Application of multiwalled carbon nanotubes modified by diphenylcarbazide for selective solid phase extraction of ultra traces Cd(II) in water samples and food products

Review on heavy metal contaminants in freshwater fish in South India: current situation and future perspective

The primary natural resource we use in our daily lives for a variety of activities is freshwater for drinking and various developmental goals. Furthermore, the pace of human population increase worldwide is rising rapidly and has a great impact on the Earth's natural resources. Natural water quality has diminished owing to various anthropogenic activities. Water is crucial to the life cycle. On the other hand, chemical and agricultural industries pollute heavy metals. Acute and chronic diseases caused by heavy metals, such as slow metabolism and damage to the gills and epithelial layer of fish species, are divided into two categories. Pollutants can also harm liver tissues and result in ulceration as well as diseases such as fin rot, tail rot, and gill disease. The most prevalent heavy metals are As, Cr, Pb, and Hg, which are systemic toxicants that affect human health. These metals are categorized as carcinogens by the US Environmental Protection Agency and the worldwide agency for cancer research because they cause organ damage even at low exposure levels. The focus of the current study is to review various freshwater sources of heavy metal pollution.

Landscape composition and inorganic contaminants in water and muscle tissue of Plagioscion squamosissimus in the Araguari River (Amazon, Brazil)

Amazonian aquatic environments are seriously impacted by dam-building and deforestation, among other threats. Therefore, the present study aimed to examine water quality in the middle and lower course of the Araguari River with respect to the composition of vegetative cover and the concentration of As, Cd and Hg in order to determine risks to the preservation of biota and risks to human health from consumption of P. squamosissimus contaminated with these inorganic elements. To accomplish this, water samples and fish specimens were collected in the middle and lower Araguari River in 2019. The concentration of inorganic contaminants was analyzed by atomic absorption spectrophotometry. These stretches of the Araguari River presented higher proportions of forest fragments and evident expansion of buffalo pastures. According to Brazilian legislation, the concentrations of Cd and Hg in the water samples represented risk quotient values > 1, indicating risk to the preservation of aquatic biota. In particular, the concentrations of Cd in the muscle tissue of P. squamosissimus in the lower Araguari River also indicated risks to human health. The bioaccumulation factor indicated that Hg is bioavailable in the water. It can be concluded that water imbalances in the middle and lower Araguari River compromise the health of both aquatic and human life.

Inhibition of CRISPR-Cas12a trans-cleavage by lead (II)-induced G-quadruplex and its analytical application

In this work, the inhibition of clustered regularly interspaced short palindromic repeats (CRISPR) - CRISPR associated protein (Cas) trans-cleavage by Pb²⁺-induced G-quadruplex has been firstly explored to detect Pb²⁺ in tea beverage and milk. In absence of Pb²⁺, the Na⁺-induced G-quadruplex can be cleaved by CRISPR-Cas12a. In contrast, Pb²⁺ can competitively combine with G-quadruplex, resulting in its conformational changes and resistance to trans-cleavage of CRISPR-Cas12a. Therefore, the fluorescence resonance energy transfer can happen. Pb²⁺ can be detected in a linear range from 100 nM to 5 µM with a lowest detection limit of 2.6 nM and a relative standard deviation of 4.32%. In summary, this work not only provides a new method for Pb²⁺ detection based on its induced G-quadruplex inhibition on CRISPR-Cas12a trans-cleavage, but also broadens the application of CRISPR-Cas system for heavy metal analysis in the field of food safety.

Health risk assessment and heavy metal accumulation in fish species (Clarias gariepinus and Sarotherodon melanotheron) from industrially polluted Ogun and Eleyele Rivers, Nigeria

•

Concentration of Arsenic and Cadmium in the fish tissues exceed the limits set by the European Union.

•

THQ values indicated likely adverse effects during a person’s lifetime with continuous exposure to Arsenic and Cadmium.

