Dummy molecularly imprinted solid phase extraction of climbazole from environmental water samples

A solid phase extraction column based on SiO2@ZIF-8 for efficient analysis of domoic acid toxins in the seawater environment: experiments and DFT calculations on adsorption behaviour

Algal toxins are important metabolites of toxic harmful algal blooms (HABs), and their qualitative and qualitative detection can serve as early warning indicators for toxic HABs, complementing traditional HAB monitoring and improving the accuracy of early warning. Therefore, this work took the detection of domoic acid (DA) as an example and prepared zeolitic imidazolate framework-8 (ZIF-8) with high enrichment performance and high water stability and its core-shell composite material SiO2@ZIF-8 as an adsorbent filler. Density functional theory (DFT) calculations and interference experiments verified that Zn2+ on SiO2@ZIF-8 played a crucial role in enriching DA on SiO2@ZIF-8. By using it as a solid-phase extraction (SPE) filler, it showed excellent performance compared with other SPE columns (C18/HLB/SAX/ZIF-8). Therefore, the SiO2@ZIF-8 column was coupled to high-performance liquid chromatography-mass spectrometry (SPE-HPLC-MS/MS) to establish a highly sensitive detection method for algal toxins in seawater, which had a wide linear range (12.0-5000.0 ng L-1), good reproducibility (RSD) and low limit of detection (4.0 ng L-1), and realized the monitoring of trace DA in the Pingtan sea area of Fujian Province from 2021 to 2022. By comparing other HAB early warning indicators such as salinity and pH and combining them with the information released by the Fujian Provincial Ocean and Fisheries Bureau, the content of DA in seawater measured by the established SPE-HPLC-MS/MS method can provide reference information for HAB monitoring and early warning.

Recent Developments in the Detection of Organic Contaminants Using Molecularly Imprinted Polymers Combined with Various Analytical Techniques

Molecularly imprinted polymers (MIPs) encompass a diverse array of polymeric matrices that exhibit the unique capacity to selectively identify a designated template molecule through specific chemical moieties. Thanks to their pivotal attributes, including exceptional selectivity, extended shelf stability, and other distinct characteristics, this class of compounds has garnered interest in the development of highly responsive sensor systems. As a result, the incorporation of MIPs in crafting distinctive sensors and analytical procedures tailored for specific analytes across various domains has increasingly become a common practice within contemporary analytical chemistry. Furthermore, the range of polymers amenable to MIP formulation significantly influences the potential utilization of both conventional and innovative analytical methodologies. This versatility expands the array of possibilities in which MIP-based sensing can be employed in recognition systems. The following review summarizes the notable progress achieved within the preceding seven-year period in employing MIP-based sensing techniques for analyte determination.

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.

Combination of Screen-Printed Carbon Electrode and Molecularly Imprinted Polymers for the Selective Determination of Phenolic Compounds in Wine

Caffeic acid (CA) is an efficient antioxidant found in wine and in plants and can be extracted from the by-products of the food industry. A molecularly imprinted polymer specific to caffeic acid (CA-MIP) was prepared by radical polymerization using N-phenylacrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and azobisisobutyronitrile as the initiator, in the presence of CA as the template molecule. The rebinding activities between the polymers and CA were promoted by an indirect method and characterized by cyclic voltammetry (CV) using a screen-printed carbon electrode (SPCE). It is a fast method, which only requires simple and portable instrumentation. The polymer showed a high selectivity toward CA and a good repeatability. CA-MIP was then applied in wine samples spiked with CA, and the results were compared to those obtained by a chromatographic method. With a limit of detection of 0.06 mM in wine, the recovery values confirmed that the method is suitable for further applications.

