Subcritical water extraction combined with molecular imprinting technology for sample preparation in the detection of triazine herbicides

Evaluation of deep eutectic solvents in the synthesis of molecularly imprinted fibers for the solid-phase microextraction of triazines in soil samples

Nowadays, molecularly imprinted polymers (MIPs) are well established and are considered excellent materials for performing selective extractions. However, with the progressive implementation of the principles of green chemistry, it is necessary to find greener alternatives for both the synthesis and further use of MIPs in sample preparation. Accordingly, in the present work, different deep eutectic solvents (DES, both hydrophilic and hydrophobic), as an alternative to conventional organic solvents (i.e., toluene), were evaluated as porogens for the synthesis of imprinted fibers (monoliths), using fused silica capillaries as molds, for solid-phase microextraction (SPME). From this study, the polymer prepared with propazine (dummy template), methacrylic acid (monomer), ethylene glycol dimethacrylate (cross-linker), and a formic acid:L-menthol (1:1) DES (porogen) showed the best performance for selective rebinding of triazines. After optimization of the different variables involved in SPME, the new imprinted fibers were successfully applied to the extraction of target analytes (desisopropylatrazine, desethylatrazine, simazine, and atrazine) from soil sample extracts, providing relative recoveries ranging from 75.7 to 120.1%, reaching limits of detection within the range of 6.2-15.7 ng g-1, depending upon the analyte.

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.

A Review: Subcritical Water Extraction of Organic Pollutants from Environmental Matrices

Most organic pollutants are serious environmental concerns globally due to their resistance to biological, chemical, and photolytic degradation. The vast array of uses of organic compounds in daily life causes a massive annual release of these substances into the air, water, and soil. Typical examples of these substances include pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Since they are persistent and hazardous in the environment, as well as bio-accumulative, sensitive and efficient extraction and detection techniques are required to estimate the level of pollution and assess the ecological consequences. A wide variety of extraction methods, including pressurized liquid extraction, microwave-assisted extraction, supercritical fluid extraction, and subcritical water extraction, have been recently used for the extraction of organic pollutants from the environment. However, subcritical water has proven to be the most effective approach for the extraction of a wide range of organic pollutants from the environment. In this review article, we provide a brief overview of the subcritical water extraction technique and its application to the extraction of PAHs, PCBs, pesticides, pharmaceuticals, and others form environmental matrices. Furthermore, we briefly discuss the influence of key extraction parameters, such as extraction time, pressure, and temperature, on extraction efficiency and recovery.

Micro-matrix cartridge extraction followed by online micro-solid phase extraction based on polystyrene@hydroxypropyl-β-cyclodextrin nanofibers for selective determination of fipronil and its metabolites in soil

Micro-matrix cartridge extraction coupled on-line to micro-solid phase extraction-high performance liquid chromatography-mass spectrometry (μ-MCE-online-μ-SPE-HPLC-MS) is presented. Micro-matrix cartridge extraction (μ-MCE) was applied to highly efficient desorption of adsorbed pesticides from contaminated soil with favorable extraction efficiency (100%). Novel polystyrene@hydroxypropyl-β-cyclodextrin (PS@HPCD) electrospun nanofibers with 3D network structure were prepared to selectively capture fipronil and its metabolites. High selectivity was obtained with adsorption efficiency ≥ 86.64% via complexation, hydrophobic affinity, and π-π interactions. PS@HPCD nanofibers exhibited remarkable advantages such as excellent enrichment factors (24-55), superior permeability, and long service life (> 65 times). Under the optimum conditions, wide linear range (0.1-1000 ng g^-1), low detection limits (0.0032-0.0067 ng g^-1), high recoveries (84-124.5%), favorable repeatability (RSD ≤ 10.4%, n = 5), and reproducibility (RSD ≤ 7.2%, n = 3) were acquired for fipronil and three metabolites. The developed method was applied to the pesticide determination in actual soils and the ISO-certified soil with satisfactory recoveries (96.5%). The method developed provides a green, efficient, and miniaturized method for the determination of trace pesticide residues in soil.

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.

