Simultaneous determination of levofloxacin and ciprofloxacin in human urine by ionic-liquid-based, dual-template molecularly imprinted coated graphene oxide monolithic solid-phase extraction

Dual-Functional Monomer MIPs and Their Comparison to Mono-Functional Monomer MIPs for SPE and as Sensors

A molecularly imprinted polymer (MIP) is a synthetic polymer that has characteristics such as natural receptors which are able to interact and bind to a specific molecule that is used as a template in the MIP polymerization process. MIPs have been widely developed because of the need for more selective, effective, and efficient methods for sample preparation, identification, isolation, and separation. The MIP compositions consist of a template, monomer, crosslinker, initiator, and porogenic solvent. Generally, MIPs are only synthesized using one type of monomer (mono-functional monomer); however, along with the development of MIPs, MIPs began to be synthesized using two types of monomers to improve the performance of MIPs. MIPs used for identification, separation, and molecular analysis have the most applications in solid-phase extraction (SPE) and as biochemical sensors. Until now, no review article has discussed the various studies carried out in recent years in relation to the synthesis of dual-functional monomer MIPs. This review is necessary, as an improvement in the performance of MIPs still needs to be explored, and a dual-functional monomer strategy is one way of overcoming the current performance limitations. In this review article, we discuss the techniques commonly used in the synthesis of dual-functional monomer MIPs, and the use of dual-functional monomer MIPs as sorbents in the MI-SPE method and as detection elements in biochemical sensors. The application of dual-functional monomer MIPs showed better selectivity and adsorption capacity in these areas when compared to mono-functional monomer MIPs. However, the combination of functional monomers must be selected properly, in order to achieve an effective synergistic effect and produce the ideal MIP characteristics. Therefore, studies regarding the synergistic effect of the MIP combination still need to be carried out to obtain MIPs with superior characteristics.

Functionalized monolithic columns: Recent advancements and their applications for high-efficiency separation and enrichment in food and medicine

The chromatographic column is the core of a high-performance liquid chromatography (HPLC) system, and must have excellent separation efficiency and selectivity. Therefore, functional modification materials for monolithic columns have been rapidly developed. This study is a systematic review of the recently reported functionalized monolithic columns. In particular, the study reviews the types of functional monomers under different modification conditions, as well as the separation and detection techniques combined with chromatography, and their development prospects. In addition, the applications of functionalized monolithic columns in food analysis, biomedicine, and the analysis of active ingredient of Chinese herbal medicines in recent years are also discussed. Also reviewed are the functionalized monolithic columns for qualitative and quantitative analysis. It provided a reference for further development and application of organic polymer monolithic columns.

Antioxidant analysis of ultra-fast selectively recovered 4-hydroxy benzoic acid from fruits and vegetable peel waste using graphene oxide based molecularly imprinted composite

Food processing industries generate 25-30% of fruit and vegetable peel (F&VP) waste of the total produce, which are rich in polyphenolic antioxidants (PA). Sustainable solution for the above waste can be its valorization for the recovery of PA, often used as natural preservative. Present work reports rationally designed graphene oxide-based molecularly imprinted composites (GOMIPs) using ionic liquid 1-allyl-3-octylimidazolium chloride (A) as a green functional monomer for selective recovery of PA 4-Hydroxy benzoic acid (4HA) from F&VP/pomegranate peel (PGP) waste. GOMIP-A and GOMIP-V were characterized using various techniques for its successful synthesis. GOMIP-A attained equilibrium within 10 min with adsorption capacity of 190.56 μmol g-1 for 4HA. Developed HPLC method depicted selective recovery of 77.23% and 62.83% 4HA from F&VP and PGP waste respectively by GOMIP-A. Subsequently, desorbed 4HA from GOMIP-A matrices exhibited the antioxidant potential of 33.53% (F&VP extract) and 47.97% (PGP extract) for DPPH radical.

