Ionic imprinted polymer based solid phase extraction for cadmium and lead pre-concentration/determination in seafood

An Environmental-friendly Procedure Based on Deep Eutectic Solvent for Extraction and Determination of Toxic Elements in Fish Species from Different Regions of Iraq

In this study, an eco-friendly procedure was established by vortex-assisted liquid-phase microextraction based on deep eutectic solvent (VA-LPME-DES) combined with graphite furnace atomic absorption spectroscopy (GFAAS). The performance of this method was demonstrated by the extraction and analysis of lead (Pb), cadmium (Cd), and mercury (Hg) in fish samples. The hydrophobic DES is considered as a green extractant (environmentally friendly and less toxic than common organic solvents) and is a suitable alternative to common toxic organic solvents and is made of l-menthol and ethylene glycol (EG) with a molar ratio of 1:1. Under optimized conditions, the method linearity was in the ranges of 0.15-150 µg kg-1 with the coefficient of determinations (r2) higher than 0.996. Accordingly, the detection limits for Pb, Cd, and Hg were 0.05, 0.05, and 0.10 µg kg-1, respectively. The analysis of fish samples showed that the concentration of toxic elements in fish caught from the Tigris and Euphrates Rivers is much higher than the concentration of these elements in locally farmed trout fish. Also, the analysis of fish-certified reference materials with presented procedure produced results that were in good agreement with the certified values. The results showed that VA-LPME-DES is a very cheap, fast, and environmental-friendly procedure for the analysis of toxic elements in different types of fish species.

Construction of 1, 10-phenanthroline functionalized magnetic starch as a lead (II) tagged surface imprinted biopolymer for highly selective targeting of toxic lead ions

In this research 1, 10 - phenanthroline functionalized CaFe₂O₄ - starch was employed as a magnetic ion-imprinted polymer (IIP) for highly selective targeting toxic Pb²⁺ ions from aqueous media. VSM analysis revealed that the sorbent has magnetic saturation of 10 emu g^-1 which is appropriate for magnetic separation. Moreover, TEM analysis confirmed that the adsorbent is composed of particles with a mean diameter of 10 nm. According to XPS analysis, lead coordination with phenanthroline is the main adsorption mechanism that is along with electrostatic interaction. A maximum adsorption capacity of 120 mg g^-1 was obtained within 10 min at a pH of 6 and an adsorbent dosage of 20 mg. Kinetic and isotherm studies showed that lead adsorption followed the pseudo-second-order and Freundlich models, respectively. The selectivity coefficient of Pb (II) relative to Cu(II), Co(II), Ni(II), Zn(II), Mn(II), and Cd(II) was 4.7, 14, 20, 36, 13 and 25, respectively. Moreover, the IIP represents the imprinting factor of 1.32. The sorbent showed good regeneration after five cycles of the sorption/desorption process with an efficiency of >93 %. Finally represented IIP was used for lead preconcentration from various matrices i.e., water, vegetable, and fish samples.

Development of a Sensitive Method for Cadmium Determination in Fish Tissue and Drinking Water Samples by FAAS Using SQT In Situ Atom Trapping

A sensitive and robust trap method was developed for the determination of cadmium (Cd) by using a slotted quartz tube. Using this method at a sample suction rate of 7.4 mL/min for 4.0 min collection, a 1467-fold increase in sensitivity was obtained compared to the flame atomic absorption spectrometry method. Under the optimized conditions, a limit of detection of 0.075 ng mL^-1 was obtained for the trap method. The interference effects of hydride-forming elements, transition metals, and some anions on the Cd signal were investigated. The developed method was evaluated by analyzing "Sewage Sludge-industrial origin (BCR no: 146R)", "NIST SRM 1640a Trace elements in natural water", and "DOLT: 5 Dogfish Liver". There was a good agreement between the certified and found values at the 95% confidence level. This method was applied successfully for the determination of Cd in drinking water and some fish tissue samples (liver, muscle, and gill) obtained from Muğla province.