•

As, Cd, and Nickel may pose cancer risk to consumer of fish from the two rivers over longtime exposure.

•

Cancer risk due to long time consumption of fish from the rivers can be a major concern.

Ogun and Eleyele Rivers are in the Western part of Nigeria with a potential risk of heavy metal pollution because of many industrial wastes channeling through their courses. Therefore, in this study, the concentration of heavy metals and the possible human health risk of consuming Clarias gariepinus and Sarotherodon melanotheron collected from industrially polluted Ogun and Eleyele Rivers in Nigeria were evaluated.

The concentration of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), manganese (Mn), nickel (Ni), and lead (Pb) in tissues (gill, muscle, and liver) of fish was measured using Atomic Absorption Spectroscopy (AAS) and compared with the maximum permissible. The Estimated Daily Intake (EDI), Targeted Hazard Quotient (THQ), and Carcinogenic Risk (CR) of the metals were estimated for the determination of human health risk. Probabilistic predictions of the health risk were performed with Oracle Crystal Ball software.

Results of this study showed that the dry weight concentrations of the metals in the gills, liver, and muscle of the two fish species from the two sites were well below the permissible limits set by the joint FAO/WHO Expert Committee. Only the EDI for arsenic in gills of C. gariepinus obtained from the Ogun River exceeded the set limit. The THQ was >1 for As in the gills and liver of C. gariepinus and S. melanotheron obtained from the Ogun river suggesting non-carcinogenic risk to the consumers. The carcinogenic risk above 10⁻⁶ obtained for As, Cd, and Ni in the tissues of the two fish species suggested cancer risk to the consumers of fish from the two rivers. Consequent to our observation, consumption of fish from the study site presents some public health concerns. Therefore, this study advises routine heavy metal monitoring of fish along these rivers to implement regulatory standards by the government environmental health management agencies.

Carboxyl-functionalized hollow polymer microspheres for detection of trace metal elements in complex food matrixes by ICP-MS assisted with solid-phase extraction

In this work, carboxyl-functionalized hollow polymer microspheres (CHPMs) was successfully fabricated using poly (styrene-itaconic anhydride) particles as the core template and itaconic anhydride and trans-anethole cross-linked with divinylbenzene as the shell. The desirable microspheres and hollow structure of CHPMs were demonstrated by scanning and transmission electron microscopies, respectively. The characterized CHPMs as an adsorbent was packed into a solid phase extraction column to simultaneously detect the V(V), Cr(III), Cu(II), Cd(II), and Pb(II) in digested food samples by inductively coupled plasma-mass spectrometry (ICP-MS). A series of experimental parameters of solid-phase extraction (SPE) were investigated through vast experiments to improve sensitivity of the proposed method in metal ions detection. The detection limits of the method reached 0.8-3.2 ng L^-1 for the target elements, and the relative standard deviations (RSDs) ranging from 1.2% to 3.5% were obtained from eleven parallel experiments using a 1.0 μg L^-1 sample solution. The stability allowed the material to withstand more than 15 cycling while the recoveries remained above 88%. In food samples, the detection limits were at 0.20-0.80 μg kg^-1, and satisfactory recoveries of 85-104% were obtained in spike tests of laver, fish as well as chicken.

Dopamine-modified magnetic graphene oxide as a recoverable sorbent for the preconcentration of metal ions by an effervescence-assisted dispersive micro solid-phase extraction procedure

