Review of nanomaterials as sorbents in solid-phase extraction for environmental samples

Nitrophenols in the environment: An update on pretreatment and analysis techniques since 2017

Nitrophenols, a versatile intermediate, have been widely used in leather, medicine, chemical synthesis, and other fields. Because these components are widely applied, they can enter the environment through various routes, leading to many hazards and toxicities. There has been a recent surge in the development of simple, rapid, environmentally friendly, and effective techniques for determining these environmental pollutants. This review provides a comprehensive overview of the latest research progress on the pretreatment and analysis methods of nitrophenols since 2017, with a focus on environmental samples. Pretreatment methods include liquid-liquid extraction, solid-phase extraction, dispersive extraction, and microextraction methods. Analysis methods mainly include liquid chromatography-based methods, gas chromatography-based methods, supercritical fluid chromatography. In addition, this review also discusses and compares the advantages/disadvantages and development prospects of different pretreatment and analysis methods to provide a reference for further research.

Synthesis of imidazolium ionic liquid immobilized on magnetic mesoporous silica: A sorbent material in a green micro-solid phase extraction of multiclass pesticides in water

In this study, we synthesized an imidazolium ionic liquid immobilized on magnetic mesoporous silica (IL-MMS) and evaluated its performance as a sorbent material for a green micro-solid phase extraction (μ-SPE) of multiclass pesticides in water. The synthesized IL-MMS was characterized by various analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses (N2 adsorption/desorption), Vibrating Sample Magnetometer (VSM), energy-dispersive spectroscopy (EDS) and Field emission scanning electron microscopy (FESEM). Our synthesized IL-MMS demonstrated excellent magnetic properties (31.5 emu/g), high surface area (1177.4 m2/g), proper pore size (⁓4.2 nm) and volume (1.80 cm3/g). Under optimized extraction conditions, the IL-MMS exhibited a high adsorption capacity for a variety of pesticides, including organophosphates, carbamates, and pyrethroids. The proposed μ-SPE method using IL-MMS showed good linearity (R2 > 0.99), low limits of detection (LODs) ranging from 0.04 to 1.63 ng/L, and suitable recovery rate was between 82.4% and 109.8% for different pesticides. In addition, the method also exhibited excellent reproducibility, with relative standard deviations (RSDs) of less than 8% for both intra and inter-day precision. In overall, the synthesized IL-MMS has proven to be a highly promising material for sorbent-based micro-solid phase extraction (μ-SPE) of multiclass pesticides in water. With its simple, efficient, and eco-friendly approach to pesticide analysis, this method shows great potential for future pesticide detection and monitoring efforts due to its sensitivity, accuracy, and adaptability to various environmental conditions.

The role of sustainable materials in sample preparation

Sample preparation is a constantly evolving step in the measurement process with a positive effect on its performance. Its evolution has been marked by an underlying environmental commitment, with simplification, miniaturization, and automation being three of its driving forces. This trends article deepens how the sample preparation can go sustainable through the efficient design of new sorptive materials, either liquid or solid. This objective can be achieved by using natural and/or biodegradable materials as precursors of the functional sorptive phases and by designing materials that simplify the procedures (thus reducing the energy or resources required). Although environmental performance is a crucial aspect of a new material, its applicability is what really defines its incorporation into the sample preparation toolbox. For this reason, their characteristics and more relevant applications will be briefly presented to conclude with the tendency of their use in the very near future.

Application of three-dimensional material CZIF-8/CS-MS as adsorbents for the determination of plant growth regulators in Schisandra chinensis

In this study, we employed a melamine sponge (MS) as the skeleton material and utilized carbonized ZIF-8 (CZIF-8) and chitosan (CS) as the raw materials to prepare CZIF-8/CS-MS, a novel material featuring a three-dimensional interconnected porous network. The resulting CZIF-8/CS-MS material possesses a unique porous structure, significant specific surface area and abundant active sites. These characteristics make CZIF-8/CS-MS a promising absorbent for selective purification of plant growth regulators (PGRs) including 1-naphthlcetic acid (NAA), naphthoxyacetic acid (NOA), 4-chlorophenoxyacetic acid (4-CPA), 2,4-dichlorophenoxyacetic acid (2,4-D). After optimizing the extraction conditions, excellent linearity (r > 0.9994) was observed within a wide linear range of 1-100 ng/mL using ultra high performance liquid chromatography-tandem quadrupole mass spectrometry. The detection limits (LODs) and limits of quantification (LOQs) were found to be in the range of 0.013-0.154 ng/mL and 0.044-0.515 ng/mL, respectively. Additionally, the relative recovery of Schisandra chinensis fruit samples was determined to be 89.7-99.4 %, with a relative standard deviation (RSDs) of ≤ 8.4 % (n = 3). Compared to other methods, this approach offers a multitude of benefits, which include but are not limited to exceptional sensitivity, reduced sample volume requirements, low LODs, a comparable linear range, and high reproducibility. The findings of this study pave the way for exploring novel functionalized sponge columns, which leverage the integration of nano-sorbent materials and coating agents, for the purpose of analyzing PGRs within intricate matrix samples.

Trapping of heavy metal ions from electroplating wastewater with phosphorylated double-shelled hollow spheres

The mesoporous multi-shelled hollow structures are promising for trapping of non-degradable heavy metal ions in wastewater but difficult to synthesize. We successfully demonstrated a simple strategy for the construction of mesopore windows on double-shelled α-Fe2O3 hollow spheres. A step-by-step proof of concept synthesis mechanism has been revealed by using mainly electron microscopy and thermogravimetric analysis. We proved that mesopore windows are indispensable to realize the complete surface coverage of phosphonate ligands on α-Fe2O3 double-shelled hollow spheres. The phosphonic groups inherently coordinated with Ni(II) and Cu(II) ions and formed complexes of high stability. Importantly, owing to the structural merits, the phosphorylated double-shelled hollow spheres selectively removes Ni(II) and Cu(II) at wider sample pH range with a high capacity of 380 mg g-1 and 410 mg g-1, respectively. In addition, no significant decrease in the removal efficiency was observed under high salt matrix. For electroplating industry wastewater, the novel structure performs simultaneous Ni(II) and Cu(II) removal, thus producing effluent of stable quality that meets local discharge regulations.

