Molecularly Imprinted Polymer Particles Research Articles

Malathion Detection Using Molecularly-Imprinted Polymer Quartz Crystal Microbalance Sensor

The extensive use of pesticides can result in overexposure and soil, water, and produce residues. For instance, residues of malathion were found on some vegetables. Molecularly-imprinted polymers (MIP) have been recently developed for sensing of pesticide residues. This study prepared malathion-imprinted polymers via precipitation polymerization and deposited on quartz crystal microbalance (QCM) electrodes. FTIR spectroscopy proved the incorporation and removal of malathion in the matrix of MIP. SEM images revealed that MIP particles are larger than the non-imprinted polymer (NIP) particles due to the incorporation of malathion. Binding experiments were done using standard malathion solutions of 10 to 60 ppm. The MIP-QCM sensor had a greater response than the NIP-QCM sensor. This is due to the specific binding sites in the MIP matrix. On the other hand, the response of NIP-QCM sensor is attributed to the non-specific adsorption sites in its matrix. A sensitivity and detection limit of 1.62 Hz·L/mg and 5.67 ppm, respectively were determined for the MIP-QCM sensor. Lastly, the MIP-QCM sensor is stable and reusable up to three (3) cycles.

Microwave‐assisted molecularly imprinted polymer synthesis for chemometric and rebinding mechanism of drug release applications

AbstractSynthesis of molecularly imprinted polymers (MIP) has gained wide interest as drug delivery vehicles in recent years. The conventional one‐variable‐at‐a‐time method for determining the best formulation ratio of MIP templates is resource‐ and time‐consuming. Thus, this study focused on the response surface methodology optimization of the best formulation for MIP preparation using methacrylic acid and divinylbenzene as functional monomer and cross‐linker, respectively. Two preparation systems were studied, namely microwave (MW)‐assisted and conventional synthesis. The MIPs showed spherical particles with smaller particle sizes (500 nm–1.45 μm) and higher yields (0.5–1.2 g) via MW‐assisted synthesis as compared to the conventional synthesis (size 660 nm–3.65 μm, yield 0.5–1.15 g). MW‐assisted synthesis is faster and more efficient to synthesize controlled shapes and sizes of MIP particles. The rebinding properties of prepared MIP via MW were higher (7.15 ± 0.02 mg/g) than conventional synthesis (3.00 ± 0.31 mg/g). The empirical models were developed to correlate the output response of rebinding properties and input variables. The analysis of variance confirmed that experimental data were superbly fitted to the proposed response models. A satisfactory correlation between the experimental and predicted values was obtained by both MIP prepared via MW‐assisted and conventional synthesis.

A molecularly imprinted polymer for microextraction by packed sorbent of sulfonylureas herbicides from corn samples

A molecularly imprinted polymer (MIP) was synthesized and assessed as a selective extraction phase in the microextraction by packed sorbent (MEPS) of sulfonylureas herbicides (SUHs) — Thifensulfuron, Chlorosulfuron, Tribenuron, and Bensulfuron — from grounded corn samples. Bensulfuron was employed as the template for the MIP preparation. MIP particles were chemically and structurally characterized. Distribution (Kd), selectivity (k), and relative selectivity (k') coefficients were estimated using binary mixtures of bensulfuron/betazon and bensulfuron/prometon. The most significant parameters affecting the MEPS performance were systematically studied in univariate and multivariate experiments. Analyses were performed by liquid chromatography coupled to time-of-flight mass spectrometry (LC-ToF). Under selected conditions, the developed MIP-MEPS-LC-ToF method demonstrated suitable analytical confidence and reliability. Determination coefficients (r2) higher than 0.9940, and limits of detection (LODs) of 2.5 µg kg-1 were obtained. Intra- and interday precision was lower than 14.2%, and accuracy ranged between 89.6% and 113.6%. The synthesized MIP demonstrated enhanced selectivity and higher SUHs uptake capability compared to the non-imprinted polymer (NIP) and tested commercial sorbents. Besides, the method is a cheap, feasible, and environmentally friendly analytical tool. A single MEPS device packed with 1.0 mg of MIP was reused more than 180 times without loss in its extraction capabilities.

