Polymer Monolith Microextraction Research Articles

Determination of ligustrazine in rat serum by polymer monolithic micro-extraction combined with ultra high performance liquid chromatography-tandem mass spectrometry

AbstractThis study focused on developing an effective and environmentally friendly method to measure ligustrazine in rat serum by using polymer monolith micro-extraction (PMME) technique. A poly (methacrylic acid-ethylene glycol dimethacrylate) material was used to extract ligustrazine through hydrophobic and ion-exchange interaction. Qualitative and quantitative analysis was performed by a liquid chromatography and tandem mass spectrometry. After optimization of several PMME conditions, the developed method exhibited excellent extraction performance to the ligustrazine. Good linearity was acquired ranging from 10 to 2,000 ng mL−1, and the limit of detection of the proposed method was 0.14 ng mL−1. The recoveries measured by spiking three different concentrations in rat serum ranged from 82.6 to 95.3%, and excellent precision was found with relative standard deviations (RSDs) less than 8.3% for intra-day and 9.7% for inter-day, respectively. At last, the applicability of the method was further confirmed through continuous monitoring of ligustrazine in rat serum after dosing of ligustrazine tablets to rats.

Preparation of zirconium arsenate-modified monolithic column for selective enrichment of phosphopeptides.

Protein phosphorylation is a crucial posttranslational modification for the regulation of many different biological functions. Selective enrichment of phosphopeptides from the complex biological samples is an essential step for the mass spectrometry analysis of protein phosphorylation. In this study, an arsenate functionalized monolithic column was first prepared by a single-step copolymerization of p-methacryloylaminophenylarsonic acid and ethylene dimethacrylate. Then the metal ions Zr4+ were attached onto the prepared monolithic column via metal-chelate complex formation by Zr4+ and arsenate groups. The obtained monolithic column was employed as a new sorbent for the phosphopeptide enrichment via immobilized metal affinity chromatography. Phosphopeptides analysis was realized by polymer monolith microextraction using this monolithic column coupled to both matrix-assisted laser desorption/ionization mass spectrometry and liquid chromatography-electrospray ionization tandem mass spectrometry. The proposed method exhibited a high selectivity for phosphopeptide enrichment in complex matrices, and was applied to the analysis of phosphopeptides in human serum and tryptic digests of rat brain proteins. Four phosphopeptides could be selectively captured from human serum and 2608 endogenous phosphopeptides were identified from the tryptic digests of rat brain proteins, indicating a satisfactory performance of this method for the enrichment of phosphopeptides from complex biological samples.

Online polymer monolith microextraction with in-situ derivatization for sensitive detection of endogenous brassinosteroids by LC-MS

An automatic and sensitive method which integrated polymer monolith microextraction and in-situ derivatization with liquid chromatography-mass spectrometry (PMME-ISD-LC-MS) was proposed for the quantification of endogenous brassinosteroids (BRs) in plant samples. In the described method, the anionic HIILIC monolithic column was modified with 2-methyl-4-phenylaminomethylphenylboronic acid (2-methyl-4-PAMBA) through ion exchange interaction and then used as a boronate affinity media to selectively capture, purify and derivatize BRs in crude extract through the reaction of the boronic acid group of 2-methyl-4-PAMBA and cis-diol on BRs. The BR derivatives were easily eluted by destroying the ion exchange interactions using the acidic eluting solvent, and then analyzed by LC-MS. The whole extraction and LC-MS analysis processes were automatically controlled which could be completed within 50 min. Under the optimized conditions, good linearities were obtained for six BRs with the correlation coefficients (R) ranging from 0.9953 to 0.9998. The limits of detection (LODs, S/N = 3) ranged from 0.10 to 1.29 pg mL−1. The recoveries were between 82.3% and 119.1% with the relative standard deviations (RSDs) ranging from 2.2% to 18.3%. Finally, the proposed method was applied for the quantification of endogenous BRs in various plant samples including different Oryza sativa L. cv. tissues (1.0 mg, fresh weight (FW)), Phaseolus vulgaris L. (1.0 mg FW), Vigna unguiculata (1.0 mg FW), Arabidopsis thaliana flower (1.3 mg FW).

