Conductive polyaniline-graphene oxide sorbent for electrochemically assisted solid-phase extraction of lead ions in aqueous food samples

Sensing lead ions in water: a comprehensive review on strategies and sensor materials

It is well-known fact that elevated lead ions (Pb2+), the third most toxic among heavy metal ions in aqueous systems, pose a threat to human health and aquatic ecosystems when they exceed permissible limits. Pb2+ is commonly found in industrial waste and fertilizers, contaminating water sources and subsequently entering the human body, causing various adverse health conditions. Unlike being expelled, Pb2+ accumulates within the body, posing potential health risks. The harmful impact of presence of Pb2+ in water have prompted researchers to diligently work toward maintaining water quality. Recognizing the importance of Pb2+, this review article makes a sincere and effective effort to address the issues associated with Pb2+. This overview article gives insights into various sensing approaches to detect Pb2+ in water using different sensing materials, including 2-dimensional materials, thiols, quantum dots, and polymers. Herein, different sensing approaches such as electrochemical, optical, field effect transistor-based, micro-electromechanical system-based, and chemi resistive are thoroughly explained. Field effect transistor-based and chemiresistive work on similar principles and are compared on the basis of their fabrication processes and sensing capabilities. In conclusion, future directions for chemiresistive sensors in Pb2+ detection are proposed, emphasizing their simplicity, portability, straightforward functionality, and ease of fabrication. Notably, it sheds light on various thiol and ligand compounds and coupling strategies utilized in Pb2+ detection. This comprehensive study is expected to benefit individuals engaged in Pb2+ detection.

Comparison of ZrO2 Particles and Polyaniline as Additives in Polystyrene-Based Sorbents for the Micro-Solid Phase Extraction of Psychoactive Drugs from Biofluids

The intensive development of extraction methods based on μ-SPE extraction contributes to the increased interest in the synthesis of new sorption materials. This work presents the characterization of polystyrene fibers and polystyrene fibers blended with ZrO2 particles or polyaniline obtained by electrospinning and their use in the extraction of selected psychoactive drugs from biological samples. The characteristic of produced fibers is made by performing SEM images, measuring average fiber diameter, and examining their sorption abilities. Among the fibers based on pure polystyrene, tested in the first stage, the best sorption properties are demonstrated for the fibers obtained from a polystyrene solution in DMF with a concentration of 17.5 wt%. In the next stage, this material was modified with synthesized ZrO2 particles and polyaniline. Among the tested materials, the sorbent based on polystyrene with polyaniline shows the best sorption properties of the tested substances. The use of this material in the μ-SPE in a needle enables the extraction of selected compounds from aqueous and biological samples such as urine and human plasma.

Determination of lead in Gentiana rigescens and evaluation of the effect of lead exposure on the liver protection of the natural medicine

In this work, ultrasound-assisted rapidly synergistic cloud point extraction (UARS-CPE) and inductively coupled plasma optical emission spectrometry (ICP-OES) were combined to determine trace Pb in Gentiana rigescens Franch. ex Hemsl. (G. rigescens) samples. Under the optimal conditions, the enhancement factor (EF), limit of detection (LOD), limit of quantitation (LOQ) and precision were 33, 0.11 μg L^-1, 0.37 μg L^-1 and 1.3%, respectively. This method was applied to the analysis of G. rigescens samples, and the outcomes were in good agreement with the results determined by inductively coupled plasma mass spectrometry (ICP-MS). A mice model of immune liver injury induced by concanavalin A (ConA) was established, and the liver protection of G. rigescens and gentiopicroside (GPS) on it and the effects of various dosages of Pb exposure on its liver protection were studied. Pb at a dosage of 5 mg kg^-1 had little effect on the liver protection of G. rigescens and GPS, while 25, 125 mg kg^-1 dosages of Pb could significantly attenuate the liver protection of both. In addition, it aggravated the necrosis of hepatocytes and inflammatory cell infiltration, and these effects were dose-dependent.

Emerging Applications of Versatile Polyaniline-Based Polymers in the Food Industry

Intrinsically conducting polymers (ICPs) have been widely studied in various applications, such as sensors, tissue engineering, drug delivery, and semiconductors. Specifically, polyaniline (PANI) stands out in food industry applications due to its advantageous reversible redox properties, electrical conductivity, and simple modification. The rising concerns about food safety and security have encouraged the development of PANI as an antioxidant, antimicrobial agent, food freshness indicator, and electronic nose. At the same time, it plays an important role in food safety control to ensure the quality of food. This study reviews the emerging applications of PANI in the food industry. It has been found that the versatile applications of PANI allow the advancement of modern active and intelligent food packaging and better food quality monitoring systems.

