Fibers coated with a graphene-polyaniline nanocomposite for the headspace solid-phase microextraction of organochlorine pesticides from seawater samples

Graphene-based nanomaterials as potential candidates for environmental mitigation of pesticides

Over the years, bioaccumulation of hazardous chemicals in the food chain has become a critical issue, resulting in numerous health risks. Environmental mitigation aims to clean up contaminated sites and eliminate hazardous materials from the air, water, or soil to restore the site to its original and safe condition. Pesticides constitute one of the most dangerous environmental pollutants which are generally used to increase crop production. Addressing the removal or treatment of pesticides has become pivotal in mitigating environmental threats. Diverse remediation methods are employed to protect the environment and public health. Graphene-based materials have emerged as promising candidates with exceptional properties, including excellent adsorption capacity due to their high surface area, strong hydrophilicity, and tunable properties. Owing to these properties, they have been attracting major research attention in the field of design and fabrication of materials for the mitigation of pesticides from the environment such as from contaminated food, water and other samples. Various physical, chemical and biological extraction techniques are adopted to remove pesticides. This review article provides an insight into the potential role of graphene-based materials in the environmental remediation of pesticides. We have focused on the removal of Organophosphates, Organochlorines, Carbamates and Pyrethroids present in water, fruit, vegetable and other samples, highlighting the urgent need for environmental remediation. While graphene-based materials hold potential for pesticide remediation, addressing challenges in scalable production, assessing long-term sustainability, and mitigating potential environmental impacts are critical steps for successful large-scale applications.

An ultrastable 2D covalent organic framework coating for headspace solid-phase microextraction of organochlorine pesticides in environmental water

Herein, a quinoline-linked ultrastable 2D covalent organic framework (COF-CN) coated fiber was successfully prepared and used for highly-sensitive headspace solid-phase microextraction (HS-SPME) of organochlorine pesticides (OCPs) in environmental water. The extraction efficiency of the COF-CN coating for all 14 OCPs was higher than that of four commercial SPME fiber coatings and most of the published works, with enrichment factors ranging from 540 to 5065. In combination with gas chromatography-tandem mass spectrometry (GC-MS/MS), a wide linear range (0.05-200 ng/L), low detection limits (LODs, 0.0010-13.54 ng/L) and satisfactory reproducibility and repeatability were obtained under optimal conditions. Compared with the published works, the LODs of the developed technique were improved 2-5.9 times, and the enrichment factors (EFs) of the developed method were enhanced at least 2 times. The COF-CN coated fiber can be easily recycled and reused at least 70 times without any washing step. The adsorption mechanism was first characterized by density functional theory calculations and X-ray photoelectron spectroscopy analysis. Besides, the established method was successfully applied to the analysis of the distribution of trace OCPs in real water samples from Henan Province. All these results proved the promising application of the developed HS-SPME-GC-MS/MS method for organic pollutants analysis in water samples.

Polyaniline and Polyaniline-Based Materials as Sorbents in Solid-Phase Extraction Techniques

Polyaniline (PANI) is one of the best known and widely studied conducting polymers with multiple applications and unique physicochemical properties. Due to its porous structure and relatively high surface area as well as the affinity toward many analytes related to the ability to establish different types of interactions, PANI has a great potential as a sorbent in sample pretreatment before instrumental analyses. This study provides an overview of the applications of polyaniline and polyaniline composites as sorbents in sample preparation techniques based on solid-phase extraction, including conventional solid-phase extraction (SPE) and its modifications, solid-phase microextraction (SPME), dispersive solid-phase extraction (dSPE), magnetic solid-phase extraction (MSPE) and stir-bar sorptive extraction (SBSE). The utility of PANI-based sorbents in chromatography was also summarized. It has been shown that polyaniline is willingly combined with other components and PANI-based materials may be formed in a variety of shapes. Polyaniline alone and PANI-based composites were successfully applied for sample preparation before determination of various analytes, both metal ions and organic compounds, in different matrices such as environmental samples, food, human plasma, urine, and blood.

