Monolithic Capillary Research Articles

In Vivo Biotransformation of the Fusion Protein Tetranectin-Apolipoprotein A1 Analyzed by Ligand-Binding Mass Spectrometry Combined with Quantitation by ELISA.

The in vivo biotransformation of a novel fusion protein tetranectin/apolipoprotein A1 (TN-ApoA1) was investigated by ligand-binding mass spectrometry (LB-MS) in support of enzyme-linked immunosorbent assays (ELISA). The main focus was on catabolites formed by proteolysis of the fusion protein in rabbit following intravenous administration of lipidated TN-ApoA1. The drug and its catabolites were isolated from rabbit plasma by immunocapture with a monoclonal antibody (mAb) binding to the fusion region of TN-ApoA1. The captured drug and catabolites were released from the streptavidin-coated magnetic beads, separated by monolithic RP capillary HPLC, and online detected by high-resolution mass spectrometry. In addition, the same extract was digested with LysN to confirm or further narrow down the structure of the found catabolites. Two pharmacologically active catabolites were identified with conserved fusion region. The major catabolite [3-285] was formed by truncation of AP at the N-terminus and the minor catabolite [29-270] by truncations of either side of the TN-ApoA1 sequence. Since the ELISA determined the sum of TN-ApoA1, along with its two main catabolites, the individual PK profiles of all three components could be derived by applying their mass peak composition for each sampling point. Parent drug accounted for 25% of drug-related material, whereas that of the catabolites [3-285] and [29-270] accounted for 66% and 9%, respectively. This result could be obtained without catabolite specific ELISAs or quantitative LC-MS assays. It was also confirmed that all relevant functional molecules of TN-ApoA1 in the plasma samples were quantified by the ELISA, which provided a good relationship for pharmacokinetic/pharmacodynamic evaluations.

Coupling of metal-organic frameworks-containing monolithic capillary-based selective enrichment with matrix-assisted laser desorption ionization-time-of-flight mass spectrometry for efficient analysis of protein phosphorylation

Protein phosphorylation is a major post-translational modification, which plays a vital role in cellular signaling of numerous biological processes. Mass spectrometry (MS) has been an essential tool for the analysis of protein phosphorylation, for which it is a key step to selectively enrich phosphopeptides from complex biological samples. In this study, metal-organic frameworks (MOFs)-based monolithic capillary has been successfully prepared as an effective sorbent for the selective enrichment of phosphopeptides and has been off-line coupled with matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) for efficient analysis of phosphopeptides. Using š-casein as a representative phosphoprotein, efficient phosphorylation analysis by this off-line platform was verified. Phosphorylation analysis of a nonfat milk sample was also demonstrated. Through introducing large surface areas and highly ordered pores of MOFs into monolithic column, the MOFs-based monolithic capillary exhibited several significant advantages, such as excellent selectivity toward phosphopeptides, superb tolerance to interference and simple operation procedure. Because of these highly desirable properties, the MOFs-based monolithic capillary could be a useful tool for protein phosphorylation analysis.

One-Pot Approach to Prepare Organo-silica Hybrid Capillary Monolithic Column with Intact Mesoporous Silica Nanoparticle as Building Block.

A facile “one-pot” approach to prepare organo-silica hybrid capillary monolithic column with intact mesoporous silica nanoparticle (IMSN) as crosslinker and building block was described. An IMSN crosslinked octadecyl-silica hybrid capillary monolithic column (IMSN-C18 monolithic column) was successfully prepared, and the effects of fabrication conditions (e.g. concentration of intact mesoporous silica nanoparticle, polycondensation temperature, content of vinyltrimethoxysilane and stearyl methacrylate) on the structures of the IMSN-C18 monolithic column were studied in detail. The IMSN-C18 hybrid monolithic column possessed uniform morphology, good mechanical and pH stability (pH 1.1–11), which was applied to the separations of alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), as well as proteins. The minimum plate height of 10.5 μm (corresponding to 95000 N m−1) for butylbenzene and high reproducibility were achieved. The analysis of tryptic digest of bovine serum albumin (BSA) was carried out on the IMSN-C18 monolithic column by cLC coupled mass spectrometry (cLC-MS/MS), with the protein sequence coverage of 87.5% for BSA, demonstrating its potential application in proteomics.

