Determination of sulfonamides in bovine milk with column-switching high performance liquid chromatography using surface imprinted silica with hydrophilic external layer as restricted access and selective extraction material

Molecularly imprinted polymer-coated silica microbeads for high-performance liquid chromatography

Molecularly imprinted polymer (MIP)-based chromatographic separation materials, owing to their advantages of unique selectivity, low cost, suitable reproducibility, and acceptable stability, have attracted a great deal of research in different fields. In this investigation, a new type of MIP-coated silica (MIP/SiO2) separation material was developed using sulfamethoxazole as a template; the specific recognition ability of MIP and appropriate physicochemical properties (abundant Si-OH, suitable pore structure, good stability, etc.) of SiO2 microbeads were combined. The MIP/SiO2 separation materials were characterized carefully. Then, various compounds (such as sulfonamides, ginsenosides, nucleosides, and several pesticides) were used to comprehensively evaluate the chromatographic performances of the MIP/SiO2 column. Furthermore, the chromatographic performances of the MIP/SiO2 column were compared with those of other separation materials (such as non-imprinted polymer-coated silica, C18/SiO2, and bare silica) packed columns. The resolution value of all measured compounds was more than 1.51. The column efficiencies of 13 510 plates per meter (N m-1) for sulfamethoxazole, 11 600 N m-1 for ginsenoside Rd, and 10 510 N m-1 for 2'-deoxyadenosine were obtained. The acceptable results verified that the MIP/SiO2 column can be applied to separate highly polar drugs such as sulfonamides, ginsenosides, nucleosides, and pesticides.

Molecularly imprinted polymers in online extraction liquid chromatography methods: Current advances and recent applications

BACKGROUND

One of the primary objectives in green analytical practices is the seamless integration of extraction and separation steps, resulting in the augmentation of both analytical throughput and method performance. Consequently, the exploration of prospective sorbent materials has drawn significant attention in the scientific community, particularly concerning the potential for online procedures. Employing the optimal sorbent material within an automated analytical approach holds the promise of elevating the precision of the analytical evaluation. Molecularly imprinted polymers (MIPs) excel in specific analyte interaction within complex matrices. However, MIPs' full potential was not widely exploring especially for online analytical methodologies.

RESULTS

Here is presented a comprehensive overview of the current applications of MIPs as sorbent materials within integrated and automated separation methodologies applied to diverse matrices including biological, food, and environmental samples. Notably, their primary advantage, as evidenced in the literature, lies in their exceptional selectivity for the target analyte discussed according to the adopted synthesis protocol. Furthermore, the literature discussed here illustrates the versatility of MIPs in terms of modification with one or more phases which are so-called hybrid materials, such as molecularly imprinted monoliths (MIM), the molecularly imprinted ionic liquid polymer (IL-MIP), and restricted access to molecularly imprinted polymer (RAMIP). The reported advantages enhance their applicability in integrated and automated separation procedures, especially to the column switching methods, across a broader spectrum of applications.

SIGNIFICANCE

This revision aims to demonstrate the MIP's potential as a sorbent phase in integrated and automated methods, this comprehensive overview of MIP polymers in integrated and automated separation methodologies can be used as a valuable guide, inspiring new research on developing novel horizons for MIP applications to have their potential emphasized in analytical science and enhanced to the great analytical methods achievement.

Highly selective enrichment and direct determination of imazethapyr residues from milk using magnetic solid-phase extraction based on restricted-access molecularly imprinted polymers

Restricted access media magnetic molecularly imprinted polymers (RAM-MMIPs) were prepared as magnetic solid phase extraction (M-SPE) material by reversible addition fragmentation chain transfer (RAFT) technique. The resulting RAM-MMIPs had a uniform, imprinted, hydrophilic layer (63 nm), good binding capacity (34.85 mg g-1) and satisfactory selectivity. In addition, these RAM-MMIPs had a robust ability to eliminate the interference of protein macromolecules. These RAM-MMIPs were then coupled with HPLC/UV to identify imazethapyr (IM) residues in untreated milk samples. Several major factors would affect M-SPE extraction efficiency, such as the amount of RAM-MMIPs, pH, extraction time of the sample solution, and the volume ratio of the elution solvent. Under the optimal conditions, the developed method had good linearity (R2 > 0.9993), low detection limit (2.13 μg L-1), and low quantitative limit (7.15 μg L-1). These results indicated this proposed approach is an efficient method for direct enrichment and detection of IM herbicides in milk and other biological samples.