Nanomagnetic graphene oxide modified with dopamine (GO-Fe3O4-DA) was synthesized via a very simple procedure. Using GO-Fe3O4-DA as the new adsorbent, the effervescence-assisted dispersive micro solid-phase extraction procedure was exploited for the preconcentrative extraction of Cu(ii), Pb(ii) and Ni(ii) ions. Structural characteristics of the adsorbent were studied via FT-IR, FE-SEM, EDX and XRD analyses. The rapid dispersion and high adsorption capability of GO-Fe3O4-DA, along with the rapid separation of the adsorbent from the aqueous phase by a magnet, led to a decrease in the extraction time of the target metal ions. In effect, high extraction percentages were attained in a very short time period. In this work, the relative standard deviations (RSD; n = 3) calculated for the proposed method were 1.09, 1.25 and 1.03% for the Pb(ii), Cu(ii) and Ni(ii) ions, respectively, the calibration curve was dynamically linear in the range of 0.25 to 50 μg L-1, and the limits of detection were obtained as 0.5, 0.1, and 0.7 μg L-1. The procedure was also implemented on real sausage (herbal and meaty) samples and a water sample, vouchsafing the success of the proposed method in tackling real samples with a complicated matrix.

Electrocatalytic determination of Cd2+ and Pb2+ using an l-cysteine tungstophosphate self-assembled monolayer on a polycrystalline gold electrode

Constructing a sensitive electrochemical sensor based on (Cys)PW for Cd²⁺ and Pb²⁺ detection at the nanomolar level with remarkable selectivity.

Adsorptive Removal of Hexavalent Chromium by Diphenylcarbazide-Grafted Macadamia Nutshell Powder

Macadamia nutshell powder oxidized by hydrogen peroxide solutions (MHP) was functionalized by immobilizing 1,5′-diphenylcarbazide (DPC) on its surface. The effectiveness of grafting was confirmed by the Fourier transform infrared spectrum due to the presence of NH and C=C stretches at 3361, 1591, and 1486 cm⁻¹, respectively, on the grafted material which were absent in the nongrafted material. Thermogravimetric analysis revealed that the presence of DPC on the surface of Macadamia shells lowered the thermal stability from 300°C to about 180°C owing to the volatile nature of DPC. Surface roughness as a result of grafting was appreciated on the scanning electron microscopy images. Parameters influencing the adsorptive removal of Cr(VI) were examined and found to be optimal at pH 2, 120 min, 150 mg/L, and 2.5 g/L. Grafting MHP with DPC leads to an increase in the Langmuir monolayer capacity from 37.74 to 72.12 mg/g. Grafting MHP with DPC produced adsorbent with improved removal efficiency for Cr(VI).

Composites Based on Conducting Polymers and Carbon Nanomaterials for Heavy Metal Ion Sensing (Review)

Current review signifies recent trends and challenges in the development of electrochemical sensors based on organic conducting polymers (OCPs), carbon nanotubes (CNTs) and their composites for the determination of trace heavy metal ions in water are reviewed. OCPs and CNTs have some suitable properties, such as good electrical, mechanical, chemical and structural properties as well as environmental stability, etc. However, some of these materials still have significant limitations toward selective and sensitive detection of trace heavy metal ions. To overcome the limitations of these individual materials, OCPs/CNTs composites were developed. Application of OCPs/CNTs composite and their novel properties for the adsorption and detection of heavy metal ions outlined and discussed in this review.

Solid-phase extraction of multi-class pharmaceuticals from environmental water samples onto modified multi-walled carbon nanotubes followed by LC-MS/MS

In this paper, pristine and chemically treated multi-walled carbon nanotubes (MWCNTs) were employed as solid-phase extraction sorbents for the isolation and enrichment of multi-class pharmaceuticals from the surface water and groundwater, prior to liquid chromatography-tandem mass spectrometry analysis. Thirteen pharmaceuticals that belong to different therapeutical classes (erythromycin, azithromycin, sulfamethoxazole, diazepam, lorazepam, carbamazepine, metoprolol, bisoprolol, enalapril, cilazapril, simvastatin, clopidogrel, diclofenac) and two metabolites of metamizole (4-acetylaminoantipyrine and 4-formylaminoantipyrine) were selected for this study. The influence of chemical treatment on MWCNT surface characteristics and extraction efficiency was studied, and it was shown that HCl treatment of MWCNT leads to a decrease in the amount of surface oxygen groups and at the same time favorably affects the efficiency toward extraction of selected pharmaceuticals. After the optimization of the SPE procedure, the following conditions were chosen: 50 mg of HCl-treated MCWNT as a sorbent, 100 mL of water sample at pH 6, and 15 mL of the methanol-dichloromethane mixture (1:1, v/v) as eluent. Under optimal conditions, high recoveries (79-119%), as well as low detection (0.2 to 103 ng L^-1) and quantitation (0.5-345 ng L^-1) limits, were obtained. The optimized method was applied to the analysis of five surface water and two groundwater samples, and three pharmaceuticals were detected, the antiepileptic drug carbamazepine and two metabolites of antipyretic metamizole.