Selective enrichment of glycopeptides based on copper tetra(N-carbonylacrylic) aminephthalocyanine and iminodiacetic acid functionalized polymer monolith.

Efficient separation and enrichment of low-abundance glycopeptides from complex biological samples is the key to the discovery of disease biomarkers. In this work, a new material was prepared by coating copper tetra(N-carbonylacrylic) aminephthalocyanine and iminodiacetic acid onto poly(glycidyl methacrylate-pentaerythritol triacrylate) monolith. The monolith was applied to polymer monolithic microextraction for specific capture of glycopeptides coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The developed monolith exhibited satisfactory efficiency for glycopeptide enrichment with high selectivity and detection sensitivity. When the tryptic digest of immunoglobulin G was used as the sample, total 24 glycopeptides were identified and the detection limit was determined as 5fmol. When the approach was applied to the analysis of glycopeptides in the mixture of bovine serum albumin and immunoglobulin G (100:1, m/m) digests, 16 glycopeptides could still be observed. Moreover, the monolith was successfully applied to the selective enrichment of glycopeptides from human serum digests, exhibiting great practicability in identifying low-abundance glycopeptides in complex biological samples.

Highly Sensitive Determination for Catecholamines Using Boronate Affinity Polymer Monolith Microextraction with In-Situ Derivatization and HPLC Fluorescence Detection

Catecholamines such as dopamine, norepinephrine and epinephrine are important neurotransmitters containing cis-diol moieties, and HPLC with fluorescence detection (HPLC-FD) has been successfully used as highly sensitive detection method for them. However, the complex matrix of biological samples is always a challenge. Boronate affinity microextraction is practical to purify and enrich cis-diol compounds. In this study, we used in-situ derivatization in boronate affinity polymer monolith microextraction (BA/PMME) to combine sample pretreatment and derivatization, then followed by HPLC-FD to develop a highly sensitive and selective determination method for catecholamines. Taking poly(3-acrylamidophenyl boronic acid-co-ethylene dimethacrylate) as BA/PMME material and TMBB-Su as labeling reagent, catecholamines could be derivatizated in polymer monolith in-situ together with the sample enrichment and purification. Comparing with commonly used solid phase extraction followed by derivatization, fewer operation steps are required and higher sensitivity was obtained with LODs as low as 0.06–0.2 nM.

A Selective Joint Determination of Salicylic Acid in Actinidia chinensis Combining a Molecularly Imprinted Monolithic Column and a Graphene Oxide Modified Electrode.

A new combination between selective polymer monolith microextraction (PMME) and sensitive differential pulse voltammetry (DPV) was developed for the determination of the phytohormone salicylic acid (SA) in Actinidia chinensis. A molecularly imprinted monolithic column (MIMC) thermally in-situ polymerized in a micropipette tip by using SA as a template, 4-vinyl pyridine (4-VP) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker in the mixed porogen of toluene and dodecanol, was employed for the microextraction of SA. The prepared MIMC was characterized by a Fourier transform infrared spectrometer (FI-TR), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). The results confirmed the binary continuous structure of the porous network. The extracted SA was determined by DPV on a graphene oxide (GO) modified electrode. The joint conditions between MIMC and DPV were investigated practically. Under the optimum conditions, SA could be determined selectively and sensitively in a linear range from 0.1 to 60.0 μg g-1. The limit of detection was 0.03 μg g-1 and the recoveries were between 86.2 and 105.2%. The proposed joint method was successfully used to determine SA in Actinidia chinensis.

Preparation of ionic liquid hybrid melamine-based covalent organic polymer functionalized polymer monolithic material for the preconcentration of synthetic phenolic antioxidants

In this study, a hybrid composite containing melamine-based covalent organic polymer (MCOP) and ionic liquid (IL) was designed and employed for the functionalization of polymer monolith. The obtained polymer monolithic material was confirmed by scanning electron microscopy, Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, and thermal gravimetric analysis. A polymer monolith microextraction (PMME) strategy was established based on the monolith for the enrichment of synthetic phenolic antioxidants, exhibiting high sensitivity, good stability and repeatability. Intra-day and inter-day relative standard deviations were both less than 10%. The developed PMME-HPLC method was applied to the preconcentration and determination of synthetic phenolic antioxidants in cosmetic samples and assessed through recovery studies. The developed polymer monolithic material had great potential as a candidate in the preconcentration field for PMME.