Fabrication of UMCM-1 based monolithic and hollow fiber - Metal-organic framework deep eutectic solvents/molecularly imprinted polymers and their use in solid phase microextraction of phthalate esters in yogurt, water and edible oil by GC-FID

In this study, for the first time, hollow fiber and monolithic fiber were fabricated based on metal-organic framework deep eutectic solvents/molecularly imprinted polymers (MOF- DES/MIPs) and were used for microextraction of phthalate esters under termed hollow fiber liquid membrane-protected solid-phase microextraction (HFLMP-SPME) followed by gas chromatography- flame ionization detection. Several parameters influencing extraction recoveries of phthalate esters including adsorption and desorption parameters were investigated and optimized using fabricated MOF- DES/MIPs monolithic fiber. Under optimal conditions, detection limits (S/N = 3) of the method were in a range of 0.008-0.03 µg L^-1 and limits of quantification (S/N = 10) were between 0.028 and 0.12 µg L^-1. RSD (%) for intra-day and inter-day precisions were between 2.4-4.7% and 2.6-3.4%, respectively. Subsequently, this procedure was successfully applied with satisfactory results in the determination of phthalate esters in yogurt, water, and soybean oil samples. The R (%) ranged from 95.5 to 100.0% in different samples.

A 3D nanoscale polyhedral oligomeric silsesquioxanes network for microextraction of polycyclic aromatic hydrocarbons

Polyhedral oligomeric silsesquioxanes are 3D nanoscaled materials with large potential in solid phase microextraction (SPME). Here, as a case study, an octaglycidyldimethylsilyl modified polyhedral oligomeric silsesquioxane network is described. It was deposited on a stainless steel wire via a sol-gel method and used as a fiber coating for SPME of aromatic compounds. The uniform pore structure, high surface area, and hydrophobicity of the network make it susceptible toward isolation of non-polar and semi-polar chemical compounds. The performance of the fiber coating was tested with three classes of environmental pollutants, viz. chlorobenzenes (CBs), benzenes (benzene, toluene, ethylbenzene, xylene; known as BTEX), and polycyclic aromatic hydrocarbons. The effects of various types of sol-gel precursors on the fabrication and performance of fiber coatings were investigated. The extraction capability of the fiber coating was compared with the polydimethyl siloxane/divinylbenzene based commercial fiber. Parameters affecting headspace analysis and gas chromatographic quantitation were optimized. The method was applied to the quantification of PAHs, as model analytes, in tea, coffee and some environmental waters. Linear responses typically cover the 1-200 ng·L^-1 concentration range, limits of detection are between 0.1 and 0.3 ng·L^-1, intra-day relative standard deviation are <10%, and inter-day RSDs are <12%. The fiber has a long lifespan and can be used >200 times. Graphical abstract Schematic presentation of a headspace solid phase microextraction process which is implemented to the analysis of PAHs in tea and coffee samples. The SEM image of the SPME fiber coating, the 3D nanoscale polyhedral oligomeric silsesquioxane (POSS) network, and the POSS-epoxy molecular structure are shown.

Monolithic Solid Based on Single-Walled Carbon Nanohorns: Preparation, Characterization, and Practical Evaluation as a Sorbent

A monolithic solid based solely on single walled carbon nanohorns (SWNHs) was prepared without the need of radical initiators or gelators. The procedure involves the preparation of a wet jelly-like system of pristine SWNHs followed by slow drying (48 h) at 25 °C. As a result, a robust and stable porous network was formed due to the interaction between SWNHs not only via π-π and van der Waals interactions, but also via the formation of carbon bonds similar to those observed within dahlia aggregates. Pristine SWNHs and the SWNH monolith were characterized by several techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen intrusion porosimetry. Taking into account the efficiency of carbon nanoparticles in sorption processes, the potential applicability of the SWNH-monolith in this research field was explored using toluene; m-, p-, and o-xylene; ethylbenzene; and styrene, as target analytes. Detection limits were 0.01 µg·L⁻¹ in all cases and the inter-day precision was in the interval 7.4–15.7%. The sorbent performance of the nanostructured monolithic solid was evaluated by extracting the selected compounds from different water samples with recovery values between 81.5% and 116.4%.

Silica Modified with Polyaniline as a Potential Sorbent for Matrix Solid Phase Dispersion (MSPD) and Dispersive Solid Phase Extraction (d-SPE) of Plant Samples

Polyaniline (PANI) is one of the best known conductive polymers with multiple applications. Recently, it was also used in separation techniques, mostly as a component of composites for solid-phase microextraction (SPME). In the present paper, sorbent obtained by in situ polymerization of aniline directly on silica gel particles (Si-PANI) was used for dispersive solid phase extraction (d-SPE) and matrix solid–phase extraction (MSPD). The efficiency of both techniques was evaluated with the use of high performance liquid chromatography with diode array detection (HPLC-DAD) quantitative analysis. The quality of the sorbent was verified by Raman spectroscopy and microscopy combined with automated procedure using computer image analysis. For extraction experiments, triterpenes were chosen as model compounds. The optimal conditions were as follows: protonated Si-PANI impregnated with water, 160/1 sorbent/analyte ratio, 3 min of extraction time, 4 min of desorption time and methanolic solution of ammonia for elution of analytes. The proposed procedure was successfully used for pretreatment of plant samples.