Ultrasound-assisted dispersive magnetic solid-phase extraction of cadmium, lead and copper ions from water and fruit juice samples using DABCO-based poly (ionic liquid) functionalized magnetic nanoparticles

A poly (ionic liquid) (PIL) functionalized magnetic nanoparticles methodology was developed and utilized as an efficient adsorbent for the simultaneous extraction of cadmium, lead, and copper ions from water and fruit juice samples. The novel adsorbent was fabricated by grafting DABCO-based PIL onto silica-coated Fe₃O₄ nanoparticles via copper (0)-mediated reversible-deactivation radical polymerization. Different techniques properly characterized the developed nanoparticles. The central composite design was used to analyze the simultaneous effects of various parameters on the extraction efficiency. The detection limits for water samples ranged between 3.2 and 9.2 ng.L^-1, and fruit juice samples varied from 0.0103 to 0.1082 μg.kg^-1. The recovery ranged from 94.1 to 101.3% and 93.6 to 105.1% for water and fruit juice samples, respectively. The relive measurement uncertainty ranged from 7.7 to 13.6%. The proposed method is rapid, sensitive, environmentally friendly, and useful for monitoring the residues of heavy metal ions in water and fruit juice samples.

Conductive Polymer-Based Nanocomposites as Powerful Sorbents: Design, Preparation and Extraction Applications

Conductive polymers as composite materials have been attracted tremendous attention due to their versatile and excellent features such as tunable conductivity, facile synthesis and fabrication, high chemical and thermal stability etc. These characteristics make them versatile and let them being used in numerous fields including microelectronics, optics and biosensors. Throughout the mentioned fields, conductive polymers particularly perform as effective sorbents. Although tremendous efforts have been put into this topic, to the best of our knowledge, a comprehensive up-to-date review on the applications of conductive polymers as efficient sorbents has not been reported. The main objective of this paper is to make a significant contribution to the recent literature toward the synthesis and extraction applications of conductive polymers as efficient sorbents.

Simultaneous detection of eight phenols in food contact materials after electrochemical assistance solid-phase microextraction based on amino functionalized carbon nanotube/polypyrrole composite

An electrochemical assistance solid-phase microextraction (EA-SPME) was developed based on amino functionalized multi-walled carbon nanotube/polypyrrole (MWCNTs-NH₂/PPy) composite coating. It was applied for the extraction of eight phenols in food contact material, including 2-chlorophenol, o-cresol, m-cresol, 2,4-dichlorophenol, 4-tert-butylphenol, 4-chlorophenol, 4-tertoctylphenol and alpha-naphthol. MWCNTs-NH₂/PPy coating was characterized by scanning electron microscopy, transmission electron microscope, X-ray energy spectrometer, X-ray diffraction, Fourier transform infrared and thermogravimetric analysis. The adsorption mechanism of phenols on the composite coatings was investigated. The coating modified steel-wire as an extraction fiber has good electroconductibility, reproducibility and long service life. A determination method for the eight phenols was established by EA-SPME coupled with gas chromatography-flame ionization detection. Under the optimal experimental conditions (extraction temperature: 40 °C; extraction time: 30 min; stirring rate: 600 rpm; NaCl concentration: 0.15 g mL^-1; desorption temperature: 250 °C and desorption time: 4 min), the detection linear range was 0.005-50 μg L^-1 (R²>0.99), and the detection limit was 0.001-0.1 μg L^-1 (S/N = 3). For the quintuple analysis of 50 μg L^-1 phenols, the single fiber RSDs were 2.2-12.4%, and the fiber-to-fiber RSDs were 1.9-10.5%. The method was used to detect the migration quantity of the eight phenols from five canned packaging materials, which showed satisfactory recovery 87.3-118.9%.