Separation and identification of antidepressants by acrylate-based monolithic column capillary electrochromatography with UV detection.

This paper details a method for separation and identification of six antidepressant compounds using an acrylate-based porous monolithic capillary. Detection takes place using CEC coupled with UV or mass spectrometric detection. The CEC-UV method provides an effective and efficient method for the separation and identification of the analytes. Spiked urine samples were utilized to check method capability, and a liquid-liquid extraction procedure was developed to perform sample extraction. Detection limits ranged from 10 to 30 ng/mL.

Preparation and evaluation of micro and meso porous silica monoliths with embedded carbon nanoparticles for the extraction of non-polar compounds from waters

A novel hybrid micro and meso porous silica monolith with embedded carbon nanoparticles (Si-CNPs monolith) was prepared inside a fused silica capillary (3cm in length) and used as a sorbent for solid-phase microextraction. The hybrid monolithic capillary was synthetized by hydrolysis and polycondensation of a mixture of tetraethoxysilane (TEOS), ethanol, and three different carbon nanoparticles such as carboxylated single-walled carbon nanotubes (c-SWCNTs), carboxylated multi-walled carbon nanotubes (c-MWCNTs), and oxidized single-walled carbon nanohorns (o-SWNHs) via a two-step catalytic sol-gel process. Compared with silica monolith without carbon nanoparticles, the developed monolithic capillary column exhibited a higher extraction efficiency towards the analytes which can be ascribed to the presence of the carbon nanoparticles. In this regard, the best performance was achieved for silica monolith with embedded c-MWCNTs. The resulted monolithic capillaries were also characterized by scanning electron microscopy (SEM), elemental analysis and nitrogen intrusion porosimetry. Variables affecting to the preparation of the sorbent phase including three different carbon nanoparticles and extraction parameters were studied in depth using polycyclic aromatic hydrocarbons (PAHs) as target analytes. Gas chromatography-mass spectrometry was selected as instrumental technique. Detection limits range from 0.1 to 0.3μgL−1, and the inter-extraction units precision (expressed as relative standard deviation) is between 5.9 and 14.4%.

Preparation of a thermoresponsive polymer grafted polystyrene monolithic capillary for the separation of bioactive compounds

To develop aqueous microseparation columns for bioactive compounds, a thermoresponsive polymer grafted polymer monolith was prepared inside silica capillaries having an I.D. of 100μm by polymerization of styrene (St) with m/p-divinylbenzene (DVB) in the presence of polydimethylsiloxane as porogen, followed by surface-initiated atom transfer radical polymerization (SI-ATRP) of N-isopropylacrylamide (NIPAAm). SEM analysis indicated that the resulting poly(N-isopropylacrylamide) (PNIPAAm) grafted polystyrene monolith had a consecutive three-dimensionally interconnected structure and through-pores, similar to the base polystyrene (PSt) monolith. The elution behavior of steroids with different hydrophobicity was evaluated using micro-high-performance liquid chromatography in sole aqueous mobile phase. Temperature dependent interaction changes were observed between steroids and the PNIPAAm modified surfaces. Furthermore, the interaction between bioactive compounds and the PNIPAAm grafted PSt surfaces was controlled and eventually separate these molecules with different hydrophobicities by simple temperature modulation in aqueous environment. The PNIPAAm grafted PSt monolithic capillary showed improved separation properties of bioactive compounds, compared with a PNIPAAm grafted hollow capillary in aqueous environment.