Recent progress of covalent organic frameworks as attractive materials for solid-phase microextraction: A review

Solid-phase microextraction (SPME) is a green, environmentally friendly, and efficient technique for sample pre-treatment. Covalent organic frameworks (COFs), a class of porous materials formed by covalent bonds, have gained prominence owing to their remarkable attributes, including large specific surface area, tunable pore size, and robust thermal/chemical stability. These characteristics have made COFs highly appealing as potential coatings for SPME fiber over the past decades. In this review, various methods used to prepare SPME coatings based on COFs are presented. These methods encompass physical adhesion, sol-gel processes, in situ growth, and chemical cross-linking strategies. In addition, the applications of COF-based SPME coating fibers for the preconcentration of various targets in environmental, food, and biological samples are summarized. Moreover, not only their advantages but also the challenges they pose in practical applications are highlighted. By shedding light on these aspects, this review aims to contribute to the continued development and utilization of COF materials in the field of sample pretreatment.

Decoding Cosmetic Complexities: A Comprehensive Guide to Matrix Composition and Pretreatment Technology

Despite advancements in analytical technologies, the complex nature of cosmetic matrices, coupled with the presence of diverse and trace unauthorized additives, hinders the application of these technologies in cosmetics analysis. This not only impedes effective regulation of cosmetics but also leads to the continual infiltration of illegal products into the market, posing serious health risks to consumers. The establishment of cosmetic regulations is often based on extensive scientific experiments, resulting in a certain degree of latency. Therefore, timely advancement in laboratory research is crucial to ensure the timely update and adaptability of regulations. A comprehensive understanding of the composition of cosmetic matrices and their pretreatment technologies is vital for enhancing the efficiency and accuracy of cosmetic detection. Drawing upon the China National Medical Products Administration's 2021 Cosmetic Classification Rules and Classification Catalogue, we streamline the wide array of cosmetics into four principal categories based on the following compositions: emulsified, liquid, powdered, and wax-based cosmetics. In this review, the characteristics, compositional elements, and physicochemical properties inherent to each category, as well as an extensive overview of the evolution of pretreatment methods for different categories, will be explored. Our objective is to provide a clear and comprehensive guide, equipping researchers with profound insights into the core compositions and pretreatment methods of cosmetics, which will in turn advance cosmetic analysis and improve detection and regulatory approaches in the industry.

Fe3O4@UiO-66-NH2 based on magnetic solid phase extraction for determination of organic UV filters in environmental water samples

In this work, a nanocomposite structured magnetic metal-organic framework named as Fe3O4@UiO-66-NH2 was prepared via a simple hydrothermal approach. The as-mentioned nanocomposite was characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and the Brunauer-Emmett-Teller (BET) techniques. Using the Fe3O4@UiO-66-NH2 as a nanosorbent, an easy and highly effective approach was developed to preconcentrate nine organic UV filters before gas chromatography-mass spectrometry (GC-MS) analysis. Different conditions influencing the extraction efficiency encompassing the sorbent amount, nature and volume of desorption solvent, desorption time, pH of the sample, and extraction time, were examined. Under the optimal experimental parameters, the Fe3O4@UiO-66-NH2-based magnetic solid phase extraction and GC-MS (MSPE-GC-MS) demonstrated linearity in the range of 0.03-1500 ng/L (R2 ≥ 0.9974) and the reproducibility, expressed as RSD, was ≤7.5%. The limits of detection ranged between 0.01 and 0.07 ng/L and limits of quantification were in the range of 0.03-0.4 ng/L. Finally, the suggested approach was satisfactorily utilized to determine nine organic UV filters in different water samples (analytical recoveries between 86.5% and 104.2%).

Cellulose-based adsorbents for solid phase extraction and recovery of pharmaceutical residues from water

Cellulose has attracted interest from researchers both in academic and industrial sectors due to its unique structural and physicochemical properties. The ease of surface modification of cellulose by the integration of nanomaterials, magnetic components, metal organic frameworks and polymers has made them a promising adsorbent for solid phase extraction of emerging contaminants, including pharmaceutical residues. This review summarizes, compares, and contrasts different types of cellulose-based adsorbents along with their applications in adsorption, extraction and pre-concentration of pharmaceutical residues in water for subsequent analysis. In addition, a comparison in efficiency of cellulose-based adsorbents and other types of adsorbents that have been used for the extraction of pharmaceuticals in water is presented. From our observation, cellulose-based materials have principally been investigated for the adsorption of pharmaceuticals in water. However, this review aims to shift the focus of researchers to the application of these adsorbents in the effective pre-concentration of pharmaceutical pollutants from water at trace concentrations, for quantification. At the end of the review, the challenges and future perspectives regarding cellulose-based adsorbents are discussed, thus providing an in-depth overview of the current state of the art in cellulose hybrid adsorbents for extraction of pharmaceuticals from water. This is expected to inspire the development of solid phase exraction materials that are efficient, relatively cheap, and prepared in a sustainable way.