Dipstick Sensor Based on Molecularly Imprinted Polymer‐Coated Screen‐Printed Electrodes for the Single‐Shot Detection of Glucose in Urine Samples—From Fundamental Study toward Point‐of‐Care Application

AbstractGlucose biosensors play an extremely important role in health care systems worldwide. Therefore, the field continues to attract significant attention leading to the development of innovative technologies. Due to their characteristics, Molecularly Imprinted Polymers (MIPs) represent a promising alternative to commercial enzymatic sensors. In this work, a low‐cost, flexible MIP‐based platform for glucose sensing by integrating MIP particles directly into screen‐printed electrodes (SPEs) is realized. The sensor design allows the detection of glucose via two different transducer principles, the so‐called “heat‐transfer method” (HTM) and electrochemical impedance spectroscopy (EIS). The sensitivity and selectivity of the sensor are demonstrated by comparing the responses obtained toward three different saccharides. Furthermore, the application potential of the MIP‐SPE sensor is demonstrated by analyzing the response in urine samples, showing a linear range of 14.38–330 µm with HTM and 1.37–330 µm with EIS. To bring the sensor closer to a real life application, a handheld dipstick sensor is developed, allowing the single‐shot detection of glucose in urine using EIS. This study illustrates that the simplicity of the dipstick readout coupled with the straightforward manufacturing process opens up the possibility for mass production, making this platform a very attractive alternative to commercial glucose sensors.

Direct analysis of tobacco specific nitrosamines in tobacco products using a molecularly imprinted polymer-packed column.

Tobacco specific nitrosamines (TSNAs) are highly carcinogenic by-products in tobacco samples, and their presence is regulated by the Food and Drug Administration. Molecularly imprinted polymers (MIPs) are synthetic polymers that have been "imprinted" with a template analyte in a co-polymer system, and can selectively extract analytes from complex matrices. MIPs can be incorporated into online systems, replacing traditional high performance liquid chromatography (HPLC) columns. MIP material specific for TSNAs was packed into an empty HPLC column using a slurry packing technique. The developed method with the MIP-packed HPLC column was validated on a LC-MS/MS system for the quantitation of N-nitrosonornicotine (NNN) and 4- (methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in commercial tobacco products. The method was linear over .1-10 ng/ml (.4-10 μg/g) for NNN and NNK. The limit of detection (LOD) was .03 ng/ml (12 μg/g) and the limit of quantitation (LOQ), .1 ng/ml (.4 μg/g). All column uniformity parameters with the exception of theoretical plate number were within the accepted criteria (% RSD values <15%). Theoretical plate number was <250, owing to the large (50 μm) sized MIP particles. Twenty-six tobacco products contained TSNA concentrations that were consistent with reported literature values. The TSNA-MIP based HPLC column effectively replaced a traditional reverse phase HPLC column, and was used for the direct analysis of nicotine and tobacco products without extensive sample preparation prior to instrumental analysis.

Thermal Pyocyanin Sensor Based on Molecularly Imprinted Polymers for the Indirect Detection of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a ubiquitous multi-drug-resistant bacterium, capable of causing serious illnesses and infections. This research focuses on the development of a thermal sensor for the indirect detection of P. aeruginosa infection using molecularly imprinted polymers (MIPs). This was achieved by developing MIPs for the detection of pyocyanin, the main toxin secreted by P. aeruginosa. To this end, phenazine was used as a dummy template, evaluating several polymeric compositions to achieve a selective MIP for pyocyanin recognition. The sensitivity of the synthesized MIPs was investigated by UV-vis analysis, with the best composition having a maximum rebinding capacity of 30 μmol g-1 and an imprinting factor (IF) of 1.59. Subsequently, the MIP particles were immobilized onto planar aluminum chips using an adhesive layer, to perform thermal resistance measurements at clinically relevant concentrations of pyocyanin (1.4-9.8 μM), achieving a limit of detection (LoD) of 0.347 ± 0.027 μM. The selectivity of the sensor was also scrutinized by subjecting the receptor to potential interferents. Furthermore, the rebinding was demonstrated in King's A medium, highlighting the potential of the sensor for the indirect detection of P. aeruginosa in complex fluids. The research culminates in the demonstration of the MIP-based sensor's applicability for clinical diagnosis. To achieve this goal, an experiment was performed in which the sensor was exposed to pyocyanin-spiked saliva samples, achieving a limit of detection of 0.569 ± 0.063 μM and demonstrating that this technology is suitable to detect the presence of the toxin even at the very first stage of its production.

A Molecularly Imprinted Polymer-Based Thermal Sensor for the Selective Detection of Melamine in Milk Samples.