Co-precipitation polymerization of dual functional monomers and polystyrene-co-divinylbenzene for ciprofloxacin imprinted polymer preparation

Novel ciprofloxacin composite imprinted materials are synthesized by using co-precipitation polymerization of dual functional monomers (methacrylic acid and 2-vinylpyridine) and polystyrene-co-divinylbenzene. The intermolecular interactions between monomers and template are evaluated by molecular modeling analysis. The physicochemical properties of the obtained polymers are characterized using FT-IR, TGA, and SEM. Batch adsorption experiments are used to investigate adsorption properties (kinetic, pH, and isotherm). These polymers are employed to prepare the solid phase extraction cartridges, and their extraction performances are analyzed by the HPLC-UV method. DFT calculations indicate that hydrogen bonding and π−π stacking are the driving forces for the formation of selective rebinding sites. The obtained polymers exhibit excellent adsorption properties, including fast kinetics and high adsorption capacity (up to 10.28 mg g⁻¹) with an imprinted factor of 2.55. The Scatchard analysis indicates the presence of specific high-affinity adsorption sites on the imprinted polymer. These absorbents are employed to extract CIP in river water with recoveries in the range of 65.97–119.26% and the relative standard deviation of 3.59–14.01%. Furthermore, the used cartridges could be reused at least eight times without decreasing their initial adsorption capacity.

Ciprofloxacin imprinted polymers were prepared using co-precipitation polymerization of methacrylic acid, 2-vinylpyridine and polystyrene-co-divinylbenzene.

Synergetic Effect of Dual Functional Monomers in Molecularly Imprinted Polymer Preparation for Selective Solid Phase Extraction of Ciprofloxacin

BACKGROUND

Ciprofloxacin (CIP), an important broad-spectrum fluoroquinolone antibiotic, was often used as a template molecule for the preparation of imprinted materials. In this study, methacrylic acid and 2-vinylpyridine were employed for the first time as dual functional monomers for synthesizing ciprofloxacin imprinted polymers.

METHODS

The chemical and physicochemical properties of synthesized polymers were characterized using Fourier transform-infrared spectroscopy, thermogravimetric analysis-differential scanning calorimetry, scanning electron microscopy, and nitrogen adsorption-desorption isotherm. The adsorption properties of ciprofloxacin onto synthesized polymers were determined by batch experiments. The extraction performances were studied using the solid phase extraction and HPLC-UV method.

RESULTS

The molecularly imprinted polymer synthesized with dual functional monomers showed a higher adsorption capacity and selectivity toward the template molecule. The adsorbed amounts of ciprofloxacin onto the imprinted and non-imprinted polymer were 2.40 and 1.45 mg g-1, respectively. Furthermore, the imprinted polymers were employed as a selective adsorbent for the solid phase extraction of ciprofloxacin in aqueous solutions with the recovery of 105% and relative standard deviation of 7.9%. This work provides an alternative approach for designing a new adsorbent with high adsorption capacity and good extraction performance for highly polar template molecules.

Molecularly imprinted solid-phase extraction of Chikusetsu saponin IVa from Panacis majoris Rhizoma

As the main active component of Panacis majoris Rhizoma, Chikusetsu saponin IVa has the activity of anti-oxidation, anti-inflammatory pain, and so on. Obtaining high purity Chikusetsu saponin IVa by simple purification steps is a prerequisite for its deep development. In this paper, the separation and purification of Chikusetsu saponin IVa were studied by molecular imprinting technique. By ultraviolet and visible spectrophotometry and computer molecular simulation, it was concluded that water-soluble 3-(2-carboxyethyl)-1-vinylimidazolium bromide ionic liquid was the best functional monomer compared with acrylic acid and acrylamide. The molecularly imprinted polymers were prepared by precipitation polymerization at 60℃ with Chikusetsu saponin IVa as template molecule, 3-(2-carboxyethyl)-1-vinylimidazolium bromide as functional monomer, ethylene glycol dimethacrylate as cross-linker, 2, 2'-azobisisobutyronitrile as initiator, and ethanol as porogen. The properties of molecularly imprinted polymers were studied by scanning electron microscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, nitrogen adsorption/desorption isotherm, and X-ray photoelectron spectroscopy. The maximum adsorption capacity was 171.33 mg/g, and the imprinting factor was 2.6. Finally, the polymers can be successfully used in the purification of Chikusetsu saponin IVa from Panacis majoris Rhizoma through a simple procedure, the content was significantly increased. The recoveries of the spiked samples for the CS-IVa ranged from 94.05 to 99.95% with relative standard deviation values lower than 2.67%. The results showed that the polymers demonstrated good adsorption capacity for Chikusetsu saponin IVa. Meanwhile, the polymers showed great stability and reusability during the application.