Electrochemical sensor based on carbon nanotube decorated with manganese oxide nanoparticles for naphthalene determination

In this work, an electrochemical sensor was developed for the determination of naphthalene (NaP) in well water samples, based on a glass carbon electrode (GCE) modified as a nanocomposite of manganese oxides (MnOx) and COOH-functionalized multi-walled carbon nanotubes (MWCNT). The synthesis of MnOx nanoparticles was performed by the sol-gel method. The nanocomposite was obtained by mixing MnOx and MWCNT with the aid of ultrasound, followed by stirring for 24 h. Surface modification facilitated the electron transfer process through the MnOx/MWCNT/GCE composite, which was used as an electrochemical sensor. The sensor and its material were characterized by cyclic voltammetry (CV), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Important parameters influencing electrochemical sensor performance (pH, composite ratios) were investigated and optimized. The MnOx/MWCNT/GCE sensor showed a wide linear range of 2.0-16.0 μM, a detection limit of 0.5 μM and a quantification limit of 1.8 μM, in addition to satisfactory repeatability (RSD of 7.8%) and stability (900 s) in the determination of NaP. The determination of NaP in a sample of water from a gas station well using the proposed sensor showed results with recovery between 98.1 and 103.3%. The results obtained suggest that the MnOx/MWCNT/GCE electrode has great potential for application in the detection of NaP in well water.

TiO2 nanoparticle-Coated 3D-Printed porous monoliths enabling highly sensitive speciation of inorganic Cr, As, and Se

Post-printing functionalization can enhance the functionality and applicability of analytical devices manufactured using three-dimensional printing (3DP) technologies. In this study we developed a post-printing foaming-assisted coating scheme-through respective treatments with a formic acid (30%, v/v) solution and a sodium bicarbonate (0.5%, w/v) solution incorporating titanium dioxide nanoparticles (TiO2 NPs; 1.0%, w/v)-for in situ fabrication of TiO2 NP-coated porous polyamide monoliths in 3D-printed solid phase extraction columns, thereby enhancing the extraction efficiencies of Cr(III), Cr(VI), As(III), As(V), Se(IV), and Se(VI) for speciation of inorganic Cr, As, and Se species in high-salt-content samples when using inductively coupled plasma mass spectrometry. After optimizing the experimental conditions, the 3D-printed solid phase extraction columns with the TiO2 NP-coated porous monoliths extracted these species with 5.0- to 21.9-fold enhancements, relative to those obtained with the uncoated monolith, with absolute extraction efficiencies ranging from 84.5 to 98.3% and method detection limits ranging from 0.7 to 32.3 ng L-1. We validated the reliability of this multi-elemental speciation method through determination of these species in four reference materials [CASS-4 (nearshore seawater), SLRS-5 (river water), 1643f (fresh water), and Seronorm Trace Elements Urine L-2 (human urine); relative errors between certified and measured concentrations: 5.6 to +4.0%] and spike analyses of seawater, river water, agriculture waste, and human urine samples (spike recoveries: 96-104%; relative standard deviations of these measured concentrations all below 4.3%). Our results demonstrate that post-printing functionalization has great potential for future applicability in 3DP-enabling analytical methods.

An overview of biogenic metallic nanoparticles for water treatment and purification: the state of the art

The environment is fundamental to human existence, and protecting it from dangerous contaminants should be a top priority for all stakeholders. Reducing garbage output has helped, but as the world's population grows, more waste will be generated. Tons of waste inadvertently and advertently received by environmental matrixes adversely affect the sustainable environment. The pollution caused by these activities affects the environment and human health. Conventional remediation processes ranging from chemical, physical, and biological procedures use macroaggregated materials and microorganisms to degrade or remove pollutants. Undesirable limitations of expensiveness, disposal challenges, maintenance, and formation of secondary contaminants abound. Additionally, multiple stages of treatments to remove different contaminants are time-consuming. The need to avoid these limitations and shift towards sustainable approaches brought up nanotechnology options. Currently, nanomaterials are being used for environmental rejuvenation that involves the total degradation of pollutants without secondary pollution. As nanoparticles are primed with vast and modifiable reactive sites for adsorption, photocatalysis, and disinfection, they are more useful in remediating pollutants. Review articles on metallic nanoparticles usually focus on chemically synthesized ones, with a particular focus on their adsorption capacity and toxicities. Therefore, this review evaluates the current status of biogenic metallic nanoparticles for water treatment and purification.

CNTs intercalated graphene oxide with interspersed MoS2 nanoparticles for selective preconcentration and determination of trace Hg(II) ions

The carbon nanotubes (CNT) intercalated graphene oxide (GO) nanosheets was functionalized with molybdenum disulfide nanoparticles (MSNP). Intercalation of CNT in between GO nanosheets significantly enhances porosity and avail both surfaces of GO for MSNP decoration. High porosity and densely populated MSNP led to faster Hg(II) ions diffusion and sorption. The material shows high selectivity for Hg(II) sorption due to sulfur rich sites. The GO/CNT@MSNP packed column employed for trace Hg(II) preconcentration and determination in fish, rice, mushroom, sunflower seeds and river and ground water samples. No significant hindrances by co-existing matrices in the determination of Hg(II) was found. The method shows a preconcentration factor of 540 and a preconcentration limit of 0.37 μg L^-1. The method detection limit was found to be 0.03 μg L^-1 and a good precision (RSD 4.2%). The Student's t test score was lower than critical Student's t value of 4.303 at the 95% confidence level. ENVIRONMENTAL IMPLICATION: Metal ions toxicity is a global issue and their trace level analysis from complex matrices is remains challenging. SPE of trace Hg(II) by graphene oxide is challenging due to agglomeration and less selectivity, nevertheless of its high surface area. We prepared a Hg(II) selective nanocomposite of MoS₂ quantum dots grows onto GO surface. The hybrid nanocomposite selectively adsorbed Hg(II) ions from complex sample matrices. Compared to a nascent GO membrane, it were more efficient to preconcentrate and determine Hg(II) from real samples and provide more accurate data for environmental monitoring and assessment of action plan to control the Hg(II) pollution.