Restricted access magnetic imprinted microspheres for directly selective extraction of tetracycline veterinary drugs from complex samples

A novel restricted access media-magnetic molecularly imprinted polymers (RAM-MMIPs) was prepared as magnetic-solid phase extraction (M-SPE) material for tetracyclines (TCs). The RAM-MMIPs can not only specifically adsorb target molecules in samples, but also effectively eliminate the interference of protein macromolecules. The protein exclusion rate is 99.4%. Besides, RAM-MMIPs have a uniform imprinted and hydrophilic layer (600 nm), rapid binding kinetic (35 min), high selectivity and larger adsorption capacity. The M-SPE was coupled with HPLC/UV to extract TCs from untreated milk and egg samples, and several major factors affecting M-SPE efficiency were optimized. Under optimized conditions, the developed method achieved good linearity (R²>0.9989), lower limits of detection (LOD) and higher recoveries of TCs. For milk samples, the LOD is 1.03-1.31 μg L^-1 and the recovery is 86.7% to 98.6% with relative standard deviation (RSD) of 1.4-5.7%. For the egg samples, the LOD, recovery and RSD are 2.21-2.67 μg L^-1, 84.2-96.5% and 1.7-5.9%, respectively. Consequently, this work provides an improved strategy for the selective extraction and detection of target molecules directly from complex samples with proteins.

Butyl Methacrylate-Co-Ethylene Glycol Dimethacrylate Monolith for Online in-Tube SPME-UHPLC-MS/MS to Determine Chlopromazine, Clozapine, Quetiapine, Olanzapine, and Their Metabolites in Plasma Samples

This manuscript describes a sensitive, selective, and online in-tube solid-phase microextraction coupled with an ultrahigh performance liquid chromatography-tandem mass spectrometry (in-tube SPME-UHPLC-MS/MS) method to determine chlopromazine, clozapine, quetiapine, olanzapine, and their metabolites in plasma samples from schizophrenic patients. Organic poly(butyl methacrylate-co-ethylene glycol dimethacrylate) monolith was synthesized on the internal surface of a fused silica capillary (covalent bonds) for in-tube SPME. Analyte extraction and analysis was conducted by connecting the monolithic capillary to an UHPLC-MS/MS system. The monolith was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The developed method presented adequate linearity for all the target antipsychotics: R² was higher than 0.9975, lack-of-fit ranged from 0.115 to 0.955, precision had variation coefficients lower than 14.2%, and accuracy had relative standard error values ranging from -13.5% to 14.6%, with the exception of the lower limit of quantification (LLOQ). The LLOQ values in plasma samples were 10 ng mL^-1 for all analytes. The developed method was successfully applied to determine antipsychotics and their metabolites in plasma samples from schizophrenic patients.

A restricted access molecularly imprinted polymer coating on metal–organic frameworks for solid-phase extraction of ofloxacin and enrofloxacin from bovine serum

A restricted access molecularly imprinted polymer (RAMIP) crosslinked with bovine serum albumin (BSA) was prepared on the surface of the mesoporous UiO-66-NH₂ metal–organic framework (MOF). The surface morphology, imprinting behavior, and protein exclusion properties of UiO-66-NH₂@RAMIP@BSA were investigated. The maximum adsorption capacity was 50.55 mg g⁻¹ for ofloxacin, with a 99.4% protein exclusion rate. Adsorption equilibrium was reached in 9 min. Combined with RP-HPLC, a solid-phase extraction column filled with UiO-66-NH₂@RAMIP@BSA was used to selectively enrich and analyze ofloxacin and enrofloxacin antibiotics from bovine serum with recoveries of 93.7–104.2% with relative standard deviations of 2.0–4.5% (n = 3). The linear range and the limit of detection were 0.1–100 μg mL⁻¹ and 15.6 ng mL⁻¹, respectively. These results suggest that UiO-66-NH₂@RAMIP@BSA is an efficient pretreatment adsorbent for biological sample analysis.

A restricted access molecularly imprinted polymer (RAMIP) crosslinked with bovine serum albumin (BSA) was prepared on the surface of the mesoporous UiO-66-NH₂ metal–organic framework (MOF).

