Efficient development of a magnetic molecularly imprinted polymer for selective determination of trimethoprim and sulfamethoxazole in milk

Advances in magnetic analytical extraction techniques for detecting antibiotic residues in edible samples

The widespread use of antibiotics in agricultural and animal husbandry to treat bacterial illnesses has resulted in a rise in antibiotic-resistant bacteria. These bacteria can grow when antibiotic residues are present in food items, especially in edible animal products. As a result, it is crucial to monitor and regulate the amounts of antibiotics in food. Magnetic analytical extractions (MAEs) have emerged as a potential approach for extracting antibiotic residues from food using magnetic nanoparticles (MNPs). Recent improvements in MAEs have resulted in the emergence of novel MNPs with better selectivity and sensitivity for the extraction of antibiotic residues from food samples. Consequently, this review paper addresses current developments in MAE for extracting antibiotic residues from edible samples. It also provides a critical analysis of contemporary MAE practices. The current issues and potential future developments in this field are also discussed, thereby providing a framework for future study paths.

Advancements and greenification potential of magnetic molecularly imprinted polymers for chromatographic analysis of veterinary drug residues in milk

Milk, as a widely consumed nutrient-rich food, is crucial for bone health, growth, and overall nutrition. The persistent application of veterinary drugs for controlling diseases and heightening milk yield has imparted substantial repercussions on human health and environmental ecosystems. Due to the high demand, fresh consumption, complex composition of milk, and the potential adverse impacts of drug residues, advanced greener analytical methods are necessitated. Among them, functional materials-based analytical methods attract wide concerns. The magnetic molecularly imprinted polymers (MMIPs), as a kind of typical functional material, possess excellent greenification characteristics and potencies, and they are easily integrated into various detection technologies, which have offered green approaches toward analytes such as veterinary drugs in milk. Despite their increasing applications and great potential, MMIPs' use in dairy matrices remains underexplored, especially regarding ecological sustainability. This work reviews recent advances in MMIPs' synthesis and application as efficient sorbents for veterinary drug extraction in milk followed by chromatographic analysis. The uniqueness and effectiveness of MMIPs in real milk samples are evaluated, current limitations are addressed, and greenification opportunities are proposed. MMIPs show promise in revolutionizing green analytical procedures for veterinary drug detection, aligning with the environmental goals of modern food production systems.

Magnetic solid-phase extraction based on restricted-access molecularly imprinted polymers for ultrarapid determination of ractopamine residues from food samples by capillary electrophoresis

An ultrafast, efficient, and eco-friendly method combining magnetic solid phase extraction and capillary electrophoresis with diode array detection have been developed to determine ractopamine residues in food samples. A restricted access material based on magnetic and mesoporous molecularly imprinted polymer has been properly synthesized and characterized, demonstrating excellent selectivity and high adsorbent capacity. Short-end injection capillary electrophoresis method was optimized: 75 mM triethylamine pH 7 as BGE, -20 kV, 50 mbar by hydrodynamic injection during 8 s, and capillary temperature at 25 °C; reaching ultrafast ractopamine analysis (∼0.6 min) with good peak asymmetry, and free from interfering and/or baseline noise. After sample preparation optimization, the conditions were: 1000 µL of sample at pH 6, 20 mg of adsorbent, stirring time of 120 s, 250 µL of ultrapure water as washing solvent, 1000 µL of methanol: acetic acid (7: 3, v/v) as eluent, and the adsorbent can be reused four times. In these conditions, the analytical method showed recoveries around to 100 %, linearity ranged from 9.74 to 974.0 µg kg-1, correlation coefficient (r) ≥ 0,99 in addition to adequate precision, accuracy, and robustness. After proper validation, the method was successfully applied in the analysis ractopamine residues in bovine milk and bovine and porcine muscle.

Highly Efficient Selective Extraction of Chlorpyrifos Residues from Apples by Magnetic Microporous Molecularly Imprinted Polymer Prepared by Reversible Addition-Fragmentation Chain Transfer Surface Polymerization

Chlorpyrifos, as a moderate toxic organophosphorus pesticide, is prone to lingering in the environment and cannot be monitored easily. In this study, a magnetic, microporous, molecularly imprinted polymer was synthesized by using the reversible addition-fragmentation chain transfer polymerization method. The synthesized materials were properly characterized in terms of morphology, selectivity, and sorption capacity and used as sorbents for magnetic solid phase extraction for the selective determination of chlorpyrifos in apple samples. Results showed that the magnetic microporous molecularly imprinted materials were rough and porous spheres at an average size of 5 nm. The materials were highly selective toward chlorpyrifos with a superior sorption capacity of 167.99 mg·g^-1 and were resistant to the interference of competitive pollutants. After optimization, the recoveries of chlorpyrifos reached 96.2-106.5%, and the detection limit was 0.028 μg·kg^-1 by HPLC. Based on these analytical validation results, the developed method could be effective at determining chlorpyrifos in apples.