Dispersive Micro-Solid Phase Extraction Using a Graphene Oxide Nanosheet with Neocuproine and Batocuproine for the Preconcentration of Traces of Metal Ions in Food Samples

A dispersive micro-solid phase extraction (Dµ-SPE) method for the preconcentration of trace metal ions (Pb, Cd, Cr, Mn, Fe, Co, Ni, Cu, Zn) on graphene oxide with the complexing reagents neocuproine or batocuproine is presented here. Metal ions form cationic complexes with neocuproine and batocuproine. These compounds are adsorbed on the GO surface via electrostatic interactions. The factors affecting the separation and preconcentration of analytes such as pH, eluent (concentration, type, volume), amount of neocuproine, batocuproine and GO, mixing time, and sample volume were optimized. The optimal sorption pH was 8. The adsorbed ions were effectively eluted with 5 mL 0.5 mol L^-1 HNO₃ solution and determined by the ICP-OES technique. The preconcentration factor for the GO/neocuproine and GO/batocuproine in the range 10-100 and 40-200 was obtained for the analytes, with detection limits of 0.035-0.84 ng mL^-1 and 0.047-0.54 ng mL^-1, respectively. The method was validated by the analysis of the three certified reference materials: M-3 HerTis, M-4 CormTis, and M-5 CodTis. The procedure was applied to determine metal levels in food samples.

Novel amino-functionalized magnetic metal-organic framework/layered double hydroxide adsorbent for microfluidic solid phase extraction: Application for vitamin D3

Vitamin D deficiency is highly prevalent worldwide, especially with limited sun exposure and sun avoidance. Thus, reliable monitoring of vitamin D levels in food and biological samples is vital for medicinal diagnosis. Herein, a potent method for the extraction and determination of vitamin D₃ is presented using a microchip-based solid-phase extraction (SPE) device followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. A new magnetic adsorbent based on Fe₃O₄ magnetic nanoparticles (MNPs) modified ZnFe layered double hydroxide (LDH)/2-aminoterephthalic acid-Zn²⁺ metal-organic framework (IRMOF-3) composite (IRMOF-3@MLDH) was successfully synthesized and fixed inside a rectangular micro-column (4 × 2 × 12 mm). The porous structure and high surface area of IRMOF-3@MLDH provide abundant adsorbing sites and make it a potent SPE adsorbent, with an exceptional ability to retain vitamin D₃. The adsorption isotherm showed that the composite was highly efficient at extracting vitamin D₃ with an extraction capacity of 126 mg g^-1. The designed extraction microchip simplified the SPE process, paving the way for automated SPE systems. The developed method presented a broad linear range of 5-2000 ng mL^-1, with a detection limit of 1.4 ng mL^-1. In comparison to conventional silica-based adsorbents, a higher sensitivity was obtained in the determination of vitamin D₃ using the IRMOF-3@MLDH adsorbent. The selectivity of the method was also satisfactory, enabling the measurement of vitamin D₃ in food and blood samples with high recovery values in the range from 95.2 to 101%. Thus, the newly developed adsorbent and method offer an efficient alternative to the commonly used C18-based approach.

From polyethylene waste bottles to UIO-66 (Zr) for preconcentration of steroid hormones from river water

Metal-organic framework (UiO-66 (Zr) was synthesized using polyethylene terephthalate (PET) and used as an adsorbent for extraction and preconcentration of steroid hormones in river water. Polyethylene waste bottles were used as the source of polyethylene terephthalate (PET) ligands. The UIO-66(Zr), which the PET was made from recycled waste plastics, was used for the first time for the extraction and preconcentration of four different types of steroid hormones in river water samples. Various analytical characterization techniques were employed to characterize the synthesized material. The steroid hormones were detected and quantified using high-performance liquid chromatography coupled with diode array detector (HPLC-DAD). The results were further validated using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Experimental variables, such as sample pH, the mass of adsorbent and extraction time, were optimized using Box-Behnken design (BBD). The dispersive solid phase extraction method combined with HPLC-DAD, displayed good linearity (0.004-1000 µg/L) low limits of detections (LODs, 1.1-16 ng/L for ultrapure water and 2.6-5.3 ng/L for river water) and limits of quantification (LOQs, 3.7-5.3 ng/L for ultrapure water and 8.7-11.0 ng/L for river water samples) and acceptable extraction recoveries (86-101%). The intraday (n = 10) and interday (n = 5) precisions expressed in terms of relative standard deviations (%RSD) were all less than 5%. The steroid hormones were detected in most of the river water samples (Vaal River and Rietspruit River). The DSPE/HPLC method offered a promising approach for simultaneous extraction, preconcentration and determination of steroid hormones in water.

Preparation of a single and reusable biopolymer-based film for the extraction and preconcentration of anti-inflammatory drugs from environmental water samples

One of the main goals of green chemistry is to reduce the use of toxic materials and the generation of hazardous waste, both during method development and in the synthesis of the materials used. Thus, a biodegradable, single and reusable material composed of agarose and multi-walled carbon nanotubes was proposed. The film preparation was carefully optimized in order to obtain a one-piece sorbent, with high extraction efficiency and the possibility of reuse. The film was tested in the simultaneous extraction and preconcentration of three non-steroidal anti-inflammatory drugs (ketorolac, ketoprofen and piroxicam) from environmental water samples. The optimal extraction parameters were as follows: isopropyl alcohol as the activation solvent, a sample pH value of 3.0, extraction time of 30 min, 2.00 mL of acetonitrile as the eluent, an elution time of 5 minutes, and a sample volume of 250.00 mL. Under these conditions, the film was reusable 50 times without losing its extraction capacity significantly. HPLC with a photodiode array detector was used for the separation and determination. The method presented a linear range between 0.10 and 1.2 μg L^-1, good sensitivity with limits of detection between 0.0075 and 0.0089 μg L^-1, and quantification between 0.025 and 0.030 μg L^-1. In addition, low RSD values (0.46-3.13%) were obtained demonstrating satisfactory precision. Stream water samples were analyzed, and recoveries between 82.0 and 109.0% were obtained.