Solid-phase microextraction of volatile organic compounds in headspace of PM-induced MRC-5 cell lines

The exploration of volatile organic compounds (VOCs) produced by cell lines may be a powerful and non-invasive tool for the study of the health risk of human exposure to atmospheric particulate matter (PM). In this work, we developed a sensitive solid phase microextraction-gas chromatography-mass spectrometry method (SPME-GC-MS) to analyze VOCs in breathed gas of PM2.5-induced human embryonic fibroblast cell line (MRC-5). A novel graphene oxide/polyaniline/polydopamine (GO/PANI/PDA) coating was prepared on a stainless steel wire via electrochemical deposition and self-polymerization for the first time. The GO/PANI/PDA coating exhibited high extraction efficiency, good thermal stability (> 380 ℃), excellent mechanical stability as well as long service time (> 150 times). Parameters that may affect the results were optimized systematically. Under the optimal conditions, VOCs including benzene series, aldehydes and alkane were detected with low limit of detection (0.2-2.0 μg L^-1) and good correlation (correlation coefficients above 0.9922). The relative standard deviations of within-day and between-day were 1.1-8.4% and 0.2-11.2%, respectively. Satisfactory recoveries of 82-117% indicated good repeatability of the method. The method has been successfully applied for the determination of target VOCs in the headspace gas of PM2.5-induced MRC-5 cell. And it is expected to provide an alternative tool for the study of cytotoxicology of atmospheric particulates.

The Potential of Graphene as an Adsorbent for Five Pesticides from Different Classes in Rape Oil Samples Using Dispersive Solid-Phase Extraction

Isolation conditions for five pesticides (metazachlor, tebuconazole, λ-cyhalothrin, chlorpyrifos, and deltamethrin) from rape oil samples were examined using the dispersive solid-phase graphene extraction technique. To determine the optimal extraction conditions, a number of experimental factors (amount of graphene, amount of salt, type and volume of the desorbing solvent, desorption time with and without sonication energy, and temperature during desorption) were studied. The compounds of interest were separated and detected by an HPLC-UV employing a Kinetex XB-C18 column and a mobile phase consisting of acetonitrile and water flowing in a gradient mode. The optimized extraction conditions were: the amount of graphene 15 mg, desorbing solvent (acetonitrile) 5 mL, time desorption 10 min at 40°C, and amount of NaCl 1 g. The detection limit for metazachlor, tebuconazole, λ-cyhalothrin, and chlorpyrifos was 62.5 ng·g^-1, and for deltamethrin, it was 500 ng·g^-1. The obtained results lead to the conclusion that graphene may be successfully used for the isolation of the five pesticides from rape oil. However, their determination at low concentration levels, as they occur in real oil samples, requires the employment of appropriately highly sensitive analytical methods, as well as a more suitable graphene form (e.g., magnetically modified graphene).

A novel polyaniline/polypyrrole/graphene oxide fiber for the determination of volatile organic compounds in headspace gas of lung cell lines

Exploration of volatile organic compounds (VOCs) generated by lung cell lines is a powerful and non-invasive tool for the detection of potential volatile biomarkers of lung cancer. In this study, a simple and sensitive solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) method was developed for the determination of VOCs in the headspace gas of lung cell lines. For the purpose of preconcentration, a novel polyaniline/polypyrrole/graphene oxide (PANI/PPy/GO) coating was prepared on the surface of stainless steel fiber via in-situ electrochemical deposition for the first time. The characteristic properties of the coating were studied and the results revealed that the coating possessed large surface area, high extraction efficiency, excellent thermal and mechanical stability as well as long lifespan. Some parameters affecting the extraction efficiency such as synthesis conditions, extraction and desorption conditions were optimized. Under the optimal conditions, the method displayed relatively wide linear range (three or four orders of magnitude) with correlation coefficients above 0.9916. Low detection limits from 1.0 to 12ngL^-1 were obtained. Relative standard deviations ranged from 1.2% to 18.0% indicating good repeatability and reproducibility of the method. This method has been successfully applied to analyze VOCs in the headspace gas of lung adenocarcinoma epithelial cell line (A549) and human embryonic fibroblast cell line (MRC-5).

Graphene/polyaniline electrodeposited needle trap device for the determination of volatile organic compounds in human exhaled breath vapor and A549 cell

In this work, a graphene/polyaniline (G/PANI) electrodeposited coating was introduced as a novel extraction phase of needle trap microextraction (NTME) for the extraction of volatile organic compounds (VOCs).