Functionalization of magnetic hollow porous oval shape NiFe2O4 as a highly selective sorbent for the simultaneous determination of five heavy metals in real samples

In this study, a functionalized magnetic hollow porous oval-shape NiFe2O4 (MHPO-NiFe2O4) was designed by a facile synthesis procedure, and employed as magnetic solid phase extraction (MSPE) material to extract several heavy metal ions. As-prepared MHPO-NiFe2O4 exhibited superior adsorption capacities of 20.17, 16.64, 16.82, 9.69 and 16.58mgg-1, for Cu(II), Cd(II), Cr(III), Co(II) and Zn(II), and was then used to detect these heavy metals elements in real samples by combining with inductively coupled plasma optical emission spectroscopy (ICP-OES). The possible mechanism of the enrichment of heavy metals ions on MHPO-NiFe2O4 was proposed, which involved the dominant adsorption and desorption. The detection limits were as low as 0.015, 0.13, 0.062, 0.035 and 0.46μgL-1 for Cu(II), Cd(II), Cr(III), Co(II) and Zn(II), respectively. A good repeatability was obtained with the relative standard deviation (RSD) of 3.87%. Moreover, the method was successfully utilized for the analysis of five heavy metals in real samples (cabbage, lettuce, apple, seawater), with satisfactory recoveries in the range of 92-108%.

Chromium Speciation in Wastewater and Sewage by Solid-Phase Extraction Using a New Diphenylcarbazone-Incorporated Resin

A new procedure for the determination of chromium species in polluted environmental samples by flame atomic absorption spectrometry was developed in this work. A new material containing 1,5-diphenylcarbazone included in a polymeric matrix was prepared and employed as a solid-phase extraction material for selective separation of Cr(III) ions under dynamic conditions. Chromium(III) ions were retained on this sorbent with high efficiency and repeatability (95 %, RSD = 1 %) from solutions with pH 9.0. The quantitative recovery of analyte was obtained with 0.1 mol L-1 EDTA. The concentration of Cr(VI) ions was calculated from the difference between the concentration of total chromium and Cr(III) ions. The prepared sorbent exhibits good chemical and mechanical stability, sorption capacity and selectivity towards Cr(III) ions in the presence of Cu(II), Ni(II), Mn(II) and Ca(II) ions. The accuracy of the separation method was proved by analysis of reference material of wastewater RES 10.2. The developed procedure was applied for chromium speciation analysis in municipal sewage samples.

A new magnetic tailor made polymer for separation and trace determination of cadmium ions by flame atomic absorption spectrophotometry

Magnetic ion imprinted polymers have been prepared and applied for the selective extraction and trace monitoring of cadmium ions in food samples.