Magnetic Solid-Phase Extraction Based on Silica and Graphene Materials for Sensitive Analysis of Emerging Contaminants in Wastewater with the Aid of UHPLC-Orbitrap-MS

With the advancement of technology and nanotechnology, new extraction sorbents have been created and effectively used for the magnetic solid-phase extraction of target analytes. Some of the investigated sorbents have better chemical and physical properties, exhibiting high extraction efficiency and strong repeatability, combined with low detection and quantification limits. In this study graphene oxide (GO) magnetic composites were prepared and used as magnetic solid-phase extraction (MSPE) adsorbents along with synthesized silica based magnetic nanoparticles (MNPs) functionalized with the C18 group for the preconcentration of emerging contaminants (ECs) in wastewater samples generated from hospital and urban facilities. The sample preparation with magnetic materials was followed by UHPLC-Orbitrap MS analysis for the accurate identification and determination of trace amounts of pharmaceutical active compounds and artificial sweeteners in effluent wastewater. Optimal conditions were used for the extraction of ECs from the aqueous samples, prior to UHPLC-Orbitrap MS determination. The proposed methods achieved low quantitation limits between 1.1-33.6 ng L^-1 and 1.8-98.7 ng L^-1 and satisfactory recoveries in the range of 58.4%-102.6%. An intra-day precision of less than 23.1% was achieved, while inter-day RSD% values in the range of 5.6-24.8% were observed. These figures of merit suggest that our proposed methodology is suitable for the determination of target ECs in aquatic systems.

Advances on Hormones in Cosmetics: Illegal Addition Status, Sample Preparation, and Detection Technology

Owing to the rapid development of the cosmetic industry, cosmetic safety has become the focus of consumers' attention. However, in order to achieve the desired effects in the short term, the illegal addition of hormones in cosmetics has emerged frequently, which could induce skin problems and even skin cancer after long-term use. Therefore, it is of great significance to master the illegal addition in cosmetics and effectively detect the hormones that may exist in cosmetics. In this review, we analyze the illegally added hormone types, detection values, and cosmetic types, as well as discuss the hormone risks in cosmetics for human beings, according to the data in unqualified cosmetics in China from 2017 to 2022. Results showed that although the frequency of adding hormones in cosmetics has declined, hormones are still the main prohibited substances in illegal cosmetics, especially facial masks. Because of the complex composition and the low concentration of hormones in cosmetics, it is necessary to combine efficient sample preparation technology with instrumental analysis. In order to give the readers a comprehensive overview of hormone analytical technologies in cosmetics, we summarize the advanced sample preparation techniques and commonly used detection techniques of hormones in cosmetics in the last decade (2012-2022). We found that ultrasound-assisted extraction, solid phase extraction, and microextraction coupled with chromatographic analysis are still the most widely used analytical technologies for hormones in cosmetics. Through the investigation of market status, the summary of sample pretreatment and detection technologies, as well as the discussion of their development trends in the future, our purpose is to provide a reference for the supervision of illegal hormone residues in cosmetics.

Application of response surface modeling optimization in UV spectrophotometric determination of 4-aminobenzoic acid by molecularly imprinted polypyrrole

Selective determination of 4-aminobenzoic acid (ABA) in pharmaceutical and human serum samples was performed by molecularly imprinted polypyrrole and ultraviolet (UV) spectrophotometry, based on precipitation polymerization. The molecularly imprinted polymer (MIP) was prepared using pyrrole functional monomer and ABA template molecules. The significant factors controlling the performance of the synthesized ABAMIP sorbent were screened and optimized using Plackett- Burman design (PBD) and central composite design (CCD), respectively. The model was used to obtain the optimal values of the significant response factors. The predicted MIP to NIP response ratio demonstrated an approximate deviation of 5 % from the experimental value. Under the obtained optimal conditions, the calibration curve showed a linear range of 0.05-2 mM with a correlation coefficient (r²) of 0.9920 and a limit of detection (LOD) of 0.0310 mM. The method recovery for the analyte was obtained 88.10-100.5 in the investigated real samples. The proposed ABA-MIP sorbent showed an acceptable selectivity in the presence of some pharmaceuticals.

Preconcentration and Removal of Pb(II) Ions from Aqueous Solutions Using Graphene-Based Nanomaterials

Direct determination of lead trace concentration in the presence of relatively complex matrices is often a problem. Thus, its preconcentration and separation are necessary in the analytical procedures. Graphene-based nanomaterials have attracted significant interest as potential adsorbents for Pb(II) preconcentration and removal due to their high specific surface area, exceptional porosities, numerous adsorption sites and functionalization ease. Particularly, incorporation of magnetic particles with graphene adsorbents offers an effective approach to overcome the separation problems after a lead enrichment step. This paper summarizes the developments in the applications of graphene-based adsorbents in conventional solid-phase extraction column packing and its alternative approaches in the past 5 years.

Evaluation of the antimicrobial effects of Capsicum, Nigella sativa, Musa paradisiaca L., and Citrus limetta: A review

The extensive use of antibiotics and vaccines against microbial infections can result in long-term negative effects on humans and the environment. However, there are a number of plants that have antimicrobial effects against various disease-causing microbes such as bacteria, viruses, and fungi without negative side effects or harm to the environment. In this regard, four particular plants- Capsicum, Nigella sativa, Musa paradisiaca L., and Citrus limetta have been widely considered due to their excellent antimicrobial effect and ample availability. In this review, we discuss their antimicrobial effects due to the presence of thymoquinone, p-cymene, pinene, alkaloids, limonene, camphene, and melanin. These antimicrobial compounds disrupt the cell membrane of microbes, inhibit cellular division, and form biofilm in bacterial species, eventually reducing the number of microbes. Extraction of these compounds from the respective plants is carried out by different methods such as soxhlet, hydro-distillation, liquid-liquid extraction (LLE), pressurized liquid extraction (PLE), solid-phase extraction (SPE), supercritical fluid extraction (SFE), pulsed electric field (PEF), microwave-assisted extraction (MAE), enzyme-assisted extraction (EAE), ultrasound-assisted extraction (UAE), and high-voltage electrical discharge. Suitable selection of the extraction technique highly depends upon the associated advantages and disadvantages. In order to aid future study in this field, this review paper summarizes the advantages and disadvantages of each of these approaches. Additionally, the discussion covers how antimicrobial agents destroy harmful bacteria. Thus, this review offers in-depth knowledge to researchers on the antibacterial properties of Capsicum, Nigella sativa, Musa paradisiaca L. peels, and Citrus limetta.