Multisensory Systems Based on Perfluorosulfonic Acid Membranes Modified with Functionalized CNTs for Determination of Sulfamethoxazole and Trimethoprim in Pharmaceuticals

Sulfamethoxazole and trimethoprim are synthetic bacteriostatic drugs. A potentiometric multisensory system for the analysis of sulfamethoxazole and trimethoprim combination drugs was developed. Perfluorosulfonic acid membranes containing functionalized CNTs were used as the sensor materials. The CNTs' surface was modified by carboxyl, sulfonic acid, or (3-aminopropyl)trimethoxysilanol groups. The influence of the CNT concentration and the properties of their surface, as well as preliminary ultrasonic treatment of the polymer and CNT solution before the casting of hybrid membranes, on their ion-exchange capacity, water uptake, and transport properties was revealed. Cross-sensitivity of the sensors to the analytes was achieved due to ion exchange and hydrophobic interactions with hybrid membranes. An array of cross-sensitive sensors based on the membranes containing 1.0 wt% of CNTs with sulfonic acid or (3-aminopropyl)trimethoxysilanol groups enabled us to provide the simultaneous determination of sulfamethoxazole and trimethoprim in aqueous solutions with a concentration ranging from 1.0 × 10^-5 to 1.0 × 10^-3 M (pH 4.53-8.31). The detection limits of sulfamethoxazole and trimethoprim were 3.5 × 10^-7 and 1.3 × 10^-7 М. The relative errors of sulfamethoxazole and trimethoprim determination in the combination drug as compared with the content declared by the manufacturer were 4% (at 6% RSD) and 5% (at 7% RSD).

Multisensory Systems Based on Perfluorosulfonic Acid Membranes Modified with Polyaniline and PEDOT for Multicomponent Analysis of Sulfacetamide Pharmaceuticals

The degradation of sulfacetamide with the formation of sulfanilamide leads to a deterioration in the quality of pharmaceuticals. In this work, potentiometric sensors for the simultaneous determination of sulfanilamide, sulfacetamide and inorganic ions, and for assessing the degradation of pharmaceuticals were developed. A multisensory approach was used for this purpose. The sensor cross-sensitivity to related analytes was achieved using perfluorosulfonic acid membranes with poly(3,4-ethylenedioxythiophene) or polyaniline as dopants. The composite membranes were prepared by oxidative polymerization and characterized using FTIR and UV-Vis spectroscopy, and SEM. The influence of the preparation procedure and the dopant concentration on the membrane hydrophilicity, ion-exchange capacity, water uptake, and transport properties was investigated. The characteristics of the potentiometric sensors in aqueous solutions containing sulfanilamide, sulfacetamide and alkali metals ions in a wide pH range were established. The introduction of proton-acceptor groups and π-conjugated moieties into the perfluorosulfonic acid membranes increased the sensor sensitivity to organic analytes. The relative errors of sulfacetamide and sulfanilamide determination in the UV-degraded eye drops were 1.2 to 1.4 and 1.7 to 4%, respectively, at relative standard deviation of 6 to 9%.

S. M. Montenegro MC, Rodríguez-Díaz JM. Contaminants in the cow's milk we consume? Pasteurization and other technologies in the elimination of contaminants

Cow's milk is currently the most consumed product worldwide. However, due to various direct and indirect contamination sources, different chemical and microbiological contaminants have been found in cow's milk. This review details the main contaminants found in cow's milk, referring to the sources of contamination and their impact on human health. A comparative approach highlights the poor efficacy and effects of the pasteurization process with other methods used in the treatment of cow's milk. Despite pasteurization and related techniques being the most widely applied to date, they have not demonstrated efficacy in eliminating contaminants. New technologies have appeared as alternative treatments to pasteurization. However, in addition to causing physicochemical changes in the raw material, their efficacy is not total in eliminating chemical contaminants, suggesting the need for new research to find a solution that contributes to improving food safety.