Green Extraction Techniques as Advanced Sample Preparation Approaches in Biological, Food, and Environmental Matrices: A Review

Green extraction techniques (GreETs) emerged in the last decade as greener and sustainable alternatives to classical sample preparation procedures aiming to improve the selectivity and sensitivity of analytical methods, simultaneously reducing the deleterious side effects of classical extraction techniques (CETs) for both the operator and the environment. The implementation of improved processes that overcome the main constraints of classical methods in terms of efficiency and ability to minimize or eliminate the use and generation of harmful substances will promote more efficient use of energy and resources in close association with the principles supporting the concept of green chemistry. The current review aims to update the state of the art of some cutting-edge GreETs developed and implemented in recent years focusing on the improvement of the main analytical features, practical aspects, and relevant applications in the biological, food, and environmental fields. Approaches to improve and accelerate the extraction efficiency and to lower solvent consumption, including sorbent-based techniques, such as solid-phase microextraction (SPME) and fabric-phase sorbent extraction (FPSE), and solvent-based techniques (μQuEChERS; micro quick, easy, cheap, effective, rugged, and safe), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), in addition to supercritical fluid extraction (SFE) and pressurized solvent extraction (PSE), are highlighted.

Dummy molecularly imprinted polymers for class-selective extraction of amphetamine-type stimulants from alcoholic and nonalcoholic beverages

Molecularly imprinted polymer was constructed for the first time through dummy imprinting strategy with homopiperonylamine as dummy template. The prepared dummy molecularly imprinted polymer (DMIP) showed high class selectivity towards the most popular amphetamine-type stimulants (ATSs) such as methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxy-amphetamine, and 3,4-methylenedioxy-N-ethylamphetamine with the imprinting factors of 2.280∼3.698 and selectivity factors of 1.654∼3.698. Moreover, ATSs could be rapidly adsorbed from water with the equilibrium time within 5 min. Hydrogen-bonding interaction between the amino groups of ATSs and carboxy on DMIP could be dominated adsorption mechanism. DMIP was employed as solid phase extraction (SPE) sorbents. Under the optimum extraction conditions, the method using DMIP-based SPE and high performance liquid chromatography-tandem mass spectrometry showed good linearity in the range of 0.025∼1.00 μmol L^-1, good repeatability (RSD 4.8∼8.6%, n = 5) and low limits of quantification (0.007∼0.200 ng mL^-1, S/N = 10). Satisfactory recoveries (72.5∼120%) with low RSD values (<10%) were obtained for all targets viz. spiked coke carbonated drinks, beer and cocktail. Compared with other commercial SPE sorbents, DMIP exhibited lower matrix effect (ME) for coke, beer and cocktail with ME values of 101∼124%, 75.8∼80.2% and 103∼128%, respectively. The obtained results suggested that the developed DMIP materials could be a potential candidate for pretreatment of ATSs in alcoholic and nonalcoholic beverages.

Applicability of Superheated Water Extraction for the Quantification of Pesticide Residues in Leafy Vegetables

Superheated water extraction (SWE) of pesticide residues in a cabbage sample was demonstrated. The recovery yields of several relatively polar pesticides (log P_ow < 3) by the spike-and-recovery method at 100°C were acceptable. Increasing the extraction temperature up to 150°C led to enhanced extraction efficiency except for pesticides that induced degradation. The recovery yields of some target pesticides having log P_ow values of 3.5 - 4 were effectively enhanced by increasing the number of extraction cycles. The observed concentration of fenitrothion in a cabbage sample was comparable with those by the official Japanese analytical method. These results suggested SWE is potentially suitable for the extraction of different relatively high-to-medium polarity pesticides.

Selective Adsorption and Purification of the Acteoside in Cistanche tubulosa by Molecularly Imprinted Polymers

Acteoside (ACT) is the main component of phenylethanoid glycosides in Cistanche tubulosa, and it is extremely desirable for obtaining high purification of ACT by molecularly imprinted polymers (MIPs) from their extracts. In this study, MIPs were designed and synthetized to adsorb selectively the ACT in C. tubulosa. The effects of different functional monomers, cross-linkers, and solvents of MIPs were investigated. MIPs were studied in terms of static adsorption experiments, dynamic adsorption experiments, and selectivity experiments. The optimal functional monomer, cross-linking agent, and solvent are 4-vinylpyridine, ethylene glycol dimethylacrylate, and the mixed solvent (acetonitrile and N,N-dimethylformamide, 1:1.5, v/v), respectively. Under the optimal conditions, the synthesized MIP1 has a high adsorption performance for ACT. The adsorption capacity of MIP1 to ACT reached 112.60 mg/g, and the separation factor of ACT/echinacoside was 4.68. Because the molecularly imprinted cavities of MIP1 resulted from template molecules of ACT, it enables MIP1 to recognize selectively ACT. Moreover, the N–H groups on MIP1 can form hydrogen bonds with the hydroxyl groups on the ACT; this improves the separation factor of MIP1. The dynamic adsorption of ACT accorded with the quasi-second-order kinetics; it indicated that the adsorption process of MIP1 is the process of chemical adsorption to ACT. MIPs can be applied as a potential adsorption material to purify the active ingredients of herbal medicines.