Enantiomer Separation of Acidic Chiral Compounds on a tert‐Butylcarbamoylquinine‐Silica Hybrid Monolith by Capillary Electrochromatography

A tert‐butylcarbamoylquinine ( tBuCQUI)‐incorporated silica hybrid monolithic (QUI–SHM) capillary was prepared by “one‐pot” approach via simultaneous sol–gel reaction of tetramethoxysilane and vinyltrimethoxysilane and free radical polymerization of tBuCQUI. A set of acidic chiral drugs were enantioseparated on QUI–SHM in mobile phases consisting of acetonitrile (ACN), methanol (MeOH), acetic acid (AcOH), and triethylamine (TEA). Influences of ACN/MeOH ratio, AcOH/TEA ratio, and their concentrations on enantioseparation were investigated. Baseline separations of enantiomers of all the compounds investigated were achieved with a mobile phase of 60:38 (v/v) ACN/MeOH containing 350 mM AcOH and 30 mM TEA under the applied voltage of −10 kV at 25°C.

Preparation of graphene oxide-modified affinity capillary monoliths based on three types of amino donor for chiral separation and proteolysis

Novel graphene oxide (GO)-modified affinity capillary monoliths were developed employing human serum albumin (HSA) or pepsin as chiral selector. Three types of amino donors for GO immobilization, including ammonium hydroxide (NH4OH), ethanediamine (EDA) and polyethyleneimine (PEI), were applied to explore the effect of spacer arm on enantioseparation. It was observed that HSA-GO-EDA-based affinity capillary monoliths exhibited better chiral recognition ability in comparison with the other two spacer-based monoliths. Under the optimized conditions, the obtained columns revealed satisfactory repeatability concerning column-to-column, run-to-run and interday repeatability. In addition, the impact of GO concentration on enantiomeric separation was also investigated. HSA-GO-EDA-based affinity capillary monoliths provided higher chiral selectivity for nine pairs of enantiomers compared to the columns without GO. Furthermore, the influence of amino donors and GO on proteolytic activity of pepsin-based immobilized enzymatic reactor (IMER) was discussed. Unfortunately, pepsin-GO-PEI-based affinity capillary monoliths possessed the highest protein digestion capacity, which was different from the effect of amino donors on enantiorecognition. Moreover, GO presented as a favorable choice to improve the enzymatic activity of IMER. These results proved that GO-functionalized affinity capillary monoliths have promising potential for chiral separation and proteolysis.

High-Throughput and Low-Cost Analysis of Trace Volatile Phthalates in Seafood by Online Coupling of Monolithic Capillary Adsorbent with GC-MS.

A simple, sensitive, and high-throughput method was developed for the determination of six volatile phthalate esters-dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzylbutyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP)-in seafood samples by using monolith adsorbent in a capillary coupled to a gas chromatography-mass spectrometry (GC-MS) system. The freeze-dried samples were subjected to an ultrasonication with hexane, followed by vortex mixing. The liquid extract was quantitatively determined by a direct application to an online silica monolith capillary adsorbent coupled with a gas chromatograph with mass spectrometric detection. Method validation in seafood matrix gave recoveries of 72.8-85.4% and a detection limit of 6.8-10.0 ng g(-1) for bivalve samples. Reusability of the monolith capillary for trapping coextracted matrix was up to six times, allowing high-throughput analysis at the parts per billion level. When compared with the Food and Environment Research Agency (FERA) method, no significant difference in the result was observed, confirming the method was valid and applicable for the routine analysis of phthalates in seafood samples for food and environmental laboratories.

A comparative proteomics study of a synovial cell line stimulated with TNF-α.

To elucidate the pathogenesis of rheumatoid arthritis (RA), we used proteomic analysis to determine the protein profile in a synovial cell line, MH7A, established from patients with RA. Proteins were extracted from MH7A cells that were or were not stimulated with tumor necrosis factor‐α (TNF‐α), and then analyzed on a liquid chromatography/mass spectrometry system equipped with a unique long monolithic silica capillary. On the basis of the results of this proteomic analysis, we identified 2650 proteins from untreated MH7A cells and 2688 proteins from MH7A cells stimulated with TNF‐α. Next, we selected 269 differentially produced proteins that were detected only under TNF‐α stimulation, and classified these proteins by performing gene ontology analysis by using DAVID as a functional annotation tool. In TNF‐α‐stimulated MH7A cells, we observed substantial production of plasminogen‐activator inhibitor 2 and apoptosis‐regulating proteins such as BH3‐interacting domain death agonist, autophagy protein 5, apolipoprotein E, and caspase‐3. These results indicate that the upregulation of plasminogen‐activator inhibitor 2 and apoptosis‐regulating proteins in synovial cells in response to TNF‐α stimulation might represent a predominant factor that contributes to the pathogenesis of RA.