Preparation of Molecularly Imprinted Polymer Microspheres for Selective Solid-Phase Extraction of Capecitabine in Urine Samples

Molecularly imprinted solid-phase extraction to treat biological samples has attracted considerable attention. Herein, molecularly imprinted polymer (MIP) microspheres with porous structures were prepared by a combined suspension-iniferter polymerization method using capecitabine (CAP) as a template molecule. This material was subsequently used as a solid-phase extraction agent to separate and enrich drug molecules in urine samples. UV analysis revealed that methacrylate (MAA) was an ideal functional monomer, and 1H Nuclear Magnetic Resonance (1H NMR), Ultraviolet (UV), and Fourier transform-infrared (FT-IR) spectroscopic analyses were used to study the interaction forces between MAA and CAP, demonstrating that hydrogen bonding was the primary interaction force. MIPs with outstanding selectivity were successfully prepared, and the analysis of their surface morphology and chemical structure revealed a spherical morphology with small holes distributed across a rough surface. This surface morphology significantly reduced the mass transfer resistance of template molecules, providing an ideal template recognition effect. Using the molecularly imprinted solid-phase extraction method, CAP and the structural analog cytidine (CYT) were pretreated in urine samples and quantified by HPLC. The results showed that CAP and CYT recoveries reached 97.2% and 39.8%, respectively, with a limit of detection of 10.0–50.0 µg·mL−1. This study provides a novel approach to drug molecule pretreatment that can be applied in drug separation and functional materials science fields.

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.

A miniaturized analytical method based on molecularly imprinted absorbents for selective extraction of (S)-1,1'-binaphthyl-2,2'-diamine and combinatorial screening of polymer precursors by computational simulation

Chiral resolution of binaphthylamine is often a toilful conundrum in the field of analytical chemistry and biomedicine. The work puts forward a selective, sensitive, and miniaturized analytical method based on molecularly imprinted polymers (MIPs) as adsorbent for miniaturized tip solid-phase extraction (MTSPE) in the separation of binaphthylamine enantiomer. This method combines the advantages of MIPs (high selectivity), MTSPE (low consumption), and high-performance liquid chromatography (HPLC, high sensitivity). A simple synthesis methodology of MIP (P2) was conducted through bulk polymerization with (S)-(-)-1,1'-binaphthyl-2,2'-diamine (S-DABN) as template together with methacrylic acid monomer, and ethylene glycol dimethacrylate as cross-linker in proper porogen, realizing a selective recognition and efficient enrichment for S-DABN. The method exhibited appreciable linearity (0.06-1.00 mg ml^-1 ), low quantification limit (0.056 mg ml^-1 ), good absolute recoveries (45.70%-69.29%), and high precision (relative standard deviations ≤ 3.54%), along with low consumption (0.50 ml sample solution and 25.0 mg adsorbent). Based on the density functional theory, computational simulation was used to make a preliminary prediction for rational design of MIPs and gave a reasonable elaboration involving the potential mechanism of templates interacting with functional monomers. The adsorption kinetics and thermodynamics were investigated to evaluate the recombination process of substrates. In addition, the selectivity of MIPs for S-DABN was obtained by MIP-MTSPE coupled with HPLC, which supports the feasibility of this convenient design process. The proposed method was employed for selective extraction of S-DABN and exhibited promising potential in the application of chiral analysis.

Theoretical design and preparation research of molecularly imprinted polymers for steviol glycosides

In this paper, a novel molecularly imprinted polymer (MIP) for specific adsorption of steviol glycosides was designed, and the imprinting mechanism of self-assembly system between template and monomers was clearly explored. Firstly, steviol (STE) was chosen as dummy template, and the density functional theory (DFT) at B3LYP/6-31 + G (d, p) level was used to select monomers, imprinting molar ratios, solvents, and cross-linking agents. The selectivity to five steviol glycosides was also calculated. Importantly, reduced density gradient (RDG) theory combined with atom in molecules (AIM) and infrared spectrum (IR) was applied to investigate the bonding situation and the nature of noncovalent interaction in self-assembly system. The theoretical designed results showed that the template which interacts with acrylic acid (AA) has the minimum binding energy, and the complex with the molar ratio of 1 : 4 has the most stable structure. Toluene (TL) and ethylene glycol dimethacrylate (EGDMA) were chosen as the optimal solvent and cross-linking agent, respectively. Five hydrogen bonds formed in the self-assembly system are the key forces at the adsorption sites of MIPs through the RDG and AIM analyses. The MIPs were synthesized by theoretical predictions, and the results showed that the maximum adsorption capacity towards dulcoside A is 26.17 mg/g. This work provided a theoretical direction and experimental validation for deeper researches of the MIPs for steviol glycosides. In addition, the method of RDG theory coupled with AIM and IR also could be used to analyze other imprinting formation mechanisms systematically.