In recent years, melamine-sensing technologies have increasingly gained attention, mainly due to the misuse of the molecule as an adulterant in milk and other foods. Molecularly imprinted polymers (MIPs) are ideal candidates for the recognition of melamine in real-life samples. The prepared MIP particles were incorporated into a thermally conductive layer via micro-contact deposition and its response towards melamine was analyzed using the heat-transfer method (HTM). The sensor displayed an excellent selectivity when analyzing the thermal response to other chemicals commonly found in foods, and its applicability in food safety was demonstrated after evaluation in untreated milk samples, demonstrating a limit of detection of 6.02 μM. As the EU/US melamine legal limit in milk of 2.5 mg/kg falls within the linear range of the sensor, it can offer an innovative solution for routine screening of milk samples in order to detect adulteration with melamine. The results shown in this work thus demonstrate the great potential of a low-cost thermal platform for the detection of food adulteration in complex matrices.

Facile Fabrication of Hollow Molecularly Imprinted Polymer Particles with Multicore Structure via Miniemulsion Polymerization

Facile Fabrication of Hollow Molecularly Imprinted Polymer Particles with Multicore Structure via Miniemulsion Polymerization

An ultra-sensitive and highly selective impedimetric sensor for vitamin D measurement based on a novel imprinted polymer synthesized utilizing template-derived functional monomer

A novel vitamin D3-imprinted (VD)-polymer was synthesized utilizing a functional monomer derived from vitamin D3. Acryloyl chloride reacted with VD leading to a functional monomer capable of interaction with VD during the molecularly imprinted polymer (MIP) synthesis step. Vitamin D3-derived functional monomer and divinylbenzene were copolymerized in the presence of vitamin D3 in order to create a new MIP, holding VD selective cavities, after template (VD) removal from the polymer. The MIP nanoparticles were used for the modification of a carbon paste electrode to fabricate VD selective sensor. The charge transfer resistance of Fe(CN)63-/Fe(CN)64−couple for the MIP-modified electrode increased significantly in the presence of VD; whereas, the non-imprinted polymer (NIP)-CPE electrode was not affected by VD, suggesting well acting of recognition sites of the MIP nanoparticles, incorporated into the electrode. The sensing mechanism was attributed to a gate effect principle. Interring of VD molecules to the selective sites of the MIP nanoparticles, existing on the electrode surface, makes the MIP particles swell and this leads to blocking the majority of routes via which the probe electroactive species accesses the carbon particles at the electrode surface. The MIP electrode was not sensitive to some molecules structurally similar to VD, suggesting a highly selective nature of the designed sensor. The new VD sensor impedimetric response as a function of the logarithm of VD concentration was found to be linear in the range of 1.0–100.0 pM. The detection limit of the sensor was estimated to be 0.22 pM. The sensor was used for VD level estimation in plasma samples.

Modern and Dedicated Methods for Producing Molecularly Imprinted Polymer Layers in Sensing Applications

Molecular imprinting (MI) is the most available and known method to produce artificial recognition sites, similar to antibodies, inside or at the surface of a polymeric material. For this reason, scholars all over the world have found MI appealing, thus developing, in this past period, various types of molecularly imprinted polymers (MIPs) that can be applied to a wide range of applications, including catalysis, separation sciences and monitoring/diagnostic devices for chemicals, biochemicals and pharmaceuticals. For instance, the advantages brought by the use of MIPs in the sensing and analytics field refer to higher selectivity, sensitivity and low detection limits, but also to higher chemical and thermal stability as well as reusability. In light of recent literature findings, this review presents both modern and dedicated methods applied to produce MIP layers that can be integrated with existent detection systems. In this respect, the following MI methods to produce sensing layers are presented and discussed: surface polymerization, electropolymerization, sol–gel derived techniques, phase inversionand deposition of electroactive pastes/inks that include MIP particles.