Optimization of poly(methyl styrene-co-bis(p-vinylbenzyl)dimethylsilane)-based capillary monoliths for separation of low, medium, and high molecular-weight analytes

Poly(methyl styrene-co-bis(p-vinylbenzyl)dimethylsilane)-based monolithic capillary columns were optimized for separation of low, medium, and high molecular-weight analytes. The morphology and consequently the chromatographic performance of these monoliths were tuned by changes in the volume-ratio of monomer to macroporogen, establishing good monolithic flow-through and retention pores. Two monoliths were prepared and analyzed by reversed-phase chromatographic separation of low molecular-weight analytes such as alkyl benzenes and β-blockers, as well as medium and high molecular-weight analytes such as peptides and proteins, respectively. The microstructure was studied by scanning electron microscopy (SEM), and by inverse-size exclusion chromatography (ISEC). Monolith 1 demonstrated a high retention of alkyl benzenes, which coeluted from the column at the washing step of absolute acetonitrile; yet this monolith established a baseline separation of 9-peptide and 8-protein mixtures. Monolith 2 demonstrated efficient separation of the three analyte groups of different molecular weights. Six alkyl benzenes and five β-blockers were base-line separated in less than 5 and 2min, respectively, with good resolution and very small values of peak width at half height. Moreover, a comparable performance of efficient separation of the 9-peptide mixture and a fast separation of 5- and 8-protein mixtures were achieved. Both monoliths were characterized by high mechanical strength, high permeability, and excellent reproducibility.

Monoliths in capillary electrochromatography and capillary liquid chromatography in conjunction with mass spectrometry.

Here, we have reviewed separation studies utilizing monolithic capillary columns for separation of compounds preceding MS analysis. The review is divided in two parts according to the used separation method, namely CEC and capillary LC (cLC). Based on our overview, monolithic CEC-MS technique have been more focused on the syntheses of highly specialized and selective separation phase materials for fast and efficient separation of specific types of analytes. In contrast, monolithic cLC-MS is more widely used and is often employed, for instance, in the analysis of oligonucleotides, metabolites, and peptides and proteins in proteomic studies. While poly(styrene-divinylbenzene)-based and silica-based monolithic capillaries found their place in proteomic analyses, the other laboratory-synthesized monoliths still wait for their wider utilization in routine analyses. The development of new monolithic materials will most likely continue due to the demand of more efficient and rapid separation of increasingly complex samples.

Electroosmotic pump-supported molecularly imprinted monolithic column for capillary chromatographic separation of nitrophenol isomers.

In this work, a novel molecularly imprinted polymer (MIP) monolithic column with integrated in-column electroosmotic pump (EOP) was designed and successfully prepared to facilitate the capillary chromatography with MIP column. A silica-based EOP was synthesized at the detection end of the MIP monolithic capillary column by so-gel to provide the hydrodynamic driven force for the capillary chromatography. Because of large surface area and low fluidic resistance of the silica monolith,a strong and steady EOF was generated by silica-based EOP, indicating that the EOP was quite compatible with MIP capillary column. With the sufficient EOF provided by EOP, the electro-driven based capillary chromatographic separation of nitrophenol isomers was achieved in 4-vinylpyridine-based MIP monolithic capillary, which was originally proved infeasible because of the EOF shortage. No significant influence upon the specific recognition of the MIP was found due to the setting of EOP after the detection window of the column. The influence of experimental parameters on the EOF such as voltage and pH value of running buffer was investigated. The column was also evaluated by capillary liquid chromatographic mode to compare with EOP-driven capillary chromatography. Higher column efficiency was obtained by EOP-driven separation with improved peak shape. The results suggested that EOP-supported technique would be a good way to solve the problem of weak EOF generation in electro-driven capillary chromatography.