Trends in Microextraction-Based Methods for the Determination of Sulfonamides in Milk

Sulfonamides (SAs) represent a significant category of pharmaceutical compounds due to their effective antimicrobial characteristics. SAs were the first antibiotics to be used in clinical medicine to treat a majority of diseases, since the 1900s. In the dairy farming industry, sulfa drugs are administered to prevent infection, in several countries. This increases the possibility that residual drugs could pass through milk consumption even at low levels. These traces of SAs will be detected and quantified in milk. Therefore, microextraction techniques must be developed to quantify antibiotic residues, taking into consideration the terms of Green Analytical Chemistry as well.

Column switching UHPLC–MS/MS with restricted access material for the determination of CNS drugs in plasma samples

Background: Polypharmacy is a common practice in schizophrenia. Consequently, therapeutic drug monitoring is usually adopted to maintain the concentrations of the drugs in the plasma within a targeted therapeutic range, to maximize therapeutic efficiency and to diminish adverse side effects. Methodology: This study reports on a column switching UHPLC–MS/MS method to determine psychotropic drugs in plasma samples simultaneously. Results: The method was linear from 0.025 to 1.25 ng ml-1 with R2 above 0.9950 and the lack of fit test (p > 0.05). The precision values presented coefficients of variation lower than 12%, and the relative standard error of the accuracy were lower than 14%. Conclusion: The column switching UHPLC–MS/MS method developed herein successfully determined drugs in schizophrenic patients’ plasma samples for therapeutic drug monitoring.

Preparation of a monolithic cation-exchange material with hydrophilic external layers by two-step reversible addition-fragmentation chain transfer polymerization

In recent years, the efficient analysis of biological samples has become more important due to the advances of life science and pharmaceutical research and practice. Because biological sample pretreatment is the bottleneck for fast process, material development for efficient sample process in the high-performance liquid chromatography analysis is highly desirable. In this research, a cation-exchange restricted access monolithic column was synthesized by a reversible addition-fragmentation chain transfer polymerization method. Utilizing the controlled/living property of the reversible addition-fragmentation chain transfer method, a monolithic column of cross-linked poly(sulfopropyl methacrylate) was prepared first and then linear poly(glycerol mono-methacrylate) was immobilized covalently on the surface of the polymer. The monolithic material has both functionalities of cation-exchange and protein exclusion. Protein recovery of 94.6% was obtained after grafting of poly(glycerol mono-methacrylate) while the cation-exchange property of the column is still retained. In the study, the relation between the synthetic conditions and properties of the materials was studied. The synthesis conditions including the porogen, monomer concentration, and ratio of monomers/initiator/reversible addition-fragmentation chain transfer agent were optimized. The study provided a method for the preparation of restricted access monolithic columns: a bifunctional material by reversible addition-fragmentation chain transfer polymerization method.

Silica nanoparticle based techniques for extraction, detection, and degradation of pesticides

Silica nanoparticles (SiNPs) find applications in the fields of drug delivery, catalysis, immobilization and sensing. Their synthesis can be mediated in a facile manner and they display broad range compatibility and stability. Their existence in the form of spheres, wires and sheets renders them suitable for varied purposes. This review summarizes the use of silica nanostructures in developing techniques for extraction, detection and degradation of pesticides. Silica nanostructures on account of their sorbent properties, porous nature and increased surface area allow effective extraction of pesticides. They can be modified (with ionic liquids, silanes or amines), coated with molecularly imprinted polymers or magnetized to improve the extraction of pesticides. Moreover, they can be altered to increase their sensitivity and stability. In addition to the analysis of pesticides by sophisticated techniques such as High Performance Liquid Chromatography or Gas chromatography, silica nanoparticles related simple detection methods are also proving to be effective. Electrochemical and optical detection based on enzymes (acetylcholinesterase and organophosphate hydrolase) or antibodies have been developed. Pesticide sensors dependent on fluorescence, chemiluminescence or Surface Enhanced Raman Spectroscopic responses are also SiNP based. Moreover, degradative enzymes (organophosphate hydrolases, carboxyesterases and laccases) and bacterial cells that produce recombinant enzymes have been immobilized on SiNPs for mediating pesticide degradation. After immobilization, these systems show increased stability and improved degradation. SiNP are significant in developing systems for effective extraction, detection and degradation of pesticides. SiNPs on account of their chemically inert nature and amenability to surface modifications makes them popular tools for fabricating devices for 'on-site' applications.