Application of nanocomposite-based sorbents in microextraction techniques: a review

This review provides a general overview of the recent trends for the preparation of nanocomposites and their applications in microextraction techniques.

A porous carbon derived from amino-functionalized material of Institut Lavoisier as a solid-phase microextraction fiber coating for the extraction of phthalate esters from tea

In this work, a porous carbon derived from amino-functionalized material of Institut Lavoisier (C-NH2 -MIL-125) was prepared and coated onto a stainless-steel wire through sol-gel technique. The coated fiber was used for the solid-phase microextraction of trace levels of phthalate esters (diallyl phthalate, di-iso-butyl ortho-phthalate, di-n-butyl ortho-phthalate, benzyl-n-butyl ortho-phthalate, and bis(2-ethylhexy) ortho-phthalate) from tea beverage samples before gas chromatography with mass spectrometric analysis. Several experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimal conditions, the linearity existed in the range of 0.05-30.00 μg/L for green jasmine tea beverage samples, and 0.10-30.00 μg/L for honey jasmine tea beverage samples, with the correlation coefficients (r) ranging from 0.9939 to 0.9981. The limits of detection of the analytes for the method were 2.0-3.0 ng/L for green jasmine tea beverage sample, and 4.0-5.0 ng/L for honey jasmine tea beverage sample, depending on the compounds. The recoveries of the analytes for the spiked samples were in the range of 82.0-106.0%, and the precision, expressed as the relative standard deviations, was less than 11.1%.

Magnetic graphene-based cyanopropyltriethoxysilane as an adsorbent for simultaneous determination of polar and non-polar organophosphorus pesticides in cow’s milk

A new adsorbent based on magnetic nanoparticles (Fe₃O₄), graphene and cyanopropyltriethoxysilane was fabricated and applied to the magnetic solid phase extraction of organophosphorus pesticides.

Magnetic graphene as modified quick, easy, cheap, effective, rugged and safe adsorbent for the determination of organochlorine pesticide residues in tobacco

In this study, magnetic graphene was used as modified quick, easy, cheap, effective, rugged and safe (QuEChERS) adsorbent for the determination of organochlorine pesticide (OCPs) residues in tobacco. To achieve the optimum conditions of modified QuEChERS procedure toward target analytes, several parameters affecting the clean-up efficiency including the amount of the adsorbent and clean-up time were investigated. Under the optimized conditions, a method for the determination of 26 OCPs residues in tobacco was established by coupling the modified QuEChERS procedure to on-line gel permeation chromatography-gas chromatography-tandem mass spectrometry (on-line GPC-GC-MS(2)). The limits of detection of proposed method for 26 OCPs residues ranged from 0.01275 to 3.150ng/g. And good linearities of the proposed method were obtained with coefficients of determination (R(2)) greater than 0.9985 for all target analytes. Good reproducibility of method was obtained as intra- and inter-day precisions, the relative standard deviations were less than 11.1 and 15.0%, respectively. The apparent recoveries were in the range of 64-126% at different concentrations for real samples. Compared with the reported methods for the determination of OCPs residues in tobacco, the proposed method has the advantages of simple to operate, low cost and high clean-up ability. Finally, the method was successfully applied to the analysis of OCPs residues in real samples.

Graphene-Based Materials as Solid Phase Extraction Sorbent for Trace Metal Ions, Organic Compounds, and Biological Sample Preparation

Graphene is a new carbon-based material that is of interest in separation science. Graphene has extraordinary properties including nano size, high surface area, thermal and chemical stability, and excellent adsorption affinity to pollutants. Its adsorption mechanisms are through non-covalent interactions (π-π stacking, electrostatic interactions, and H-bonding) for organic compounds and covalent interactions for metal ions. These properties have led to graphene-based material becoming a desirable adsorbent in a popular sample preparation technique known as solid phase extraction (SPE). Numerous studies have been published on graphene applications in recent years, but few review papers have focused on its applications in analytical chemistry. This article focuses on recent preconcentration of trace elements, organic compounds, and biological species using SPE-based graphene, graphene oxide, and their modified forms. Solid phase microextraction and micro SPE (µSPE) methods based on graphene are discussed.

Graphene-based materials: fabrication and application for adsorption in analytical chemistry

Graphene, a single layer of carbon atoms densely packed into a honeycomb crystal lattice with unique electronic, chemical, and mechanical properties, is the 2D allotrope of carbon. Owing to the remarkable properties, graphene and graphene-based materials are likely to find potential applications as a sorbent in analytical chemistry. The current review focuses predominantly on the recent development of graphene-based materials and demonstrates their enhanced performance in adsorption of organic compounds, metal ions, and solid phase extraction as well as in separation science since mostly 2012.