TiO₂ nanoparticles functionalized monolithic capillary microextraction online coupled with inductively coupled plasma mass spectrometry for the analysis of Gd ion and Gd-based contrast agents in human urine.

In this work, a novel method of TiO2 nanoparticles (NPs) functionalized monolithic capillary microextraction (CME) online coupling with inductively coupled plasma mass spectrometry (ICPMS) was developed for the sequential determination of Gd(3+) and Gd-based contrast agents in human urine samples. The monolithic capillary was prepared by embedding anatase TiO2 NPS in the poly(methacrylic acid-ethylene glycol dimethacrylate) (MAA-EDMA) framework. The Gd(3+) and Gd-based contrast agents (such as gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) and Gd-DTPA-bismethylamide (Gd-DTPA-BMA)) display different adsorption behaviors on the prepared monolithic capillary which possesses the adsorption properties of both anatase TiO2 NPS and poly(MAA-EDMA) monolith. Under the optimized conditions, the limits of detection (LODs) were found to be 3.6, 3.2, and 4.5 ng L(-1) for Gd(3+), Gd-DTPA, and Gd-DTPA-BMA, respectively, which are the lowest up to date. The enrichment factor was 25-fold with the sample throughput of 5 h(-1). The proposed method was validated by the analysis of Gd(3+) and Gd-DTPA in the healthy human urine samples as well as Gd(3+) and Gd-DTPA-BMA in patient urine samples. It was found that only a small amount of the free Gd(3+) was released from Gd-DTPA-BMA, and accurate results could be obtained since no oxidation/reduction or subtraction is involved in this method. This method is simple, sensitive, and rapid and provides a very attractive nonchromatography strategy for the speciation of Gd(3+) and Gd-based contrast agents in urine samples.

Copper nanoparticles supported on permeable monolith with carboxylic acid surface functionality: Stability and catalytic properties under reductive conditions

This work reported on the immobilization of copper metallic nanoparticles at the interface of mercaptosuccinic acid-functionalized N-acryloxysuccinimide-based monoliths. Upon photochemically-mediated free radical copolymerization of N-acryloxysuccinimide reactive monomer with ethylene glycol dimethacrylate cross-linker, reactive monoliths were obtained. Nucleophilic substitution of the N-hydroxysuccinimide moieties with allylamine, allowed for the synthesis of an olefin-functionalized monolith, as demonstrated by Raman spectroscopy. Mercaptosuccinic acid was anchored at the surface of the porous polymeric material through photochemically-driven thiol-ene “click” addition. In a final step, adsorption of copper nanoparticles at the surface of the resulting carboxylic acid functionalized monolith was achieved via two distinct pathways. It was either realized by percolation of a suspension of pre-formed copper nanoparticles through the capillary or by in situ reduction of Cu(II)Br2 salt solution preliminary flown through the monolith. After characterization of the resulting hybrids by scanning electron microscopy and energy-dispersive X-ray spectroscopy, investigations were further pursued regarding the catalytic behavior of such hybrid materials. The possibility to reduce 2-nitrophenol into the corresponding 2-aminophenol within a few minutes via a flow-through process inside the hybrid monolithic capillary was notably successfully demonstrated.