A disposable electrochemical sensor based on electrospinning of molecularly imprinted nanohybrid films for highly sensitive determination of the organotin acaricide cyhexatin

Nanofibrous polyporous membranes imprinted with cyhexatin (CYT) were formed via the ordered distribution of the imprints in electrospun nanofibers. The MIPs have a high mass transfer rate and enhanced adsorption capacity. In addition, a printed carbon electrode with enhanced sensitivity was developed via electrochemical fabrication of reduced graphene oxide (rGO) and gold nanoparticles (AuNPs). The molecularly imprinted sensor exhibits excellent selectivity and sensitivity for CYT. The structure and morphology of the nanohybrid films were characterized by using scanning electron microscopy, atomic force microscopy and chronoamperometry. The sensing performances were evaluated by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy by using hexacyanoferrate(IV) as an electrochemical probe. The electrode, best operated at a working potential of around 0.16 V (vs. Ag/AgCl), has a linear response in the 1-800 ng mL^-1 CYT concentration range and a detection limit of 0.17 ng mL^-1 (at S/N = 3). The sensor demonstrated satisfactory recoveries when applied to the determination of CYT in spiked pear samples. Graphical abstract Schematic presentation of the electrochemical sensor for detection of CYT.

A magnetic graphene-like MoS2 nanocomposite for simultaneous preconcentration of multi-residue herbicides prior to UHPLC with ion trap mass spectrometric detection

A magnetic graphene-like molybdenum disulfide nanocomposite was prepared by liquid-phase exfoliation and hydrothermal synthesis. The morphology, structure, and magnetic behavior of the nanocomposite were characterized by X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis, vibrating sample magnetometry, scanning electron microscopy and transmission electron microscopy. The nanocomposite was employed as a sorbent for magnetic solid-phase extraction (MSPE) of eight triazine and ten sulfonylurea herbicides from environmental water and corn samples. Specifically, this was studied with cyanazine, simetryn, atrazine, methoprotryne, ametryn, prometryn, terbutryn, dipropetryn, metsulfuron-methyl, sulfometuron-methyl, amidosulfuron, rimsulfuron, nicosulfuron, bensulfuron-methyl, halosulfuron-methyl, pyrazosulfuron-ethyl, chlorimuron-ethyl, and cyclosulfamuron. The parameters affecting extraction efficiency (sorbent amount, pH value of the sample, extraction and elution conditions) were studied and optimized. Following MSPE, the multi-residue herbicides were quantified by ultra-high performance liquid chromatography combined with ion trap mass spectrometry and electrospray ionization. The limits of detection range between 20 and 170 ng·L^-1. The extraction recoveries of eighteen herbicides from corn samples were in the range between of 64.7% and 103.1%, with RSDs of <17.6%. Graphical abstract Schematic presentation of magnetic graphene-like MoS₂ nanocomposite as an absorbent for simultaneous preconcentration of eight triazine and ten sulfonylurea herbicides in corn and water prior to ultra-high performance liquid chromatography (UHPLC) with ion trap mass spectrometry detection.

Dual-template imprinted polymers for class-selective solid-phase extraction of seventeen triazine herbicides and metabolites in agro-products

A novel dual-template molecularly imprinted polymer (DMIP) was prepared with atrazine and prometryn as the template and applied as a class-specific adsorbent for simultaneously selective solid-phase extraction of seventeen triazine herbicides and metabolites from complex matrices. For comparison, a non-imprinted polymer (NIP) and two single-template imprinted polymers (SMIPs) were also synthesized using the same procedure of DMIP, but in the absence of the template (NIP) or with one template (SMIP). Various parameters affecting the extraction performance of DMIP-SPE were investigated in detail. Under the optimum conditions, the enrichment efficiency, class-selectivity and reusability of DMIP-SPE were evaluated. Only DMIP-SPE possessed high affinity and good selective recognition ability for all the seventeen targets including chloro-, thiomethyl- and methoxy- triazines. Further, a DMIP-SPE-LC-MS/MS method was developed for simultaneously determining trace triazine herbicides and metabolites in maize, wheat and cottonseed samples. The method showed good linearity (r>0.9941) in the range of 10-200 μg kg^-1, high sensitivity with low limits of detection of 0.5-8.8 μg kg^-1, and satisfactory recoveries of 61.3-105.9% with relative standard deviations of 2.1-10.7%. These results highlighted the good application prospect of the multi/dual-template imprinting strategy in the high-throughput analysis of various concerned contaminants in agro-products.