Bioinspired Neuron-like Adsorptive Networks for Heavy Metal Capture and Tunable Electrochemically Mediated Recovery

Electrochemical techniques have garnered increasing attention as a heavy metal remediation platform for pollutant mitigation and sustainable recycling. Inspired by the biological signal-transfer mode, biomimic neuron-like hierarchical adsorptive networks were constructed by interweaving one-dimensional manganese oxide nanowires into polyaniline-decorated hollow structural metal-organic frameworks (MOFs). The prepared biomimic neuron adsorbent exhibits good adsorption capacity toward cations (Pb²⁺) and oxyanions (Cr₂O₇^2-) at the neutral state; tunable cation/oxyanion desorption can be electrochemically switched at the oxidized and reduced states, respectively, where the biomimic neuron-like hierarchical adsorptive networks facilitated electron transfer and benefited substantial redox reactions. The combination of simulations and calculations demonstrates that the curvature-induced polarization in a hollow MOF structure enhances the desorption efficiencies by improving the redox processes at the electrode-electrolyte interface, which facilitate the promising implementation in terms of water economy and downstream waste sustainability.

Enhanced extraction of organophosphorus pesticides from fruit juices using magnetic effervescent tablets composed of the NiFe2O4@SiO2@PANI-IL nanocomposites

The reported ionic liquid (IL)-based magnetic effervescent tablets are a result of direct addition of ILs and magnetic nanoparticles (MNPs). In effervescent reaction-enhanced microextraction procedures, the dissociation between ILs and MNPs easily leads to loss of ILs due to aqueous solubility, thereby decreasing the extraction efficiency. Herein, we attached a hydrophilic IL ([BMIM]Br) onto the surface of NiFe₂O₄@SiO₂@polyaniline (NiFe₂O₄@SiO₂@PANI-IL) to prepare novel core–shell-like multi-layer nanocomposites. Magnetic effervescent tablets were composed of Na₂CO₃ as an alkaline source, tartaric acid as an acidic source and as-synthesized nanocomposites as an extractant. The nanocomposites were used in an effervescent reaction-enhanced magnetic solid-phase extraction (ERMSE) for the extraction of four organophosphorus pesticides (OPPs) in fruit juices prior to HPLC-DAD detection. Under optimized conditions, this method provided low limits of detection (0.06–0.17 μg L⁻¹), high recoveries (80.6–97.3%) and excellent precision (1.1–5.2%) for OPP quantification in five fruit juices. Notably, the three-layer core–shell nanocomposites were efficiently recycled for at least eight extraction cycles with a recovery loss of <10%. The novelty of this study lies in: (1) for the first time, the ILs-based hybrid magnetic nanocomposites were prepared with appropriate pore size/volume and more active sites for OPPs; (2) the combination of the nanocomposites with effervescent tablets realizes rapid dispersion of CO₂ bubbles, and convenient magnetic separation/collection into one synchronous step; and (3) due to there being no requirement of electrical power, it is feasible for use in field conditions. Thus, the ERMSE method has excellent potential for conventional monitoring of trace-level OPPs in complex fruit juice matrices.

The reported ionic liquid (IL)-based magnetic effervescent tablets are a result of direct addition of ILs and magnetic nanoparticles (MNPs).

Poly (deep eutectic solvents) as a new class of sustainable sorbents for solid phase extraction: application for preconcentration of Pb (II) from food and water samples

A new class of polymeric sorbents based on deep eutectic solvents (DESs) is introduced. These materials are obtained from simple and inexpensive precursors via an energy-efficient process. The primary benefit of these sorbents is that they possess the unique characteristics of DESs and porous materials simultaneously. Moreover, the possibility of tailoring deep eutectic solvents allows designing a specific polymer for a desired analyte, based on its physical and chemical properties. In this work, the deep eutectic solvent of tetrabutylammonium bromide and acrylic acid (1:2 molar ratio) was prepared and then polymerized under solventless condition. The synthesized polymer was characterized by FT-IR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and Brunauer, Emmett and Teller analysis (BET) to evaluate the properties of the sorbent. The poly (TBAB-2AA DES) was applied as a selective sorbent for preconcentration of lead from food and water samples prior to its quantification by flame atomic absorption spectroscopy (FAAS). Variable factors affecting the extraction were optimized, and under the optimum conditions, the calibration plot was linear in the range 5.0-250.0 μg L^-1. The relative standard deviation was (for n = 5) (RSD) < 3%. The limit of detection (LOD) and the enhancement factor were found to be 2.0 μg L^-1 and 50, respectively. Finally, the accuracy of the method was assessed by comparison of the results with those obtained by direct determination of lead using inductively coupled plasma mass spectrometry (ICP-MS) and spiked real samples. The obtained recoveries were between 92 and 106%. Graphical abstract.