On-line coupling of hydrophilic ionic liquids-based polymer monolith microextraction to capillary liquid chromatography with amperometric detection: An ultrasensitive residue analysis method for glycopeptide antibiotics

A hydrophilic ionic liquids based polymer monolith microextraction (PMME) column (poly(ionic liquid-co-hydroxyethyl methacrylate-co-ethylene dimethacrylate); poly(IL-co-HEMA-co-EDMA)) was prepared for the first time in a capillary and utilized in PMME for the enrichment of glycopeptide antibiotics (GAs), followed by the online coupling analysis of capillary liquid chromatography with amperometric detection (cLC-AD). The prepared monolith exhibited large through pores and good storage stability, as well as a selective extraction machanism for GAs that was attributed to the hydrogen bonding, hydrophilic, electrostatic and π-π interactions between GAs and the imidazolium cations or hydroxyl groups on the surface of absorbent. Several experimental parameters, such as sample flow rate, composition of eluent and solvent desorption conditions, were examined to improve the extraction efficiency of PMME. Under the optimal conditions, the proposed PMME-cLC-AD method provides detection limits (S/N = 3) of 1.0–8.0 μg L−1 for three GAs, which are 1000-fold lower than those obtained by cLC-AD, with a wide linear range of 10.0–12000.0 μg L−1. It was successfully applied for the analysis of GAs residues in feed samples with good recoveries (80.3–119.1%) and satisfied intra-day/inter-day precision (<10%). Compared with LC-3Q-MS method, the proposed online approach has the merits of simple, low cost, smaller matrix interference and environmental friendly, which is demonstrated to be a feasible tool for residue analysis of peptide antibiotics in food safety application.

Application of mesoporous carbon-polymer monolith for the extraction of phenolic acid in food samples

In this study, activated carbon-organic polymer (AC-polymer) extraction columns were prepared via microwave-assisted polymerization. The AC-polymer was applied in polymer monolith microextraction (PMME) of phenolic acids (PAs) in food samples. Structural characterization using Raman and Fourier transform infrared (FTIR) spectroscopy revealed the successful incorporation of AC into polymer monolith. In contrast to neat polymer in which low extraction efficiency (17.0–57.7%) was observed, the AC-polymer (8 mg AC, 4 cm column length) afforded better extraction efficiency for PAs ranging from 75.8 to 99.8% for intra-day with less than 1.4% relative standard deviations (RSDs) and inter-day precision ranging from 74.3 to 100.1% (<2.7% RSDs). The extraction efficiency for column-to-column were found to be in the range of 72.8–100.5% (<2.0% RSDs) (n = 3). Under the optimized conditions, the AC-polymer monolithic column was successfully applied in PMME of PAs in fruit wine and cranberry juice samples at concentrations of <4.8 mg L−1 and 26.54 mg L−1, respectively.

Preparation of polymethacrylate monolith modified with cysteine for the determination of Cr(iii) ions.

In this study, a simple and rapid polymer monolith microextraction procedure was developed for the determination of Cr(iii) ions by inductively coupled plasma-atomic emission spectrometry. A monolithic column modified with cysteine was synthesized and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis, specific surface area analysis and pore size distribution analysis. The influences of analytical parameters such as sample pH, adsorption time, eluent type, and coexisting ions were examined. The limit of detection (LOD) and limit of quantification (LOQ) for Cr(iii) ions were 0.005 μg mL−1 and 0.017 μg mL−1, and the relative standard deviation (RSD) was 7.4% (n = 5). The prepared cysteine functionalized monolithic column displayed good enrichment capacity and was successfully applied to the determination of Cr(iii) ions in real samples.