A highly sensitive plastic optic-fiber with a molecularly imprinted polymer coating for selective detection of 4-chlorophenol in water

To realize the selective detection of 4-chlorophenol (4-CP) in water, a highly sensitive plastic optical fiber (POF) evanescent wave sensor was prepared using a D-shaped POF coated selective adsorption film of 4-CP. The film was composed of molecularly imprinted polymer (MIP) particles and PEBA2533 matrix. The MIP particles were employed to realize the selective adsorption and enrichment of 4-CP molecules, which lead to the changes in the refractive index of the MIP-PEBA2533 coating. These, in turn, resulted in changes in the light transmission in the D-shaped region and caused the attenuation of the evanescent field intensity on the surface of the sensing region. To illustrate the measurement principle, a theoretical model of the sensor was established. Furthermore, the performance parameters of the sensors, such as sensitivity, repeatability, selectivity and low limit of detection (LOD), were experimentally studied. The results highlighted that the proposed sensor exhibited a good sensitivity of -0.56 × 10-6 (μg/L)-1 and LOD of 100 μg/L for the detection of 4-CP in water. Moreover, this optic-fiber sensor has high specific recognition ability for 4-CP. The results of this study could inform the development of methods for on-line and accurate detection of 4-CP.

Thermal Detection of Glucose in Urine Using a Molecularly Imprinted Polymer as a Recognition Element.

Glucose bio-sensing technologies have received increasing attention in the last few decades, primarily due to the fundamental role that glucose metabolism plays in diseases (e.g., diabetes). Molecularly imprinted polymers (MIPs) could offer an alternative means of analysis to a field that is traditionally dominated by enzyme-based devices, posing superior chemical stability, cost-effectiveness, and ease of fabrication. Their integration into sensing devices as recognition elements has been extensively studied with different readout methods such as quartz-crystal microbalance or impedance spectroscopy. In this work, a dummy imprinting approach is introduced, describing the synthesis and optimization of a MIP toward the sensing of glucose. Integration of this polymer into a thermally conductive receptor layer was achieved by micro-contact deposition. In essence, the MIP particles are pressed into a polyvinyl chloride adhesive layer using a polydimethylsiloxane stamp. The prepared layer is then evaluated with the so-called heat-transfer method, allowing the determination of the specificity and the sensitivity of the receptor layer. Furthermore, the selectivity was assessed by analyzing the thermal response after infusion with increasing concentrations of different saccharide analogues in phosphate-buffered saline (PBS). The obtained results show a linear range of the sensor of 0.0194–0.3300 mM for the detection of glucose in PBS. Finally, a potential application of the sensor was demonstrated by exposing the receptor layer to increasing concentrations of glucose in human urine samples, demonstrating a linear range of 0.0444–0.3300 mM. The results obtained in this paper highlight the applicability of the sensor both in terms of non-invasive glucose monitoring and for the analysis of food samples.

Encapsulation of Molecularly Imprinted Polymer Particles in Microcapsule by Facile Pickering Emulsion Polymerization

Encapsulation of Molecularly Imprinted Polymer Particles in Microcapsule by Facile Pickering Emulsion Polymerization

A rapid and sensitive method for separation of Cu2+ ions from industrial wastewater sample and water samples with methacrylamide-ethylene glycol dimethacrylate: A new synthesis of molecularly imprinted polymer.

In this study, new molecularly imprinted polymer particles (MIP) were synthesised to extract Cu2+ ions from aqueous solutions using radical polymerisation. MIP was developed using the methacrylamide‐ethylene glycol dimethacrylate (EGDMA) cross linking agent, methacrylamide monomer, and ACV initiator by the radical polymerisation method. A comparison of various cross linking agents in MIP production showed that the best cross linking agents are EGDMA and gallic acid. The template ions were removed by leaching with 0.100 M HCl. The polymer particles were characterised by FTIR spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The effect of different parameters such as cross linkers, pH, time, maximum adsorption capacity, and kinetic and isotherm adsorption were investigated. The best conditions were determined (pH = 8.0, t = 10 min, and q m = 262.53 mg g−1). The adsorption data were best fitted by Freundlich isotherm and pseudo second order kinetic models, as well. Due to its high adsorption capacity and multi‐layer behaviour, this method is an easy, fast and safe way to extract cations. Removal of Cu2+ in certified tap water and rain water was demonstrated and the industrial wastewater sample (Charmshahr, Iran) with which the MIP was developed using Methacrylamide‐ Ethylene Glycol Dimethacrylate (EGDMA) was good enough for Cu2+ determination in matrices containing components with similar chemical property such as Co2+, Zn2+, Fe2.

Colorimetric Sensing of Amoxicillin Facilitated by Molecularly Imprinted Polymers.