Tuning preparation conditions towards optimized separation performance of thermally polymerized organo-silica monolithic columns in capillary liquid chromatography

Tuning of preparation conditions, such as variations in the amount of a porogen, concentration of an aqueous acid catalyst, and adjustment in polymerization temperature and time, towards optimized chromatographic performance of thermally polymerized monolithic capillaries prepared from 3-(methacryloyloxy)propyltrimethoxysilane has been carried out. Performance of capillary columns in reversed-phase liquid chromatography was assessed utilizing various sets of solutes. Results describing hydrophobicity, steric selectivity, and extent of hydrogen bonding enabled comparison of performance of hybrid monolithic columns prepared under thermal (TSG) and photopolymerized (PSG) conditions. Reduced amounts of porogen in the polymerization mixture, and prolonged reaction times were necessary for the preparation of monolithic columns with enhanced retention and column efficiency that reached to 111,000 plates/m for alkylbenzenes with shorter alkyl chains. Both increased concentration of catalyst and higher temperature resulted in faster polymerization but inevitably in insufficient time for pore formation. Thermally polymerized monoliths produced surfaces, which were slightly more hydrophobic (a methylene selectivity of 1.28±0.002 TSG vs 1.20±0.002 PSG), with reduced number of residual silanols (a caffeine/phenol selectivity of 0.13±0.001 TSG vs 0.17±0.003 PSG). However, steric selectivity of 1.70±0.01 was the same for both types of columns. The batch-to-batch repeatability was better using thermal initiation compared to monolithic columns prepared under photopolymerized conditions. RSD for retention factor of benzene was 3.7% for TSG capillaries (n=42) vs. 6.6% for PSG capillaries (n=18). A similar trend was observed for columns prepared within the same batch.

In-line coupling of an aptamer based miniaturized monolithic affinity preconcentration unit with capillary electrophoresis and Laser Induced Fluorescence detection

A composite 30-cm capillary was prepared. The head of the capillary was a 1.5-cm original and miniaturized aptamer-based monolithic affinity support that was in-line coupled to the end of the capillary used for capillary electrophoresis (CE) with laser induced fluorescence (LIF) detection. The device was used for the preconcentration, separation and quantification of ochratoxin A (OTA) as a test solute. The 1.5-cm preconcentration unit consists of a fritless affinity monolithic bonded with 5′-SH-modified oligonucleotide aptamers. A vinyl spacer was used for thiol-ene photoclick chemistry with a 5min irradiation at 365nm. Photografting allowed to confine the binding reaction to the desired silica monolithic segment, upstream the empty section of the CE capillary using an UV mask. The photografting procedure was optimized preparing 10-cm capillary monoliths for nano-LC. The retention factors of cationic solutes in ion-exchange nano-LC allowed to follow the aptamer binding on the monolith. The reproducibility of the photografting process was satisfactory with inter-capillary variation lower than 10%. The aptamer bonding density can be increased by successive graftings of 100μM aptamer concentration solution (5pmol/cm/grafting). The optimal conditions to successfully perform the in-line coupling (preconcentration, elution and separation of OTA) with the composite capillary were adjusted depending on individual requirements of each step but also insuring compatibility. Under optimized conditions, OTA was successfully preconcentrated and quantified down to 0.1pg (percolation of 2.65μL of a 40ng/L OTA solution). A quantitative recovery of OTA (93±2%) was achieved in a single elution of 30pg percolated OTA amount. The reproducibility of the overall process was satisfactory with a relative standard deviation lower than 10% with negligible non-specific adsorption. This device was applied for the preconcentration and analysis of OTA in beer and wine at the ppb level within a total analysis time of 30min.

A new SERS substrate based on silver nanoparticle functionalized polymethacrylate monoliths in a capillary, and it application to the trace determination of pesticides

We have developed a simple, sensitive and practical substrate for surface enhanced Raman scattering (SERS). It consists of a column material that is obtained by modifying the surface of (glycidyl methacrylate)-co-(ethylene dimethacrylate) capillary monoliths with silver nanoparticles. This new SERS column substrate was applied to the determination of 4-mercaptopyridine (4-Mpy) and Rhodamine 6G (R6G) to give detection limits as low as 100 and 10 pM, respectively. The calculated enhancement factor is approximately 1.2 × 108. This represents a substantial improvement over conventional colloidal substrates. The new substrate was applied to the determination of residues of the pesticide phosmet and gave a detection limit of 3 μg∙L−1, with a linear response in the 3 to 1000 μg∙L−1 concentration range (R2 = 0.995). Additionally, 0.2 mg∙kg−1 of phosmet on apples and oranges, and of 0.5 mg∙kg−1 on tea leaves were detectable via SERS using this column along with a simple extraction process. The above LODs are well below the tolerance level prescribed by National Standard of China. Thus, this simple method is highly efficient, sensitive, and affordable and introduces a SERS–based trace detection suitable for real-world applications, especially for the determination of pesticides.