Peanut agglutinin and β-cyclodextrin functionalized polymer monolith: Microextraction of IgG galactosylation coupled with online MS detection

A facile online method coupling polymer monolithic microextraction (PMME) with mass spectrometry (MS) was developed for the detection of Immunoglobulin G (IgG) galactosylation glycopeptides. A peanut agglutinin-β-cyclodextrin (PNA-β-CD) functionalized poly(hydroxyethyl methylacrylate-ethyleneglycol dimethacrylate) monolith was designed via a click reaction. Thanking to the specificity of PNA-β-CD for the targets, the material exhibited enhanced enrichment selectivity and extraction efficiency for IgG galactosylation glycopeptides. Under optimal conditions, the developed method gave a linear range of 0.005–5 pmol for IgG glycopeptides with the regression coefficient greater than 0.9990, and the detection limit of IgG galactosylation glycopeptides as low as 0.5 fmol was achieved. The PMME-MS method was applied to IgG galactosylation glycopeptides in real samples including human serum and acute myelogenous leukemia (AML) cell lysate. A series of unique IgG galactosylation glycopeptides were captured by the monolith in the complex samples, indicating satisfactory enrichment ability for IgG galactosylation glycopeptides. The quick and integrated online PMME-MS method exhibited high selectivity for IgG galactosylation, demonstrating its perspectives on the development and broad applications of MS in studying galactosylation proteins regulated biological processes.

Polyoxometalate incorporated polymer monolith microextraction for highly selective extraction of antidepressants in undiluted urine

In this work, a polyoxometalate (POM) incorporated polymer monolith microextraction (PMME) was successfully proposed and employed in the selective extraction of basic antidepressants in undiluted urine sample. This hybrid monolith exhibited strong cation-exchange interaction (SCX) with positively charged antidepressants when pH was 3.0, because of the multiple ionizable moieties on polyanionic POM. As such, antidepressants in complex sample matrices were efficiently extracted by the monolith, and the matrix effect was significantly reduced. In addition, due to the high amount of anionic POM, the monolith exhibited remarkable extraction capacities for target antidepressants ranging from 4.7 to 5.8mg/g. Further, the POM incorporated PMME was coupled with high-performance liquid chromatography-ultraviolet (HPLC-UV). Thus, antidepressants in undiluted urine sample was efficiently extracted under optimized extraction conditions online. The limits of detection (LODs) for the target antidepressants ranged from 0.7 to 1.4ng/mL, and the linear range was 5–1000ng/mL with determination coefficients (R2) higher than 0.9960. The recoveries ranged from 86.8% to 104.0% with relative standard deviations (RSDs) of 0.4–10.1%. The proposed procedure was successfully applied to determine antidepressant in human urine. Taken together, the developed method presented a new strategy for the analysis of basic drugs in undiluted urine sample, which could be used for monitoring medicines in pharmacokinetic analysis.

Preparation of a polymer monolith modified with delaminated layered double hydroxides for the microextraction of β-agonists.

In the present study, a novel poly(acrylamide-co-N-isopropylacrylamide-co-ethylene dimethacrylate) monolithic column modified with saline-modified delaminated layered double hydroxides was developed and exploited as the stationary phase in the polymer monolith microextraction of β-agonists. Transmission electron microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermal gravimetric analysis with derivative thermogravimetric determination were employed to characterize the monoliths. By coupling with high-performance liquid chromatography determinations, extraction parameters affecting the extraction efficiency, including sample volume, flow rate, sample pH, eluent volume, and eluent flow rate were investigated with an orthogonal experiment design, L16 (45 ). Results demonstrated that under the optimal experimental conditions, low limits of detection in the range of 0.025-0.280ng/mL were obtained with relative standard deviations in the range of 4.3-7.6% (intraday) and 6.7-8.8% (interday). When the developed method was applied to the analysis of β-agonists in pork samples, recovery values were obtained in the range of 80.5-108.6%.

Preconcentration of bisphenols by using calix[4]arene derivatives modified porous polymer monolith coupled with HPLC

A functionalized calix[4]arene (alkenyl@C[4]A) was introduced into the poly(butyl methacrylate-ethylene dimethacrylate) monolith inside a capillary to prepare a polymer monolith microextraction (PMME) material (poly(BMA-alkenyl@C[4]A-EDMA)).