The Importance of Developing Electrochemical Sensors Based on Molecularly Imprinted Polymers for a Rapid Detection of Antioxidants

This review aims to pin out the importance of developing a technique for rapid detection of antioxidants, based on molecular imprinting techniques. It covers three major areas that have made great progress over the years in the field of research, namely: antioxidants characterization, molecular imprinting and electrochemistry, alone or combined. It also reveals the importance of bringing these three areas together for a good evaluation of antioxidants in a simple or complex medium, based on selectivity and specificity. Although numerous studies have associated antioxidants with molecular imprinting, or antioxidants with electrochemistry, but even electrochemistry with molecular imprinting to valorize different compounds, the growing prominence of antioxidants in the food, medical, and paramedical sectors deserves to combine the three areas, which may lead to innovative industrial applications with satisfactory results for both manufacturers and consumers.

Exploration of a Molecularly Imprinted Polymer (MIPs) as an Adsorbent for the Enrichment of Trenbolone in Water

The presence of endocrine disruptors in surface waters can have negative implications on wildlife and humans both directly and indirectly. A molecularly imprinted polymer (MIP) was explored for its potential to enhance the UV-Vis determination of trenbolone in water using solid-phase extraction (SPE). The synthesized MIP was studied using Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM). Using the MIP resulted in a preconcentration and enrichment factor of 14 and 8, respectively. Trenbolone binding on the MIP was shown to follow a Langmuir adsorption and had a maximum adsorption capacity of 27.5 mg g−1. Interference studies showed that the MIP selectivity was not compromised by interferences in the sample. The MIP could be recycled three times before significant loss in analyte recovery.

Identification, quantification, and prioritization of new emerging pollutants in domestic and industrial effluents, Korea: Application of LC-HRMS based suspect and non-target screening

The present study was designed to identify recently (or rarely) recognized or unreported substances (RRS or URS) contained in the effluents from water treatment plants in two industrialized urban areas, Gumi and Daegu, in Korea. In addition to 30 initial targets, 72 substances were identified through suspect and non-target screening (SNTS). Among them were 4 RRSs and 22 URSs, respectively. The quantitative analyses were applied to 35 pharmaceuticals, 15 pesticides, 13 poly-/perfluorinated alkyl substances (PFASs), 2 organophosphate flame retardants (OPFRs), 2 corrosion inhibitors, and 3 metabolites. The highest average concentration was observed for benzotriazole, followed by those for niflumic acid, and metformin. Effluents from Gumi mainly contained benzotriazole and metformin whereas niflumic acid and tramadol were the major components in effluents from Daegu. According to a scoring system based on risk relevant parameters, higher priorities were given to telmisartan, PFOA, and cimetidine. Yet, priorities for some substances were area specific (e.g., benzotriazole from Gumi, PFASs from Daegu), reflecting differences in industry profiles and populations. Many of the RRSs and URSs were recognized as potential hazards. The new identifications and evaluations should be taken into consideration for constant monitoring and management, as do the previously recognized contaminants.

Recent advances and applications of molecularly imprinted polymers in solid-phase extraction for real sample analysis