Analysis of tricyclic antidepressants in human plasma using online-restricted access molecularly imprinted solid phase extraction followed by direct mass spectrometry identification/quantification

The use of a new class of hybrid materials, called restricted access molecularly imprinted polymers (RAMIPs) seems to present a good strategy for the sample preparation of complex matrices, since these materials combine good protein elimination capacity with high degree selectivity. Mass spectrometers (MS) have been successfully used for polar drug identification and quantification. In order to combine the advantages of both RAMIPs and mass spectrometry, we proposed a study that joins these properties in a single system, where we could analyse tricyclic antidepressants from human plasma, without offline extraction or chromatographic separation. A RAMIP for amitriptyline was synthesised by the bulk method, using methacrylic acid as a functional monomer and glycidilmethacrylate as a hydrophilic co-monomer. Then, epoxide ring openings were made and the polymer was covered with bovine serum albumin (BSA). A column filled with RAMIP-BSA was coupled to a MS/MS instrument in an online configuration, using water as loading and reconditioning mobile phase and a 0.01% acetic acid aqueous solution: acetonitrile at 30:70 as elution mobile phase. The system was used for on-line extraction and simultaneous quantification of nortriptyline, desipramine, amitriptyline, imipramine, clomipramine and clomipramine-d3 (IS) (from 15.0 to 500.0μgL^-1) from plasma samples. The correlation coefficient was higher than 0.99 for all analytes. The CV (coefficient of variation) values ranged from 1.34% to 19.13% for intra assay precision and 1.32-19.77% for inter assay precision. The E% (relative error) values ranged from -19.15% to 19.51% for intra assay accuracy and from -9.04% to 16.22% for inter assay accuracy.

An overview of multidimensional liquid phase separations in food analysis

Food safety is a priority public health concern that demands analytical methods capable to detect low concentration level of contaminants (e.g. pesticides and antibiotics) in different food matrices. Due to the high complexity of these matrices, a sample preparation step is in most cases mandatory to achieve satisfactory results being usually tedious, lengthy, and prone to the introduction of errors. For this reason, many research groups have focused efforts on the development of online systems capable to do the cleanup, concentration, and separation steps at once through multidimensional separation techniques (MDS). Among several possible setups, the most popular are the multidimensional chromatographic techniques (MDC) that consist in combining more than one mobile and/or stationary phase to provide a satisfactory separation. In the present review, we selected a variety of multidimensional separation systems used for food contaminant analysis in order to discuss the instrumentation aspects, the concept of orthogonality, column approaches used in these systems, and new materials that can be used in these columns. Selected classes of contaminants present in food matrices are introduced and discussed as example of the potential applications of multidimensional liquid phase separation techniques in food safety.

Layer-by-layer fabrication of restricted access media-molecularly imprinted magnetic microspheres for magnetic dispersion microextraction of bisphenol A from milk samples

A novel hydrophilic BPA-imprinted magnetic microsphere was prepared with specific molecular recognition (2.54), water compatibility and exclusion biomacromolecules.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Recent advances in sample preparation techniques and methods of sulfonamides detection - A review

Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid-liquid and solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed.

Ionic liquid-based aqueous two-phase system extraction of sulfonamides in milk

A simple method for the determination of six sulfonamides (SAs) in milk samples was developed. 1-Butyl-3-methylimidazolium tetrafluoroborate and trisodium citrate dihydrate were used to form aqueous two-phase system. The aqueous two phase system was applied to the extraction of the SAs and the determination of the analytes was performed by high-performance liquid chromatography. To achieve optimum extraction performance, several experimental parameters, including the type and the amount of salt, the type and amount of ionic liquid, ultrasonic time and pH of sample solution, were investigated and optimized. Under the optimal experimental conditions, good linearity was observed in the range of 8.55-1036.36ngmL(-1). The limits of detection and quantification were in the range of 2.04-2.84 and 6.73-9.37ngmL(-1), respectively. The present method was successfully applied to the determination of SAs in milk samples, and the recoveries of analytes were in the range of 72.32-108.96% with relative standard deviations ranging from 0.56 to 12.20%. The results showed that the present method was rapid, feasible and environmentally friendly.