Erratum to: Polymer monolithic column containing embedded graphene oxide sheets for sensitive determination of carbamate insecticides by HPLC

We describe a new kind of polymer monolithic column for polymer monolith microextraction (PMME) of carbamate insecticide (methomyl, carbofuran and pirimicarb) residues from water samples. The monolith was prepared inside the tip of a micropipette via thermally initiated free-radical polymerization of methacrylic acid as the monomer, ethylene glycol dimethacrylate as the cross-linker, and graphene oxide (GO) dispersed in the mixed porogens (1-propanol and 1,4-butanediol). The resulting monolith was characterized by scanning electron microscopy and IR spectrometry. The effects of sample flow rate, sample volume, sample pH, desorption solvent and flow rate on PMME were optimized. Compared to a monolith without GO, the new monolith displays higher enrichment capacity, and is reusable and stable. Following extraction, the three carbamates were quantified by HPLC. The limits of detection (for S/N = 3) for the three carbamates are in the range of 0.3–0.7 μg∙L−1, and the intra- and inter-day precisions are <5.7 %. The new monolith was successfully applied for the determination of the insecticides in various (spiked) environmental water samples, with recoveries in the range from 78.9 to 103.4 %.

Polymer monolith microextraction using poly(butyl methacrylate-co-1,6-hexanediol ethoxylate diacrylate) monolithic sorbent for determination of phenylurea herbicides in water samples

In this study, recently developed 1,6-hexanediol ethoxylate diacrylate (HEDA)-based polymeric monoliths were utilized as sorbents for efficient extraction of phenylurea herbicides (PUHs) from water samples. The HEDA-based monolithic sorbents were prepared in a fused silica capillary (0.7mm i.d., 4.5-cm long) for polymer monolith microextraction (PMME). The experimental parameters of PMME microextraction including sample loading speed, pH of sample solution, composition of elution solvent, and addition of salt were optimized to efficiently extract PUHs from environmental water samples. The extracted PUHs were determined using ultra-high performance liquid chromatography (UHPLC) with UV-photodiode array detection. The extraction recoveries for PUHs-spiked water samples were 91.1–108.1% with relative standard deviations lower than 5%. The linearity range was 0.025–25ngmL−1 for each PUH and the detection limits of PUHs were estimated at 0.006–0.019ngmL−1. In addition, good intra-day/inter-day precision (0.1–8.7%/0.2–8.9%) and accuracy (92.0–108.0%/96.5–105.2%) of the proposed method were obtained. The extraction capacity of the monolith-filled capillary was also determined to be approximately 1μg. Moreover, each monolith-filled capillary could be reused up to 8 times without carry-over. According to the European Union regulations, the allowed permissible limit of any single herbicide in drinking water is 0.1ngmL−1. This permissible level fell in the linear range examined in this study. In addition, the proposed method provided detection limits lower than the allowed permissible level, which demonstrated the feasibility of utilizing the HEDA-based monolithic sorbent to perform PMME for determining contaminants, such as PUHs, in environmental application.

Preparation of a zeolite-modified polymer monolith for identification of synthetic colorants in lipsticks

A novel zeolite-modified poly(methacrylic acid-ethylenedimethacrylate) (zeolite@poly(MAA-EDMA)) monolithic column was prepared with the in situ polymerization method and employed in polymer monolith microextraction for the separation and preconcentration of synthetic colorants combined with high performance liquid chromatography. The polymer was characterized by scanning electronmicroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermo-gravimetric analysis. Various parameters affecting the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. The method was applied to the determination of synthetic colorants in lipsticks with recoveries ranged from 70.7% to 109.7%. Compared with conventional methacrylic acid-based monoliths, the developed monolith exhibited high enrichment capacity because of the introduction of zeolites into the preparation process. The extraction efficiency followed the order: zeolite@poly(MAA-EDMA)>poly(MAA-EDMA)>direct HPLC analysis.

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.

Just dip it: online coupling of "Dip-it" polymer monolith microextraction with plasma assisted laser desorption ionization mass spectrometry.

A polymer monolith microextraction (PMME) procedure coupled to plasma assisted laser desorption ionization mass spectrometry (PMME-PALDI-MS) was developed for rapid and organic solvent-free trace analysis. The extraction device used a "Dip-it" sampler coated with a MWNT incorporated monolith, and the analytes adsorbed on monoliths were effectively desorbed by laser, improving detection sensitivity.

Determination of Lomefloxacin and Gatifloxacin in Urine by High Performance Liquid Chromatography with Polymer Monolith Microextraction

Determination of Lomefloxacin and Gatifloxacin in Urine by High Performance Liquid Chromatography with Polymer Monolith Microextraction