Sample pretreatment is essential for the analysis of complicated real samples due to their complex matrices and low analyte concentrations. Among all sample pretreatment methods, solid-phase extraction is arguably the most frequently used one. However, the majority of available solid-phase extraction adsorbents suffer from limited selectivity. Molecularly imprinted polymers are a type of tailor-made artificial antibodies and receptors with specific recognition sites for target molecules. Using molecularly imprinted polymers instead of conventional adsorbents can greatly improve the selectivity of solid-phase extraction, and therefore molecularly imprinted polymer-based solid-phase extraction has been widely applied to separation, clean up and/or preconcentration of target analytes in various kinds of real samples. In this article, after a brief introduction, the recent developments and applications of molecularly imprinted polymer-based solid-phase extraction for determination of different analytes in complicated real samples during the 2015-2020 are reviewed systematically, including the solid-phase extraction modes, molecularly imprinted adsorbent types and their preparations, and the practical applications of solid-phase extraction to various real samples (environmental, food, biological, and pharmaceutical samples). Finally, the challenges and opportunities of using molecularly imprinted polymer-based solid-phase extraction for real sample analysis are discussed.

Microwave-assisted preparation of a molecularly imprinted monolith combining an imidazolium ionic liquid and POSS for enhanced extraction of baicalin-like compounds in Scutellaria baicalensis by means of in-capillary SPME followed by on-line LC and off-line LC-MS/MS

An imidazolium-type ionic liquid and polyhedral oligomeric silsesquioxane were combined to produce an imprinted monolith in capillary endowed with wide selectivity to enrich baicalin and its analogues for analysis by multidimensional LC systems.

Synthesis and characterization of phosphocholine chloride-based three-component deep eutectic solvent: application in dispersive liquid-liquid microextraction for determination of organothiophosphate pesticides

BACKGROUND

A new type of deep eutectic solvent based on three components using phosphate salts has been synthesized, characterized, and applied in the extraction of eight organothiophosphate pesticides from honey samples. In this study, the deep eutectic solvent was prepared from phosphocholine choline chloride as a hydrogen bond acceptor and dichloroacetic acid and decanoic acid as hydrogen bond donors. The method consisted of two steps in which initially the analytes were extracted from the samples into a water-miscible organic solvent. In the second step, the extracted phase was mixed with the prepared deep eutectic solvent and the mixture was used in the following dispersive liquid-liquid microextraction method.

RESULTS

The method was validated under optimal conditions, and it was found that it has low limits of detection (0.05-0.10 ng g^-1 ) and quantification (0.19-0.36 ng g^-1 ), good linearity (r²  ≥ 0.994), broad linearity (0.36-1000 ng g^-1 ), and satisfactory repeatability (relative standard deviation ≤10% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 2 ng g^-1 of each analyte).

CONCLUSION

The proposed method was applied in different honey samples, and malathion was found at a concentration of 29 ng g^-1 in one sample. © 2019 Society of Chemical Industry.

Zirconium metal-organic framework assisted miniaturized solid phase extraction of phenylurea herbicides in natural products by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

The zirconium metal-organic framework (Zr-MOF) was used as a novel and effective adsorbent material for the enrichment of five phenylurea herbicides (fenuron, monuron, diuron, linuron and pencycuron) in natural products. The target analytes were determined by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Some crucial experimental parameters, such as type of adsorbents, amount of adsorbent, type of eluent solvents and adsorption capacity were investigated and optimized. Under the optimum extraction conditions, the enrichment factors of fenuron, monuron, diuron, linuron and pencycuron were 90, 128, 148, 204 and 295 times, respectively. A good linearity was obtained in different concentration levels of target analytes with the determination coefficients (r²) larger than 0.993. In addition, the limits of detection varied from 0.05 to 0.36 ng/mL and the recoveries of the analytes were in the range of 85.19-99.13 %. The results demonstrated that the proposed miniaturized solid-phase extraction procedure coupled with Zr-MOF could become an effective tool to analyze phenylurea herbicides and would have the vast application prospect for the extraction of pesticide residue and more organic pollutants from Hawthorn, Dendrobii Officinalis Caulis and Salviae Miltiorrhizae Radix et Rhizoma samples.

Epitope-imprinted mesoporous silica nanoparticles for specific recognition of tyrosine phosphorylation

Tyrosine phosphorylation regulates the upstream signaling pathway but accounts for less than 0.1% of total phosphorylation in human cells. Herein, molecularly imprinted mesoporous materials were first synthesized to recognize the phosphorylated tyrosine residue from other phosphorylated residues.