Synthesis of a reactive polymethacrylate capillary monolith and its use as a starting material for the preparation of a stationary phase for hydrophilic interaction chromatography

Poly(3-chloro-2-hydroxypropyl methacrylate-co-ethylene dimethacrylate), poly(HPMA-Cl-co-EDMA) capillary monolith was proposed as a reactive starting material with tailoring flexibility for the preparation of monolithic stationary phases. The reactive capillary monolith was synthesized by free radical copolymerization of 3-chloro-2-hydroxypropyl methacrylate (HPMA-Cl) and ethylene dimethacrylate (EDMA). The mean pore size, the specific surface area and the permeability of poly(HPMA-Cl-co-EDMA) monoliths were controlled by adjusting porogen/monomer volume ratio, porogen composition and polymerization temperature. The porogen/monomer volume ratio was found as the most effective factor controlling the porous properties of poly(HPMA-Cl-co-EDMA) monolith. Triethanolamine (TEA-OH) functionalized polymethacrylate monoliths were prepared by using the reactive chloropropyl group of poly(HPMA-Cl-co-EDMA) monolith via one-pot and simple post-functionalization process. Poly(HPMA-Cl-co-EDMA) monolith reacted with TEA-OH was evaluated as a stationary phase in nano-hydrophilic interaction chromatography (nano-HILIC). Nucleotides, nucleosides and benzoic acid derivatives were satisfactorily separated with the plate heights up to 20μm. TEA-OH attached-poly(HPMA-Cl-co-EDMA) monolith showed a reproducible and stable retention behaviour in nano-HILIC runs. However, a decrease in the column performance (i.e. an increase in the plate height) was observed with the increasing retention factor. Hence “retention-dependent column efficiency” behaviour was shown for HILIC mode using the chromatographic data collected with the polymer based monolith synthesized.

Fabrication of aluminum terephthalate metal-organic framework incorporated polymer monolith for the microextraction of non-steroidal anti-inflammatory drugs in water and urine samples

Polymer monolith microextraction (PMME) based on capillary monolithic column is an effective and useful technique to preconcentrate trace analytes from environmental and biological samples. Here, we report the fabrication of a novel aluminum terephthalate metal-organic framework (MIL-53(Al)) incorporated capillary monolithic column via in situ polymerization for the PMME of non-steroidal anti-inflammatory drugs (NSAIDs) (ketoprofen, fenbufen and ibuprofen) in water and urine samples. The fabricated MIL-53(Al) incorporated monolith was characterized by X-ray powder diffractometry, scanning electron microscopy, Fourier transform infrared spectrometry, and nitrogen adsorption experiment. The MIL-53(Al) incorporated monolith gave larger surface area than the neat polymer monolith. A 2-cm long MIL-53(Al) incorporated capillary monolith was applied for PMME coupled with high-performance liquid chromatography for the determination of the NSAIDs. Potential factors affecting the PMME were studied in detail. Under the optimized conditions, the developed method gave the enhancement factors of 46–51, the linear range of 0.40–200μgL−1, the detection limits (S/N=3) of 0.12–0.24μgL−1, and the quantification limits (S/N=10) of 0.40–0.85μgL−1. The recoveries for spiked NSAIDs (20μgL−1) in water and urine samples were in the range of 77.3–104%. Besides, the MIL-53(Al) incorporated monolith was stable enough for 120 extraction cycles without significant loss of extraction efficiency. The developed method was successfully applied to the determination of NSAIDs in water and urine samples.