From Classical to Advanced Use of Polymers in Food and Beverage Applications

Polymers are extensively used in food and beverage packaging to shield against contaminants and external damage due to their barrier properties, protecting the goods inside and reducing waste. However, current trends in polymers for food, water, and beverage applications are moving forward into the design and preparation of advanced polymers, which can act as active packaging, bearing active ingredients in their formulation, or controlling the head-space composition to extend the shelf-life of the goods inside. In addition, polymers can serve as sensory polymers to detect and indicate the presence of target species, including contaminants of food quality indicators, or even to remove or separate target species for later quantification. Polymers are nowadays essential materials for both food safety and the extension of food shelf-life, which are key goals of the food industry, and the irruption of smart materials is opening new opportunities for going even further in these goals. This review describes the state of the art following the last 10 years of research within the field of food and beverage polymer's applications, covering present applications, perspectives, and concerns related to waste generation and the circular economy.

[Recent advances in sample preparation technologies for analysis of harmful substances in aquatic products]

Aquatic products, which are among the most important sources of animal protein, contain proteins, vitamins, and a variety of trace elements, thus occupying an indispensable part of a reasonable diet. China is the largest consumer market of aquatic products in the world. The quality and safety of aquatic products are closely related not only to the healthy development of the aquaculture industry, but also to people's health. However, the presence of harmful substances has a bearing on the quality and safety of aquatic products in the overall process, including breeding, processing, storage, and transportation. These harmful substances are enriched in aquatic products and are transferred to humans via the food chain. Accurate determination of such harmful substances in aquatic product samples is imperative because of their complex matrices and extremely low concentrations. Many efficient sample preparation techniques such as liquid-liquid extraction, solid-phase extraction, and QuEChERS (quick, easy, cheap, effective, rugged, and safe method) with different configurations have been developed and widely employed for preconcentration in different matrices of aquatic products. Meanwhile, solid-phase microextraction has been demonstrated to be advantageous for some volatile and ultra-trace harmful substances. Suitable sample preparation techniques are important for effectively removing matrix interferences as well as for improving the sensitivity and accuracy of the method. It is important to develop appropriate sample preparation techniques for different target compounds in aquatic products. The harmful substances in aquatic products can be segregated into three categories according to their sources: (1) environmental pollutants in aquatic products; (2) substances acquired during aquaculture, transportation, and processing; (3) biotoxins in aquatic products. This article reviews the progress in sample pretreatment techniques for three harmful substances in aquatic products over the past decade. Various sample pretreatment techniques have been summarized and described, including liquid-liquid extraction, solid-phase extraction, solid-phase microextraction, QuEChERS, and magnetic solid-phase extraction. In addition, the merits and demerits of these techniques and future research directions are discussed. Finally, we reviewed the progress in functionalized materials for the preparation of aquatic product samples. With the increasing demand for aquatic products, quick, sensitive, and practical detection methods, such as surface-enhanced Raman scattering (SERS) are gaining importance. SERS has great potential for fast and accurate on-site detection of harmful substances in aquatic products. Several nondestructive sample pretreatment techniques have also been developed for harmful substances in aquatic products. The application and development of these techniques will guarantee the safety of aquatic products. Moreover, in vivo solid-phase microextraction is a potential method for aquatic product analysis. This technique integrates sampling, extraction, and enrichment into a single step, thus significantly reducing the processing time, labor, and cost. Overall, with the development and application of sophisticated materials and techniques, we can expect theoretical and practical advances in aquatic product analysis.

A Critical Review on the Synthesis and Application of Ion-Imprinted Polymers for Selective Preconcentration, Speciation, Removal and Determination of Trace and Essential Metals from Different Matrices

The presence of toxic trace metals and high concentrations of essential elements in the environment presents a serious threat to living organism. Various methods have been used for the detection, preconcentration and remediation of these metals from biological, environmental and food matrices. Owing to the complexicity of samples, methods with high selectivity have been used for detection, preconcentration and remediation of these trace metals. These methods are achieved by the use of ion-imprinted polymers (IIPs) due to their impressive properties such as selectivity, high extraction efficiency, speciation capability and reusability. Because of the increase of toxic trace and essential metals in the environment, IIPs have attracted great use in analytical chemistry. This review, provide a brief background on IIPs and polymerization method that are used for their preparation. Recent applications of IIPs as adsorbents for preconcentration, removal, speciation and electrochemical detection of trace and essential metal is also discussed.