Nickel hydroxide nanoflower-based dispersive solid-phase extraction of copper from water matrix

In this work, a dispersive solid-phase extraction method based on Ni(OH)₂ nanoflowers (Ni(OH)₂-NFs-DSPE) was developed to separate and preconcentrate copper ions from tap water samples for determination by flame atomic absorption spectrometry (FAAS). Ni(OH)₂-NFs was synthesized using a homogeneous precipitation technique and used as sorbent for copper preconcentration. X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to characterize the synthesized sorbent. All experimental variables were carefully optimized to achieve a high enhancement factor of 107.5-folds with respect to the detection sensitivity of the conventional FAAS. The proposed method's analytical parameters including LOD, LOQ, and linear range were determined as 1.33 μg/L, 4.42 μg/L, and 3.0-40 μg/L, respectively. To assess the applicability and reliability of the developed method, optimal conditions were applied to tap water samples and satisfactory percent recoveries (94-103%) were obtained for the samples spiked at 20 and 30 μg/L. This validated the accuracy and feasibility of the developed method to real samples. The developed method can be described as a simple, efficient, and rapid analytical approach for the accurate determination of trace copper ions in water samples.

Degradation of Xenobiotic Pollutants: An Environmentally Sustainable Approach

The ability of microorganisms to detoxify xenobiotic compounds allows them to thrive in a toxic environment using carbon, phosphorus, sulfur, and nitrogen from the available sources. Biotransformation is the most effective and useful metabolic process to degrade xenobiotic compounds. Microorganisms have an exceptional ability due to particular genes, enzymes, and degradative mechanisms. Microorganisms such as bacteria and fungi have unique properties that enable them to partially or completely metabolize the xenobiotic substances in various ecosystems.There are many cutting-edge approaches available to understand the molecular mechanism of degradative processes and pathways to decontaminate or change the core structure of xenobiotics in nature. These methods examine microorganisms, their metabolic machinery, novel proteins, and catabolic genes. This article addresses recent advances and current trends to characterize the catabolic genes, enzymes and the techniques involved in combating the threat of xenobiotic compounds using an eco-friendly approach.

Size characterization of nanomaterials in environmental and biological matrices through non-electron microscopic techniques

Engineered nanomaterials (ENs) can enter the environment, and accumulate in food chains, thereby causing environmental and health problems. Size characterization of ENs is critical for further evaluating the interactions among ENs in biological and ecological systems. Although electron microscope is a powerful tool in obtaining the size information, it has limitations when studying nanomaterials in complex matrices. In this review, we summarized non-electron microscope-based techniques, including chromatography-based, mass spectrometry-based, synchrotron radiation- and neutron-based techniques for detecting the size of ENs in environmental and biological matrices. The advantages and disadvantages of these techniques were highlighted. The perspectives on size characterization of ENs in complex matrices were also presented.

An ion imprinted magnetic organosilica nanocomposite for the selective determination of traces of Cd(II) in a minicolumn flow-through preconcentration system coupled with graphite furnace atomic absorption spectroscopy

In this paper we present the determination of ultratraces of cadmium ions in water by means of a minicolumn (MC) flow-through preconcentration system coupled with graphite furnace atomic absorption spectrometry. The core of the system is a lab-made ion imprinted magnetic organosilica nanocomposite which is employed as filler of the MC for the selective retention of the analyte. In this case superparamagnetic magnetite nanoparticles were coated with an amine-functionalized shell and ion imprinted with Cd(II) by a simple sol-gel co-condensation method. The setup was completed with the inclusion of a magnet fixed around the packed MC. This assembly - which is studied with an MII material for the first time here - allowed a homogeneous distribution of the solid on the walls of the MC, leaving a hole in the center and enabling the absence of material bleeding or obstructions to the free movement of fluids. Ion imprinted (MII) and non-imprinted (MNI) materials were studied for comparison purposes. Both were characterized and compared by DRX, FTIR, and SEM and their magnetic behavior by magnetization curves. Batch experiments showed an equilibration time of less than 10 minutes and a maximum adsorption pH of around 7 for both solids. The maximum capacity for MII was greater than that of MNI (200 mg g^-1 and 30 mg g^-1 respectively) and thus, the former was chosen for analytical purposes. Under MC dynamic conditions, sample and elution flow rates, volumes of the sample and eluant, and type and concentration of the most suitable eluant have been thoroughly investigated and optimized. Under the optimal experimental conditions, the MII filler showed a preconcentration factor of 200, a limit of detection of 0.64 ng L^-1, a linear range of 2.5-100 ng L^-1, RSD% of 1.9 (n = 6; 10 ng L^-1) and a lifetime of more than 800 cycles of concentration-elution with no loss of sensitivity or need for refilling. The effect of potentially interfering ions on the percent recovery of cadmium was also studied. The proposed method was successfully applied to the determination of traces of Cd(II) in osmosis and tap water with recoveries of 98.0-101.3%. A comparison with similar methods is also provided.