The scope of the presented research orientates itself towards the development of a Molecularly Imprinted Polymer (MIP)-based dye displacement assay for the colorimetric detection of the antibiotic amoxicillin in aqueous medium. With this in mind, the initial development of an MIP capable of such a task sets focus on monolithic bulk polymerization to assess monomer/crosslinker combinations that have potential towards the binding of amoxicillin. The best performing composition (based on specificity and binding capacity) is utilized in the synthesis of MIP particles by emulsion polymerization, yielding particles that prove to be more homogenous in size and morphology compared to that of the crushed monolithic MIP, which is an essential trait when it comes to the accuracy of the resulting assay. The specificity and selectivity of the emulsion MIP proceeds to be highlighted, demonstrating a higher affinity towards amoxicillin compared to other compounds of the aminopenicillin class (ampicillin and cloxacillin). Conversion of the polymeric receptor is then undertaken, identifying a suitable dye for the displacement assay by means of binding experiments with malachite green, crystal violet, and mordant orange. Once identified, the optimal dye is then loaded onto the synthetic receptor, and the displaceability of the dye deduced by means of a dose response experiment. Alongside the sensitivity, the selectivity of the assay is scrutinized against cloxacillin and ampicillin. Yielding a dye displacement assay that can be used (semi-)quantitatively in a rapid manner.

Synthesis of molecularly imprinted polymers using an amidine-functionalized initiator for carboxylic acid recognition

In traditional molecular imprinting reactions, the initial radicals generated by thermo- or photo-decomposition are randomly distributed in the reaction mixture. Because a noticeable portion of the initial radicals is able to cause self-polymerization of the crosslinking monomer, a significant part of the polymer product does not contain successfully imprinted molecular recognition sites. To solve this problem, we designed a molecular imprinting method using functionalized radical initiator to replace the conventional combination of initiator and functional monomer. Since the active radicals in the reaction mixture carry a template-binding moiety, the actual radical polymerization becomes more likely to take place nearby the molecular template. As a result, the efficiency of molecular imprinting can be improved. In this work, we report the use of amidine-functionalized initiator to synthesize molecularly imprinted polymers (MIPs) for selective recognition of methotrexate, a cytostatic drug used for cancer therapy. As glutamic acid represents a substructure of methotrexate, we select to use N-terminal protected glutamic acid as template to synthesize the MIPs. An initiator, 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) is used to provide strong interaction with the molecular template. Two MIPs synthesized using glutamic acid derivatives as templates display specific binding to the fluorescent amino acid derivative Fmoc-Glu. When the molecular binding is tested against methotrexate, the MIP particles also exhibit specific binding for the cytostatic drug. Using cationic functional initiator to target carboxyl epitope of molecular target, this work provides an additional example of molecular imprinting based on functionalized radical initiators.

Molecularly Imprinted Polymer Particles and Beads: A Survey of Modern Synthetic Techniques

Molecular imprinting technology is based on incorporating template molecules in the polymer matrix, followed by their extraction to leave specific cavities similar in shape and size to the incorporated template molecules. The resultant molecularly imprinted polymers (MIPs) then show antibody-like and enzyme-like behavior. MIPs are used as selective adsorbents, stationary phases, sensors, drug delivery agents, ultrafiltration systems, catalysts, etc. To achieve a specific function, MIPs are synthesized in various forms like beads, particles, membranes, fibers and composites. MIP beads and particles have prime importance due to their use in multiple applications. In this article, we present a survey of various polymerization techniques used for the synthesis of MIP beads and particles, along with a special focus on the studies presenting their use in separation and purification.

(Invited) Chemical Sensors Based on Thermal Resistance Analysis at Solid-Liquid Interfaces – Applications and Challenges