Sensitive colorimetric detection of Pb2+ by geometric field amplification and surface plasmon resonance visualization

Pb²⁺ is one of the major environmental pollutants, which can be visually detected by surface plasmon resonance of nanoparticles. Paper based analytical device, as a newly developed microfluidic detection platform, is featured in cost-effective and suitable for on-site analysis. In this paper, a sensitive and portable detection method for Pb²⁺ was proposed, in which Pb²⁺ was electrokinetically stacked on the paper fluidic channel by geometric field amplification effect and visualized online by glutathione-modified silver nanoparticles. Colorimetric quantification of the visualized stacking band was conducted by smart phone camera. To avoid unfavorable influence from pH change on the surface plasmon resonance visualization, field amplification effect was introduced by geometric design of the paper fluidic channel. The enriched Pb²⁺ was clearly visible on the paper substrate, and the stacking band intensity was about four orders of magnitude enhanced, comparing to the intensity without stacking. A linear response to Pb²⁺ was observed in the range of 0.3-7.0 μM (R² = 0.997) with a limit of detection of 86 nM and a limit of quantity of 0.28 μM. The established method was used in the detection of Pb²⁺ from river and lake water samples, and the results were confirmed by atomic absorption spectroscopy method.

Ensuring high selectivity for preconcentration and detection of ultra-trace cadmium using a phage-functionalized metal–organic framework

A phage functionalized metal–organic framework for selective preconcentration and detection of trace cadmium.

Novel Imprinted Polymer for the Preconcentration of Cadmium with Determination by Inductively Coupled Plasma Mass Spectrometry

A novel Cd(II)-imprinted polymer was prepared with chemical immobilization approach by using N-methacryloyl-L-histidine as a vinylated chelating agent for on-line solid phase extraction of Cd(II) for determination by inductively coupled plasma mass spectrometry. Cd(II)-monomer complex was synthesized and copolymerized via bulk polymerization method in the presence of ethyleneglycoldimethacrylate cross-linker. The resulting polymer was leached with 1.0 mol L^-1 HNO₃ to generate the cavities in the polymer for Cd(II) ions. The experimental conditions, including load pH, solution flow rate, and eluent concentration for effective sorption of Cd(II) were optimized using a minicolumn of the imprinted polymer. A volume of 5.0 mL sample 5 μg L^-1 Cd(II) solution at pH 6.5 was loaded onto the column at 2.0 mL min^-1 by using a sequential injection system (FIALab 3200) followed by elution with 1.0 mL of 0.75 mol L^-1 HNO₃. The relative selectivity coefficients of the imprinted polymer for Cd(II) were 38.5, 3.5, 3.0, 2.5 and 6.0 in the presence of Cu(II), Ni(II), Zn(II), Co(II) and Pb(II), respectively. Computational calculations revealed that the selectivity of the imprinted polymer was mediated by the stability of Cd(II)-N-methacryloyl-L-histidine complex which was far more stable than those of commonly used monomers, such as 4-vinyl pyridine, methacrylic acid and vinylimidazole. The detection limit (3s) and relative standard deviation (%) were found to be 0.004 μg L^-1 and 3.2%, respectively. The method was validated by analysis of seawater certified reference material (CASS-4) and successfully applied to the determination of Cd(II) in coastal seawater and estuarine water samples.