Development of sol-gel silica-based mixed-mode zwitterionic sorbents for determining drugs in environmental water samples

Four novel mixed-mode zwitterionic silica-based functionalized with strong moieties sorbents were synthesized and evaluated through solid-phase extraction (SPE) to determine acidic and basic drugs in environmental water samples. All sorbents had the same functionalization: quaternary amine and sulfonic groups and C₁₈ chains so that hydrophobic and strong cationic exchange (SCX) and strong anionic exchange (SAX) interactions could be exploited, in addition, two of them had carbon microparticles embedded. All sorbents retained both acidic and basic compounds in the preliminary assays but only the basic compounds were retained selectively through ionic exchange interactions when a clean-up step was introduced. The SPE method was therefore optimized to promote the selective retention of the basic compounds, initially with the two best-performing sorbents. After optimization of the SPE protocol, these sorbents were evaluated for the analysis of environmental water samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method with the best-performing sorbent was then validated with 100 mL of river samples and 50 mL of effluent wastewater samples in terms of apparent recoveries (%R_app) spiking samples at 50 ng/L (river) and 200 ng/L (river and effluent), matrix effect, linear range, method quantification and detection limits, repeatability, and reproducibility. It should be highlighted that %R_app ranged from 40 to 85% and matrix effects ranged from -17 to -4% for spiked river samples. When the method was applied to river and effluent wastewater samples, most compounds were found in the range from 24 to 1233 ng/L with detection limits from 1 to 5 ng/L.

Nanomaterials with Excellent Adsorption Characteristics for Sample Pretreatment: A Review

Sample pretreatment in analytical chemistry is critical, and the selection of materials for sample pretreatment is a key factor for high enrichment ability, good practicality, and satisfactory recoveries. In this review, the recent progress of the sample pretreatment methods based on various nanomaterials (i.e., carbon nanomaterials, porous nanomaterials, and magnetic nanomaterials) with excellent adsorption efficiency, selectivity, and reproducibility, as well as their applications, are presented. Due to the unique nanoscale physical–chemical properties, magnetic nanomaterials have been used for the extraction of target analytes by easy-to-handle magnetic separation under a magnetic field, which can avoid cumbersome centrifugation and filtration steps. This review also highlights the preparation process and reaction mechanism of nanomaterials used in the sample pretreatment methods, which have been applied for the extraction organophosphorus pesticides, fluoroquinolone antibiotics, phenoxy carboxylic acids, tetracycline antibiotics, hazardous metal ions, and rosmarinic acid. In addition, the remaining challenges and future directions for nanomaterials used as sorbents in the sample pretreatment are discussed.

Synthesis of CoNi-layered double hydroxide on graphene oxide as adsorbent and construction of detection method for taste and odor compounds in smelling water

Taste and odor (T&O) compounds are important water pollutant, some of which are toxic. The relevant studies are all expand upon the well-known T&O compounds but for the unknown odors in smelling water. In this work, a method combining purge and trap with gas chromatograph-mass spectrometer (PT-GC/MS) and disperse solid-phase extraction with gas chromatograph (GC) was first proposed to detect T&O compounds in unknown odorous water accurately. Firstly, PT-GC/MS was used for a qualitative test on unknown odors in smelling water and determine the analytes. The hollow CoNi-layered double hydroxide (LDH) on graphene oxide (GO) was then used as a composite adsorbent to pretreat the water, in which the GO provided large specific surface, and the LDH worked as a confinement cavity to enhance capture and retention capacity for volatile organic compounds (VOCs). According to the properties of T&O compounds determined by PT-GC/MS in water, a corresponding GC method was established for accurately quantitative analysis. In this paper, five T&O compounds were detected simultaneously, including dimethyl sulfide, meistylene, N, N-dimethylbenzylamine, 2, 4-dimethylbenzaldehyde and 2, 4-di-tert-butylphenol. Extraction parameters were optimized, including ratio of desorption solvent, amount of adsorbent, pH value, etc. Under the optimal conditions, the detection limits for analysis were 1.14 μg/L to 3.07 mg/L. The satisfactory recoveries were 94-98%. Furthermore, two optimal determination outcomes of odor waters from different places support the practicability of the method, which is expected to be widely used in the detection of unknown odors in smelling water.

Molecularly imprinted wax

The development of an elution-free solid-phase extraction (SPE) process is of special interest in sample pretreatment. Due to the phase-change merits at relatively low temperatures and easy dissolution in n-hexane, wax spheres show great potential in this field. However, the conventional wax spheres possess a low affinity towards the target analytes when they are used as SPE adsorbents. In this study, using octadecanoic acid as the functional monomer and wax as the matrix, molecularly imprinted wax (MIW) spheres were successfully prepared. The obtained MIW spheres displayed remarkable molecular recognition ability and high selectivity towards the template. Interestingly, the as-synthesized molecularly imprinted wax (MIW) could be dissolved in n-hexane or melted by heating for subsequent fluorescence and mass spectrum analysis without the target elution process. Moreover, the melted MIW exhibited high repeatability, sensitivity and specificity for solid-state fluorescence detection. We believe that the imprinting method presented in this study will open a new window in analytical chemistry.

Dispersive solid phase extraction based on reduced graphene oxide modified Fe3O4 nanocomposite for trace determination of parabens in rock, soil, moss, seaweed, feces, and water samples from Horseshoe and Faure Islands

This study reports an efficient, green, sensitive and simple analytical protocol for trace determination of methyl paraben, ethyl paraben, propyl paraben, butylparaben and benzyl paraben by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The analytes were preconcentrated using an ultrasonication supported (US) dispersive solid phase extraction (DSPE) method based on reduced graphene oxide (rGO) modified iron nanoparticles (US-Fe₃O₄@rGO-DSPE). A reversed-phase C18 column and an isocratic elution program comprising of 20 mM phosphate buffer (pH 4.50) and acetonitrile(58:42, v/v) were used to elute and separate the analytes for detection. The limits of detection determined for the analytes were very low and were in the range of 0.02 - 0.16 ng mL^-1. The coefficients of determination obtained for the analytes ranged from 0.9973 to 0.9998, and this validated good linearity of the method.Percent relative standard deviations obtained in the range of 2.5 - 10.6% verified the method's high intraday repeatability. Accuracy of the proposed method was assessed with spiking experiments performed on complex sample matrices. Percent recoveries calculated for spiked soil, artificial seawater and seaweed samples were in acceptable ranges of 95 - 121%, 87 - 117% and 85 - 111%, respectively. These figures of merit suggest that HPLC-UV coupled with the US-Fe₃O₄@rGO-DSPEmethod is suitable for the determination of parabens in Antarctic samples.