Miniaturized green sample preparation approaches for pharmaceutical analysis

The development of green sample preparation procedures is an extremely important research field in which more and more applications are constantly being proposed in different areas, including pharmaceutical analysis. This review article is aimed at providing a general overview of the development of miniaturized green analytical sample preparation procedures in the pharmaceutical analysis field, with special focus on the works published between January 2017 and July 2021. Particular attention has been paid to the application of environmentally friendly solvents and sorbents as well as nanomaterials or high extraction capacity sorbents in which the solvent volumes and reagents amounts are drastically reduced, with their subsequent advantages from the sustainability point of view.

Synthesis and characterization of genistein magnetic molecularly imprinted polymers and their application in soy sauce products

In this study, a novel method based on genistein magnetic molecularly imprinted polymers (Gen-MMIPs) was developed utilizing a surface molecular imprinting technique, in which genistein was used as the template molecule and Fe₃O₄ was used as the carrier. The synthesis of Gen-MMIPs was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which indicated that the diameter of the Gen-MMIPs was approximately 500 nm. Via analysis with a vibrating sample magnetometer (VSM), the saturation magnetization of Gen-MMIPs was determined to be 24.79 emu g⁻¹. Fourier transform infrared (FT-IR) spectroscopy showed that polymer groups were on the surface of the magnetic carrier. Adsorption experiments suggested that the genistein adsorption capability of Gen-MMIPs was 5.81 mg g⁻¹, and adsorption equilibrium was achieved within 20 min. Gen-MMIPs as dispersive solid-phase extraction (dSPE) adsorbents combined with HPLC were used to selectively separate genistein in soy sauce samples, and the recoveries ranged from 85.7 to 88.5% with relative standard deviations (RSDs) less than 5%, which proved that this method can be used for the detection of genistein residues in real samples.

Magnetic molecularly imprinted polymers for extraction of S-phenylmercapturic acid from urine samples followed by high-performance liquid chromatography

In this study, magnetic molecularly imprinted polymers (MMIPs) were prepared and used as sorbents for extraction of S-phenylmercapturic acid (S-PMA) from urine samples, followed by high-performance liquid chromatography ultraviolet-visible (HPLC-UV/Vis) analysis. The MMIPs were synthesized by the copolymerization reaction of (phenylthio) acetic acid (template molecule), methacrylic acid (functional monomers) and ethylene glycol dimethacrylate (cross-linkers). The morphology, structure property and surface groups of the prepared MMIPs were characterized by scan electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray diffraction pattern, thermogravimetric analyses, Brunauer-Emmett-Teller and vibrating sample magnetometer. The selectivity of the MMIPs was investigated in the presence of interferents. Various parameters affecting the S-PMA extraction efficiency were investigated, including MMIPs amount, pH, sample volume, desorption solvent, as well as extraction and desorption time. The obtained optimal parameters were as follows: MMIPs amount (20 mg), pH (3.0), sample volume (5 mL), desorption solvent (methanol/acetic acid [9/1, v/v]), extraction time (30 minutes) and desorption time (2 minutes). The method was validated according to the Food and Drug Administration Guidance for Industry on Bioanalytical Method Validation. The calibration curve for the analyte was linear in the concentration range of 0.030-1.0 mg/L (r = 0.9995). The LOD and LOQ of the method were 0.0080 and 0.0267 mg/L, respectively. The enrichment factor of the MMIPs was 5. The relative standard deviations of intra- and inter-day tests were in the range of 3.8-5.1% and 3.9-6.3%, respectively. The recoveries at three different concentrations of 0.10, 0.50 and 0.80 mg/L ranged between 95.2% and 98.6%. In addition, the MMIPs could be reused for at least eight times. The proposed method was successfully applied to the determination of S-PMA in urine samples. In addition, this developed method could be used as a tool in the early screening and clinical diagnosis of benzene intoxication.