Hydrophilic deep eutectic solvents modified phenolic resin as tailored adsorbent for the extraction and determination of levofloxacin and ciprofloxacin from milk

A reliable and efficient method for the simultaneous extraction and determination of antibiotics of ciprofloxacin and levofloxacin from milk was developed with solid phase extraction based on tailored adsorbent materials of deep eutectic solvents modified phenolic resin (DES-R-SPE). Six types of polyhydric alcohol-based hydrophilic DESs were prepared to modify the phenolic resin with the compositions of 3-aminophenol as a functional monomer, glyoxylic acid as a crosslinker, and polyethylene glycol 6000 as a porogen. And the prepared DES-Rs showed better extraction capacities for the target analytes than the unmodified phenolic resin because of more hydrogen bonding and electrostatic interactions supplied by DESs. The choline chloride-glycerol-based resin (DES¹-R) with the highest adsorption amounts was selected and the adsorption behavior of it was studied with static adsorption and the dynamic adsorption performance; the adsorption process followed Freundlich isotherm (R² ≥ 0.9337) and pseudo-second-order (R² ≥ 0.9951). The present DES¹-R-SPE method showed good linear range from 0.5 to100 μg mL^-1 (R² ≥ 0.9998), good recoveries of spiked milk samples (LEV, 96.7%; CIP, 101.5%), and satisfied repeatability for intra-day and inter-day (LEV, RSD≤5.4%; CIP, RSD≤4.6%).

[Research progress in application of immobilized ionic liquid materials to separation by solid-phase extraction]

Ionic liquids are low-temperature molten salts with almost no vapor pressure, and they are composed of organic cations and inorganic anions. Ionic liquids are characterized by the properties of good chemical stability, high solubility, designable structure, high conductivity and so on. The physicochemical properties of an ionic liquid depend on the nature and size of the cation and anion, which confer unique characteristics; hence, these reagents are also termed "designed extractants." As a new class of green solvents, ionic liquids are potential replacements to traditional volatile organic solvents used for extraction; for this reason, ionic liquids have attracted the attention of scientists. Research on the methods of preparation and applications of ionic liquids is being diversified, and they are extensively used in catalytic chemistry, photoelectron chemistry, materials chemistry, analytical chemistry, etc. By functional guiding design, the structures of ionic liquids, especially the imidazole ring cations, can be easily grafted with active groups such as hydroxyl, amino, carboxyl, and cyano groups, so that interactions between the ionic liquids and target molecules can be promoted via the formation of π-π bonds, hydrogen bonds, ionic bonds, and van der Waals forces. In addition, ionic liquids can be readily immobilized on solid carriers by physical or chemical means in order to obtain a new solid material with ionic liquids embedded internally or decorated on the surface. Furthermore, ionic liquids could be converted into ionic liquid-immobilized composite materials by impregnation, grafting, etc. The resulting composites not only suffer minimal loss of ionic liquids but also retain the typical characteristics of the ionic liquids and solid materials, thus showing improved mass transfer performance and better adsorption performance. Immobilized materials are characterized by high enrichment efficiency, high adsorption capacity, good stability, and strong extraction selectivity, as well as the presence of numerous recognition sites and high utilization rate of ionic liquids. In recent years, they have been widely used as solid-phase extraction adsorption materials for the separation of small organic molecules. This review introduces common immobilization methods and the characteristics of ionic liquid-immobilized materials, as well as their application in solid-phase extraction. In this paper, methods for the immobilization of ionic liquids with solid carriers such as silica gel, molecular sieves, molecularly imprinted polymers, graphene oxide, and magnetic nanomaterials are summarized, and the application of ionic liquid-immobilized materials in solid-phase extraction is reviewed. The target substances include alkaloids, flavonoids, polyphenols, and other natural active components as well as common drug molecules, organic pesticides, and other organic small molecular compounds. The properties, applications, and separation mechanisms of ionic liquids immobilized with various carriers are systematically introduced. Literature survey shows that the distribution of the binding active sites of ionic liquid-immobilized materials to the target molecules is more uniform, which increases the adsorption capacity of the materials. The adsorption efficiency of ionic liquid-immobilized materials is related to the type of ionic liquid, amount of adsorption material, concentration of the sample solution, adsorption temperature, solution pH, flow rate of the eluent, and type and amount of the eluting solvent. The existing disadvantages of ionic liquids, such as simple structures, insufficient basic theoretical research, and unsatisfactory extraction degree in complex matrixes would also be discussed. The corresponding solutions would be presented with the aim of providing guidance for the application of ionic liquid-immobilized materials in the separation and analysis of targets in complex matrices, thus paving the way for a new direction in the field of extraction and separation.