Introduction Over the past few decades, researchers have devoted considerable effort to the integration of synthetic receptors into chemical sensing platforms. In general, molecularly imprinted polymers (MIPs) have been developed for targets ranging from small molecules to proteins while surface imprinted polymers (SIPs) are generally used to detect larger entities such as microorganisms or whole cells [1]. These synthetic receptors have been combined with traditional electrochemical, optical or microgravimetric readout approaches to create sensors for various applications including medical diagnostics and environmental screening [2]. In 2012, a surprisingly versatile readout tool for label-free sensing was developed; the so-called heat-transfer method (HTM) [3]. The technique was originally developed for the detection of point mutations in DNA but was soon extended towards chemical sensing by coating the chips with synthetic receptors. In this way, it can be used for a wide variety of applications ranging from e.g. bacteria detection in urine samples for UTI diagnosis to cardiac biomarker testing in serum [4-5].The benefit of these thermal chemical sensing platforms over existing state-of-the-art technology lies in the unique combination of highly selective synthetic receptors and a low-cost, user-friendly readout platform that requires minimal instrumentation. The challenges towards commercial application mainly involve standardizing and upscaling the MIP/SIP synthesis procedure as well as the limited sensitivity of the readout approach. However, progress is being made in both aspects in recent years. Method Bacteria imprints were made by spin coating aluminum chips with semi-cured polyurethane layers. Template bacteria are immobilized onto a PDMS stamp and pressed into the polyurethane layer that was cured over-night. Removal of the stamp and template leads to a SIP containing microcavities that are complementary to the template. Thermal resistance over the solid-liquid interface was monitored by sending a thermal wave through the chip with an average temperature of 37.0°C and an amplitude of 0.1 °C. The phase shift of the transmitted thermal wave at 0.03 Hz was analyzed in function of the bacteria concentration in spiked urine samples [4]. MIPs can be made in a more reproducible manner than SIPs, through the so-called solid phase synthesis approach. MIP nanoparticles were obtained by immobilizing selected cardiovascular biomarkers onto glass beads that were packed in a column. Radical polymerization was performed at room temperature and the column was eluded at different temperatures. The particles that elute at elevated temperatures were retained, as their affinity for the target is the highest. The MIP particles were directly immobilized onto the surface of the thermocouples for thermal resistance measurements. Results and Conclusions The results from bacterial detection experiments (figure 1a) illustrate that the phase shift observed in the transmitted thermal wave will increase when exposing the SIP-coated aluminum chip to the target bacterium, in this case E. coli. These findings can be explained by the fact that bacteria binding to the cavities in the SIP layer will displace the urine (water-based so a good thermal conductor) that was previously present, leading to an increase of the thermal-resistance at the solid-liquid interface and a tempered propagation of the thermal wave that was send through the chip.The experiments using the nano-sized MIP particles for biomarker illustrate a similar trend and indicate that it is possible to multiplex the thermal analysis for the detection of cardiac biomarkers in serum. The data in figure 1b show that the thermal resistance of the MIP particles at the interface only change when exposed to their target (red, ST2). Exposing the MIPs to a similar cardiac biomarker (blue, H-FABP) results in a response that is similar to the response of the non-imprinted reference channel (black) with no significant change in the phase shift observed.

Molecularly Imprinted Polymer for a Smart Dispersive Micro-Solid Phase Extraction Technique for Assessing Trace Level Aflatoxins in Cultured Fish.

Molecularly imprinted technology (MIT) consists of preparing materials exhibiting specific recognition cavities to selective mimic the target analytes. The prepared materials promote selective interactions with the targets and avoid interactions of concomitants from complex food, biological, clinical, and environmental matrices. This chapter provides information on a recent development of a vortex-assisted micro-solid phase extraction using a molecularly imprinted polymer (MIP) as an adsorbent for aflatoxins (AFs) determination in cultured fish. MIP particles were synthesized by precipitation polymerization using 5,7-dimethoxycoumarin as a dummy template, methacrylic acid as a functional monomer, divinylbenzene as a cross-linker, and 2,2-azobisisobutyronitrile as an initiator. Polymerization following the precipitation method guarantees homogeneous particle size distribution and the integrity of the imprinted cavities. The MIP microparticles were found to have 5μm in diameter and a spherical shape. Important parameters such as sample extract pH, adsorption stirring speed and time, desorption stirring speed and time, elution solvent composition and volume, and polymer mass, were fully optimized. The pre-concentration method allows therefore the assessment of four major AFs (B1, B2, G1, and G2) present in cultured fish at very low levels, with pre-concentration factors from 15 to 50 depending of the volume of extract used for performing the dispersive micro-solid phase extraction (D-μ-SPE).

Synthesis of Molecularly Imprinted Polymers by Two-Step Swelling and Polymerization.

Synthesis of a molecularly imprinted polymer (MIP) by two-step swelling and polymerization is described. Monodisperse, spherical MIP particles, whose diameters are ca. 5-9μm, are prepared using a polystyrene particle as a shape template and dibutyl phthalate as an activating solvent. The obtained MIPs are suitable for separation media in liquid chromatography or solid-phase extraction media. Procedures for synthesis of MIPs and restricted access media (RAM)-MIP, packing of MIPs and RAM-MIPs, and application of MIPs and RAM-MIPs for selective separation and extraction of a target compound(s) are described.