Efficient and selective extraction of azamethiphos and chlorpyrifos residues from mineral water and grape samples using magnetic mesoporous molecularly imprinted polymer

A magnetic mesoporous molecularly imprinted polymers was synthesized on the surface of magnetic nanoparticles silanized with 3-(trimethoxysilyl) propyl methacrylate to introduce reactive methacrylate groups. Subsequently, methacrylic acid monomers were grafted onto the surface of this adsorbent functionalized via polymerization by precipitation. Magnetic mesoporous molecularly imprinted polymer was properly characterized by different techniques and applied as adsorbent in magnetic solid phase extraction for selective determination of two organophosphorus pesticides, azamethiphos and chlorpyrifos, in mineral water and grape samples. After sample preparation optimization, recoveries of 99.56% and 98.86% were obtained for azamethiphos and chlorpyrifos, respectively. The magnetic solid phase extraction coupled to HPLC-UV presented limit of quantification of 5 ng mL^-1, linearity ranged of 5 to 1000 ng mL^-1, in addition to adequate accuracy, precision and robustness. The pesticides showed stability in the matrix and were satisfactorily quantified in real mineral water and grape samples.

Fluorescence assay of oxytetracycline in seawater after selective capture using magnetic molecularly imprinted nanoparticles

A comprehensive strategy for manufacturing a novel sorbent based on magnetic molecularly imprinted polymers (MMIPs) is addressed for selective capture of oxytetracycline from seawater. The novel MMIPs were synthesized by nano-Fe₃O₄ as sacrificial matrix and adsorption properties of the polymers demonstrate rapid adsorption kinetics, high adsorption capacity, and specificity towards oxytetracycline provided by the core-shell composite structure. After screening the critical parameters by multivariate optimization, a magnetic imprinting solid phase extraction method combined with fluorescence spectrophotometry (MMIP-SPE-FL) was constructed for sensitive determination of oxytetracycline in seawater samples. The results show a good linear response dependence on the spiking concentration of 3-100 μg L^-1, and a satisfactory limit of detection of 0.7 μg L^-1 after the MMIP-SPE preconcentration. Seven seawater samples from Jiaozhou bay were analyzed to give recoveries in the range of 89.75-107.65% with relative standard deviation values of less than 5.44% (n = 3).

Greenness of magnetic nanomaterials in miniaturized extraction techniques: A review

Green analytical chemistry principles should be followed, as much as possible, and particularly during the development of analytical sample preparation methods. In the past few years, outstanding materials such as ionic liquids, metal-organic frameworks, carbonaceous materials, molecularly imprinted materials, and many others, have been introduced in a wide variety of miniaturized techniques in order to reduce the amount of solvents and sorbents required during the analytical sample preparation step while pursuing more efficient extraction methods. Among them, magnetic nanomaterials (MNMs) have gained special attention due to their versatile properties. Mainly, their ability to be separated from the sample matrix using an external magnetic field (thus enormously simplifying the entire process) and their easy combination with other materials, which implies the inclusion of a countless number of different functionalities, highly specific in some cases. Therefore, MNMs can be used as sorbents or as magnetic support for other materials which do not have magnetic properties, the latter permiting their combination with novel materials. The greenness of these magnetic sorbents in miniaturized extractions techniques is generally demonstrated in terms of their ease of separation and amount of sorbent required, while the nature of the material itself is left unnoticed. However, the synthesis of MNMs is not always as green as their applications, and the resulting MNMs are not always as safe as desired. Is the analytical sample preparation field ready for using green magnetic nanomaterials? This review offers an overview, from a green analytical chemistry perspective, of the current state of the use of MNMs as sorbents in microextraction strategies, their preparation, and the analytical performance offered, together with a critical discussion on where efforts should go.

Antimicrobial magnetic poly(GMA) microparticles: synthesis, characterization and lysozyme immobilization

Micron-sized magnetic particles currently find a wide range of applications in many areas including biotechnology, biochemistry, colloid sciences and medicine. In this study, magnetic poly(glycidyl methacrylate) microparticles were synthesized by providing a polymerization around Fe(II)-Ni(II) magnetic double salt. Adsorption of lysozyme protein from aqueous systems was studied with these particles. Adsorption studies were performed with changing pH values, variable amount of adsorbent, different interaction times and lysozyme amounts. The adsorption capacity of the particles was investigated, and a value of about 95.6 mg lysozyme/g microparticle was obtained. The enzyme activity of the immobilized lysozyme was examined and found to be more stable and reusable compared to the free enzyme. The immobilized enzyme still showed 80% activity after five runs and managed to maintain 78% of its initial activity at the end of 60 days. Besides, in the antimicrobial analysis study for six different microorganisms, the minimum inhibitory concentration value of lysozyme immobilized particles was calculated as 125 μg/mL like free lysozyme. Finally, the adsorption interaction was found to be compatible with the Langmuir isotherm model. Accordingly, it can be said that magnetic poly(GMA) microparticles are suitable materials for lysozyme immobilization and immobilized lysozyme can be used in biotechnological studies.

