol) (abbreviated BSOH), has been designed and prepared for simultaneous determination of heavy metals in water. Its photophysical and photochemical properties in the absence and in the presence of Cd(II), Cu(II), Hg(II), Ni(II) and Zn(II) were determined, and the respective complexation constants (7.4 × 10(3)-2.8 × 10(8) l mol(-1)) and stoichiometries were extracted thereof. The Stern-Volmer emission intensity and lifetime plots indicate an efficient static quenching of the indicator dye with the heavy metals. The BSOH fluorescent reagent has been successfully immobilised in a silica sol-gel matrix for automation of the analytical method, and the sensing phase demonstrated a reversible response to Cu(II), Hg(II) and Zn(II) but not to Cd(II) and Ni(II). Characterisation of the sensor showed that its response to those heavy metals is linear in the 2.5 to 50 μmol l(-1) range, with a response time (t (90)) on the order of 100 min, providing detection limits of 9.0 × 10(-7), 4.7 × 10(-7) and 2.9 × 10(-7) mol l (-1) for Zn(II), Cu(II) and Hg(II), respectively. Due to the stability of the immobilised ligand, which presented no leaching from the sol-gel matrix, the simultaneous determination of the three cations in water was feasible by employing multivariate calibration techniques coupled to fluorescence quenching measurements. The sensor was validated with recovery tests by addition of Cu(II) and Hg(II) ions to spring waters, providing results with standard errors lower than 4.1 μmol l (-1).