Use of Modified γ-Alumina Nanoparticles for the Extraction and Preconcentration of Trace Amounts of Cadmium Ions

We used γ-Al2O3 nanoparticles coated with sodium dodecyl sulfate–4-(2-pyridylazo)resorcinol (SDS–PAR) as an innovative sorbent for the extraction and preconcentration of trace amounts of cadmium cations. The properties of the prepared sorbent were examined by scanning electron microscopy. The effects of different parameters towards the separation and preconcentration of trace amounts of cadmium ions, such as the quantity of sorbent, the pH value, and choice of solvent for recovery of the sorbent, were investigated. Under optimum operating conditions, a cadmium ion enrichment factor of 20 was obtained using 10.0 mL of sample. The detection limit of this method for CdII cations was 0.2 ng mL–1 (n = 7) within a linear range of 0.6–340 ng mL–1 and a relative standard deviation of 1.8 % (n = 10). The method was effectively applied to the analysis of cadmium ions in food and herbal and water samples.

Determination of some metal ions in various meat and baby food samples by atomic spectrometry

In this paper, we report a simple and rapid solid phase extraction system for the separation/preconcentration and determination of Cd(II), Co(II), Cu(II), Fe(III), Cr(III), Pb(II), and Zn(II) ions by flame atomic absorption spectrometry (FAAS). This method is based upon the retention of metal ions on a column packed with poly[N-(3-methyl-1H-indole-1-yl)]-2-methacrylamide-co-2-acrylamido-2-methyl-1-propane sulphonic acid-co divinylbenzene] (MMAD) resin as a solid-phase extraction (SPE) sorbent at pH 8. At the optimized conditions, the limits of detection (3 s/b) between 0.12 and 1.6 μg L(-1), preconcentration factor of 100, and the relative standard deviation of ⩽1.8% were achieved (n=10). The accuracy of the method was verified by analyzing certified reference materials (CRMs) and performing recovery experiments. The developed method was successfully applied to the various natural water, meat products and baby food samples. The recoveries of analyte ions were found in added real samples and CRMs from 95% to 102%.

Recent advances in applications of nanomaterials for sample preparation

Sample preparation is a key step for qualitative and quantitative analysis of trace analytes in complicated matrix. Along with the rapid development of nanotechnology in material science, numerous nanomaterials have been developed with particularly useful applications in analytical chemistry. Benefitting from their high specific areas, increased surface activities, and unprecedented physical/chemical properties, the potentials of nanomaterials for rapid and efficient sample preparation have been exploited extensively. In this review, recent progress of novel nanomaterials applied in sample preparation has been summarized and discussed. Both nanoparticles and nanoporous materials are evaluated for their unusual performance in sample preparation. Various compositions and functionalizations extended the applications of nanomaterials in sample preparations, and distinct size and shape selectivity was generated from the diversified pore structures of nanoporous materials. Such great variety make nanomaterials a kind of versatile tools in sample preparation for almost all categories of analytes.

Trace monitoring of silver ions in food and water samples by flame atomic absorption spectrophotometry after preconcentration with solvent-assisted dispersive solid phase extraction

In this research, a new sample treatment technique termed solvent-assisted dispersive solid phase extraction (SADSPE) was developed. The new method was based on the dispersion of the sorbent into the sample to maximize the contact surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by injecting a mixture solution of the sorbent and disperser solvent into the aqueous sample. Thereby, a cloudy solution formed. The cloudy solution resulted from the dispersion of the fine particles of the sorbent in the bulk aqueous sample. After extraction, the cloudy solution was centrifuged and the enriched analytes in the sediment phase dissolved in ethanol and determined by FAAS. Under the optimized conditions, the detection limit for silver ions was 0.8 μg L(-1). The relative standard deviations for six separate extraction experiments for determination of 5 and 200 μg L(-1) of silver ions was 3.4 and 3.1 %. The preconcentration factor was found to be 61.7. SADSPE was successfully applied for trace determination of silver ions in water and food samples.

Efficacy of dihydroxy-mercaptopyrimidine functionalized polymeric resin for the trace determination of Cd by SPE coupled flame atomic absorption spectrometry

The efficacy and applicability of a cadmium extractor prepared by functionalizing polystyrene resin with 2-thiobarbituric acid is studied. This is the first time that 2-thiobarbituric acid is reported in solid phase extraction as a chelating resin.