Mesoporous molecularly imprinted polymer core@shell hybrid silica nanoparticles as adsorbent in microextraction by packed sorbent for multiresidue determination of pesticides in apple juice

In this work, we report the synthesis of a mesoporous molecularly imprinted polymer on the surface of silica nanoparticles (core@mMIP) to be applied as adsorbent in microextraction by packed sorbent (MEPS) for selective determination of pesticides in apple juice. The core@mMIP was properly characterized, showing good adhesion of the polymer to the silica core. The best extraction conditions were: 200 µL of ultrapure water as washing solvent, 150 µL of acetonitrile as eluent, 100 µL of sample at pH 2.5, five draw-eject cycles and 8 mg of adsorbent. Thereby, recoveries of 96.12 ± 1.05%, 76.88 ± 6.18% and 76.18 ± 5.57% were obtained for pyriproxyfen (PPX), deltamethrin (DTM) and etofenprox (ETF), respectively. After validation, the method presented linearity in the range of 0.02-10 µg mL^-1 (r > 0.99), limit of detection of 0.005 µg mL^-1, satisfactory selectivity, and proper precision and accuracy. The method was successfully applied real samples of processed and fresh apple juice.

Synthesis of Magnetic Molecularly Imprinted Polymer Sorbents for Isolation of Parabens from Breast Milk

Magnetic molecularly imprinted polymers (MMIPs) are an invaluable asset in the development of many methods in analytical chemistry, particularly sample preparation. Novel adsorbents based on MMIPs are characterized by high selectivity towards a specific analyte due to the presence of a specific cavity on their polymer surface, enabling the lock-key model interactions to occur. In addition, the magnetic core provides superparamagnetic properties that allow rapid separation of the sorbent from the sample solution. Such a combination of imprinted polymers with a magnetic core has an innovative influence on the development of separation techniques. Hence, the present study describes the synthesis of MMIPs with 17β-estradiol used as a template molecule in the production of imprinted polymers. The as-prepared sorbent was used for a sorption/desorption study of five parabens from breast milk samples. The obtained results were characterized by sorption efficiency exceeding 92%, which shows the high affinity of the analytes to the functional groups on the sorbent. The final determination of the selected analytes was done with high-performance liquid chromatography using a fluorometric detector. The determined linearity ranges for selected parabens were characterized by high determination coefficients (r² from 0.9992 to 0.9999), and the calculated limit of detection (LOD) and limit of quantification (LOQ) for the identified compounds were low (LOD from 1.1-2.7 ng mL^-1; LOQ from 3.6-8.1 ng mL^-1), which makes their quantitative analysis in real samples feasible.

Selective separation and purification of polydatin by molecularly imprinted polymers from the extract of Polygoni Cuspidati Rhizoma et Radix, rats' plasma and urine

Molecularly imprinted polymers (MIPs) based on polydatin were prepared by precipitation polymerization method. Synthesis process of MIPs was optimized by discussion of functional monomers, porogens and the molar ratio of template- functional monomer-cross linker. Then, MIPs were prepared with polydatin as the template, 4-vinyl pyridine as the functional monomer, ethylene glycol dimethyl acrylate as the cross linker, acetonitrile as the porogen and the molar ratio of template-monomer-cross linker at 1:10:20. Scanning electron microscopy and Fourier transform infrared spectrometer were used to inspect macroscale and chemical bond of MIPs. Adsorption capability and selectivity of MIPs to polydatin were investigated by carrying out the static, dynamic and selective experiments. The results showed MIPs performed high adsorption ability and selectivity to polydatin, indicating MIPs could be used to separate and enrich polydatin from the complex systems. Finally, MIPs were applied as the adsorbent for isolation and purification of polydatin from the extract of Polygoni Cuspidati Rhizoma et Radix, rats' plasma and urine samples. MIPs were successfully used to separate polydatin from the Polygoni Cuspidati Rhizoma et Radix and recovery ranged from 89.2% to 91.6%. The maximum concentration of polydatin in rats' plasma and urine samples was 2.84 ± 0.0748 µg mL^-1 and 2.64 ± 0.485 µg mL^-1, respectively. Moreover, to compare with the MIPs method, organic solvent methods were used to analyze the polydatin in rats' plasma and urine samples. The results illustrated MIPs method was effective and selective for enrichment of polydatin from the medicinal plants and biological samples.