Adsorption capacity of composite bio-modified geopolymer for multi-component heavy metal system: optimisation, equilibrium and kinetics study

Industrialisation and urbanisation contribute greatly to the deposition of toxic waste and metalloids to the environment. Therefore, the use of efficient and eco-friendly materials such as geopolymers and biopolymers is essential for the adsorption of the toxic metals. The implementation of these low-cost sorbents has fascinated a great deal of interest owing to effectiveness, ease of operation, less environmental impact, etc. In this study, biocomposites were synthesised from bio-treatment of geopolymer (kaolin and palm oil fuel ash) using an anionic biopolymer. The biocomposites were utilised as biosorbent for removal of Cu, Fe and Zn in a multi-component system, with the process parameters optimised. FTIR and SEM/EDX outcomes clearly denoted the microporous framework of geopolymer structures and the presence of bio-molecules from the biopolymer. XRD and XRF techniques on the precursors described suitability for geopolymerisation due to the rich aluminate-silicate content. Based on response surface methodology, the adsorption capacities for Cu, Fe and Zn are 35.01 mg/g, 45.175 mg/g and 44.630 mg/g at optimal conditions of pH (7.5), time (40.5 min), metal ion concentration (80 mg/l), biosorbent dosage (0.2 g) and biopolymer concentration (0.75 g in 50 ml). The multi-component system was apt with the modified competitive Langmuir isotherm which described the homogeneity of the prominent sites of the biocomposites. Based on the adsorption kinetics, Cu was only dominated by the pseudo-first-order reaction (PFOR) while Fe and Zn were influenced by both PFOR and intra-particle diffusion processes. The result obtained from the synthesised biocomposites recommends application to actual wastewater systems.

Development of dispersive solid-phase microextraction coupled with high-pressure liquid chromatography for the preconcentration and determination of the selected neonicotinoid insecticides

Neonicotinoid insecticides have raised a lot of societal concerns due to their environmental ubiquity and unique mode of action. Therefore, it is of great research interest to monitor their occurrence in the environmental waters. However, these compounds exist at low concentrations that is below instrument detection limits. This study reports the applicability of magnetic poly (3 aminobenzoic acid)-based activated carbon (Fe3O4@PABA/AC) composite as an adsorbent in dispersive magnetic solid-phase microextraction (d-MSPME) of neonicotinoid insecticides from wastewater and river water samples. The as-synthesized adsorbent was characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller and X-ray diffraction spectroscopy. The analytes of interest were detected and quantified by high-performance liquid chromatography coupled with diode array detector (HPLC–DAD). The parameters affecting the extraction and preconcentration processes, such as pH, extraction time, mass of adsorbent, desorption time and eluent volume, were optimized using fractional factorial design and central composite design. Under optimum conditions, the limits of detection and quantification were in the ranges of 0.41–0.82 µg L−1 and 1.4–2.7 µg L−1, respectively. The linearity ranged from 1.4–700 µg L−1 with correlation of determination (R2) values varied between 0.9933 and 0.9987. The intra-day and inter-day precisions were 0.35–0.75% and 1.7–5.5%, respectively. The spike recovery experiments were conducted to evaluate the accuracy of the d-MSPME analytical method in real samples, and the percentage recoveries ranged from 86.7 to 99.2%. Therefore, this method shows great potential applicability in preconcentrating the pollutants from the environment.

The Effect of the Synthesis Method on Physicochemical Properties of Selective Granular Polymer Sorbents

Investigation of the effect of the polymer synthesis method on physicochemical properties of sorbents is one of the topical problems in the chemistry of macromolecular compounds that has high scientific and practical interest. Determination of the optimal synthesis method will make it possible to create sorbents with physicochemical properties that led to the realization of effective sorption. In this work, we investigated the effect of synthesis methods (Pickering emulsion polymerization and precipitation polymerization in solution) of granular polymers based on 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate on physicochemical and sorption properties. The synthesis by Pickering emulsion polymerization led to improvement of the n-propyl alcohol diffusion into the polymer network and to the formation of more homogeneous and structurally stable polymer networks. Creating selective polymer networks by Pickering emulsion polymerization compared to precipitation polymerization in solution led to an increase in porosity, creation of more segregated surface of granules, improvement of binding sites availability at the temperature of 37 °C, and formation of the homogeneous sorption surface with high affinity to target molecules at 25 °C and 37 °C. Selective polymers synthesized by both polymerization methods had the largest values of available sorption surfaces areas for target molecules at 37 °C.

Stir bar sorptive-dispersive microextraction by a poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent for the determination of tricyclic antidepressants and their main active metabolites in human urine

A poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent was used for the rapid and sensitive determination of tricyclic antidepressants and their main active metabolites in human urine. This material was characterized by magnetism measurements, zeta potential, scanning electron microscopy, nitrogen adsorption-desorption isotherms, and thermogravimetric analysis. The proposed analytical method is based on stir bar sorptive-dispersive microextraction (SBSDME) followed by liquid chromatography-tandem mass spectrometry. The main parameters involved in the extraction step were optimized by using the response surface methodology as a multivariate optimization method, whereas a univariate approach was employed to study the desorption parameters. Under the optimized conditions, the proposed method was properly validated showing good linearity (at least up to 50 ng mL-1) and enrichment factors (13-22), limits of detection and quantification in the low ng L-1 range (1.4-7.0 ng L-1), and good intra- and inter-day repeatability (relative standard deviations below 15%). Matrix effects were observed for the direct analysis of urine samples, but they were negligible when a 1:1 v/v dilution with deionized water was performed. Finally, the method was successfully applied to human urine samples from three volunteers, one of them consuming a prescribed drug for depression that tested positive for clomipramine and its main active metabolite. Quantitative relative recoveries (80-113%) were obtained by external calibration. The present work expands the applicability of the SBSDME to new analytes and new types of magnetic sorbents.