Ion Imprinted Polymer for Preconcentration and Determination of Ultra-Trace Cadmium, Employing Flow Injection Analysis with Thermo Spray Flame Furnace Atomic Absorption Spectrometry

This work proposes a preconcentration method using an ion imprinted polymer (IIP) for determination of cadmium, in several samples, employing a mini-column filled with the polymer coupled into a flow injection analysis system with detection by thermospray flame furnace atomic absorption spectrometry (FIA-TS-FF-AAS). The polymer was synthesized via bulk using methacrylic acid and vinylimidazole as a functional monomer. For the FIA system initial assessment, the variables: pH, eluent concentration and buffer concentration were studied, employing a 23 full factorial design. To obtain the optimum values for each significant variable, a Doehlert matrix was employed. After the optimization conditions as: pH 5.8, eluent (HNO3) concentration of 0.48 mol L^-1 and buffer concentration of 0.01 mol L^-1, were adopted. The proposed method showed a linear response in the range of 0.081-10.0 μg L^-1, limits detection and quantification of 0.024 and 0.081 μg L^-1, respectively; preconcentration factor of 165, consumptive index of 0.06 mL, concentration efficiency 132 min^-1, and frequency of readings equal to 26 readings h^-1 The accuracy was checked by analysis of certified reference materials for trace metals and recovery tests. The obtained results were in agreement with 95% confidence level (t-test). The method was adequate to apply in samples of: jewelry (earrings) (2.38 ± 0.28 μg kg^-1), black tea (1.09 ± 0.15 μg kg^-1), green tea (3.85 ± 0.13 μg kg^-1), cigarette tobacco (38.27 ± 0.22 μg kg^-1), and hair (0.35 ± 0.02 μg kg^-1).

Synthesis of multi-ion imprinted polymers based on dithizone chelation for simultaneous removal of Hg2+, Cd2+, Ni2+ and Cu2+ from aqueous solutions

A multi-ion imprinted polymer strategy based on dithizone chelation for simultaneous removal of multiple ions in aqueous solution.

Highly selective monitoring of metals by using ion-imprinted polymers

Ion imprinting technology is one of the most promising tools in separation and purification sciences because of its high selectivity, good stability, simplicity and low cost. It has been mainly used for selective removal, preconcentration, sensing and few miscellaneous fields. In this review article, recent methodologies in the synthesis of IIPs have been discussed. For several applications, different parameters of IIP including complexing and leaching agent, pH, relative selectivity coefficient, detection limit and adsorption capacity have been evaluated and an attempt has been made to generalize. Biomedical applications mostly include selective removal of toxic metals from human blood plasma and urine samples. Wastewater treatment involves selective removal of highly toxic metal ions like Hg(II), Pb(II), Cd(II), As(V), etc. Preconcentration covers recovery of economically important metal ions such as gold, silver, platinum and palladium. It also includes selective preconcentration of lanthanides and actinides. In sensing, various IIP-based sensors have been fabricated for detection of toxic metal ions. This review article includes almost all metal ions based on the ion-imprinted polymer. At the end, the future outlook section presents the discussion on the advancement, corresponding merits and the need of continued research in few specific areas. Graphical Abstract IIPs for the selective monitoring of metals.

Double preconcentration of trace amounts of cadmium in nail samples and measurement by differential pulse voltammetry

Cadion was coated on carbon powder and used as a solid phase for selective extraction and preconcentration of cadmium ions. Complexed cadmium ions were eluted from solid phase by 5 mL, nitric acid (2.0 M) with the flow rate of 2 mL min(-1).The resulted solution was used for accumulation of the cadmium metal at the surface of the carbon paste electrode at -1.3 V reduction potential. Finally, cadmium was reoxidized and the differential pulse voltammogram recorded at the potential range of -0.55 to -0.2 V. Calibration graph was plotted in the concentration range of 0.5-50 μg L(-1) of cadmium. Detection limit 0.06 μg L(-1) was calculated based on the 3 Sb/m. The RSD was 9.13 % (n = 4) for cadmium concentration of 10 μg L(-1) with preconcentration factor of 100. Method was successfully used for the determination of cadmium in finger nail samples and after spiking the samples, the recoveries were evaluated >96 %.