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.

Role of Ionic Liquids in Composites in Analytical Sample Preparation

Ionic liquids (ILs) are a group of non-conventional salts with melting points below 100 °C. Apart from their negligible vapor pressure at room temperature, high thermal stability, and impressive solvation properties, ILs are characterized by their tunability. Given such nearly infinite combinations of cations and anions, and the easy modification of their structures, ILs with specific properties can be synthesized. These characteristics have attracted attention regarding their use as extraction phases in analytical sample preparation methods, particularly in liquid-phase extraction methods. Given the liquid nature of most common ILs, their incorporation in analytical sample preparation methods using solid sorbents requires the preparation of solid derivatives, such as polymeric ILs, or the combination of ILs with other materials to prepare solid IL-based composites. In this sense, many solid composites based on ILs have been prepared with improved features, including magnetic particles, carbonaceous materials, polymers, silica materials, and metal-organic frameworks, as additional materials forming the composites. This review aims to give an overview on the preparation and applications of IL-based composites in analytical sample preparation in the period 2017–2020, paying attention to the role of the IL material in those composites to understand the effect of the individual components in the sorbent.

The Influence of Ionic Liquids on the Effectiveness of Analytical Methods Used in the Monitoring of Human and Veterinary Pharmaceuticals in Biological and Environmental Samples-Trends and Perspectives

Recent years have seen the increased utilization of ionic liquids (ILs) in the development and optimization of analytical methods. Their unique and eco-friendly properties and the ability to modify their structure allows them to be useful both at the sample preparation stage and at the separation stage of the analytes. The use of ILs for the analysis of pharmaceuticals seems particularly interesting because of their systematic delivery to the environment. Nowadays, they are commonly detected in many countries at very low concentration levels. However, due to their specific physiological activity, pharmaceuticals are responsible for bioaccumulation and toxic effects in aquatic and terrestrial ecosystems as well as possibly upsetting the body's equilibrium, leading to the dangerous phenomenon of drug resistance. This review will provide a comprehensive summary of the use of ILs in various sample preparation procedures and separation methods for the determination of pharmaceuticals in environmental and biological matrices based on liquid-based chromatography (LC, SFC, TLC), gas chromatography (GC) and electromigration techniques (e.g., capillary electrophoresis (CE)). Moreover, the advantages and disadvantages of ILs, which can appear during extraction and separation, will be presented and attention will be given to the criteria to be followed during the selection of ILs for specific applications.

Determination of trace hydroxyl polycyclic aromatic hydrocarbons in urine using graphene oxide incorporated monolith solid-phase extraction coupled with LC-MS/MS

The biomonitoring of hydroxy polycyclic aromatic hydrocarbons in urine, as a direct way to access multiple exposures to polycyclic aromatic hydrocarbons, has raised great concerns due to their increasing hazardous health effects on humans. Solid-phase extraction is an effective and useful technique to preconcentrate trace analytes from biological samples. Here, we report a novel solid-phase extraction method using a graphene oxide incorporated monolithic syringe for the determination of six hydroxy polycyclic aromatic hydrocarbons in urine coupled with liquid chromatography-tandem mass spectrometry. The effect of graphene oxide amount, washing solvent, eluting solvent, and its volume on the extraction performance were investigated. The fabricated monoliths gave higher adsorption efficiency and capacity than the neat polymer monolith and commercial C₁₈ sorbent. Under the optimum conditions, the developed method provided the detection limits (S/N = 3) of 0.02-0.1 ng/mL and the linear ranges of 0.1-1500 ng/mL for six analytes in urine sample. The recoveries at three spiked levels ranged from 77.5 to 97.1%. Besides, the intra column-to-column (n = 3) and inter batch-to-batch (n = 3) precisions were ≤ 9.8%. The developed method was successfully applied for the determination of hydroxy polycyclic aromatic hydrocarbons in urine samples of coke oven workers.