2D-HPLC-MS Technology Combined with Molecular Network for the Identification of Components in Tibetan medicine Aconitum pendulum.

In this study, a comprehensive approach was employed, utilizing 2D-HPLC-MS technology in conjunction with the molecular network to unravel the intricate chemical composition of the Tibetan medicinal plant APB. Through the implementation of 2D-HPLC, enhanced separation of complex mixtures was achieved, enabling the isolation of individual compounds for subsequent analysis. The molecular network approach further aided in elucidating structural relationships among these compounds, contributing to the determination of potential bioactive molecules. This integrated strategy efficiently identified a wide array of chemical components present within the plant. The findings revealed a diverse spectrum of chemical constituents within APB, including alkaloids, among others. This research not only advances understanding of the phytochemical profile of this traditional Tibetan medicine but also provides valuable insights into its potential therapeutic properties. The integration of 2D-HPLC-MS and molecular network proves to be a powerful tool for systematically exploring and identifying complex chemical compositions in herbal medicines, paving the way for further research and development in the field of natural product discovery.

Synthesis of gem-Difluorinated 1,4-Dienes via Nickel-Catalyzed Three-Component Coupling of (Trifluoromethyl)alkenes, Alkynes, and Organoboronic Acids.

Herein, a nickel-catalyzed defluorinative three-component coupling of trifluoromethyl alkenes, internal alkynes, and organoboronic acids is presented. The protocol provides a highly efficient and selective route for the synthesis of structurally diverse gem-difluorinated 1,4-dienes under mild conditions. Mechanistic studies suggest that C-F bond activation proceeds probably through the oxidative cyclization of trifluoromethyl alkenes with Ni(0) species, sequential addition to alkynes, and ß-fluorine elimination.

Enhancing the compatibility of normal-phase chromatography x reversed-phase chromatography by combination of low-temperature sensitive aqueous-phase compatible normal- phase chromatography and at-column dilution modulation.

The nearly opposite retention mechanism in the two-dimensional liquid chromatography (2D-LC), which combines normal phase liquid chromatography (NPLC) and reversed phase liquid chromatography (RPLC), shows extremely high orthogonality and theoretical peak capacity. However, peak breakthrough and peak distortion caused by the highly incompatible 2D mobile phases counteracts the advantages offered by high orthogonality. To address this difficulty, this study proposes a comprehensive two-dimensional NPLC × RPLC integrating temperature-sensitive aqueous-phase compatible normal-phase chromatography (TSACNPLC) and at-column dilution modulation (ACDM). The proposed 2D-LC system uses an aqueous-miscible acetonitrile/methanol eluent in the 1st D NPLC, instead of an aqueous-phase immiscible eluent, such as n-hexane/methanol, to increase the miscibility with the RP mobile phase system. Additionally, the system exploits temperature-sensitive retention behavior to enhance the retention ability of aqueous-phase compatible NPLC. To verify the feasibility of the proposed 2D-LC, this study selected three multi-component samples with mid-to-low polarity, including ethoxylated (n ≈ 6) bisphenol A (BPA-6EO), ethoxylated (n ≈ 6) tristearylphenol (TSP-6EO), and safflower methanol extract. Next, the effectiveness of the constructed 2D-LC was systematically investigated, including low temperature-induced retention enhancement of NPLC, overcoming solvent incompatibility by ACDM, and optimization of 2 D separation conditions, was systematically investigated.

Online high-pH reversed-phase liquid chromatography × low-pH reversed-phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension for the analysis of alkaloids in Macleaya cordata (willd.) R. Br.

An online high-pH reversed-phase liquid chromatography× low-pH reversed-phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension was constructed to separate and identify alkaloids from Macleaya cordata (willd.) R. Br. The modulation was performed by using a dual second dimensional columns interface combined with a make-up dilution pump, which is responsible for dilution and neutralization of the first dimensional effluent, and the dual second dimensional columns integrated the trapping and the separation function to reduce the second dimension system dead volume. Taking advantage of the dissociable characteristics of alkaloids, mobile phases with different pH values were applied in the first dimension (pH 9.0) and the second dimension (pH 2.6) to improve the orthogonality of two-dimension separation. Besides, the pulse elution gradient in first dimension and second dimensional gradient were carefully optimized and much better separation was achieved compared to the separation with the traditional two-dimensional liquid chromatography approach. Finally, mass measurement was performed for alkaloids in M. cordata (willd.) R. Br. by coupling proposed two-dimensional liquid chromatography system with triple quadrupole mass spectrometry, and 39 alkaloids were successfully identified by comparing the obtained result with the former reported results.

Application of the new at-column dilution (ACD) modulator for the two-dimensional RP×HILIC analysis of Buddleja davidii.

The focus of this study was the analysis of the complex chemical composition from different parts of Buddleja davidii, whose species are commonly known as ornamental plants and herbal medicines in many countries. As an herbal medicine, it has been utilized for stroke treatments, headache, wound healing, neurological disorder, etc. However, the understanding of its chemical matrices is still insufficient. Therefore, an online two-dimensional reversed phase liquid chromatography x hydrophilic interaction liquid chromatography (RPLCxHILIC) system coupled with mass spectrometry was applied for further detailed investigation of the chemical constituents in Buddleja dividii. In this two-dimensional liquid chromatography (2D-LC) method, a new at-column dilution (ACD) modulator was introduced in the 2D-LC system to solve the incompatibility problem of the mobile phase between two dimensions, which resulted in a 2D-LC analysis with high orthogonality. For the root extract, as one of the analyzed samples, the optimization of the 1D and 2D gradients was carried out carefully. With this new modulator, much better peak separation and better peak shape were achieved compared to two-dimensional liquid chromatography system using a traditional standard (TS) modulator. With a similar approach, the other four parts of Buddleja davidii were well separated. Comparing the different analyzed parts, flowers and leaves showed the most complex profiles. MS and MS/MS data were obtained successfully, which demonstrated the potential of the proposed RPLCxHILIC-MS system in the constituents' analysis of herbal medicine. However, due to the lack of reported reference information, 24 compounds could be tentatively identified.

Synthesis of a poly(sulfobetaine-co-polyhedral oligomeric silsesquioxane) hybrid monolith via an in-situ ring opening quaternization for use in hydrophilic interaction capillary liquid chromatography.

An in-situ approach is described for synthesis of poly(sulfobetaine-co-polyhedral oligomeric silsesquioxane) [poly(sulfobetaine-co-POSS)] that can be used in a hybrid monolithic column as a hydrophilic liquid chromatography (HILIC) stationary phase. Synthesis involves (a) radical polymerization of octa(propyl methacrylate)-polyhedral oligomeric silsesquioxane (MA-POSS) and organic monomers such as dimethylaminopropyl methacrylate or vinyl imidazole, and (b) in-situ ring-opening quaternization between 1,4-butane sultone and the organic monomers. The sulfobetaine groups are generated in-situ monolith. This obviates the need for synthesis of sulfobetaine monomer previously. The pore size and permeability of the material can be tuned by using a binary porogenic system (polyethyleneglycol 600 and acetonitrile) and via the composition of the polymerization mixture. The optimized hybrid monolith owns its merits to the presence of POSS and sulfobetaine groups with good mechanical stability, the lack of residual silanol groups, and adequate hydrophilicity. The column filled with the monoliths was evaluated as a stationary phase for HILIC. Several kinds of polar compounds (including nucleosides, bases, phenols, aromatic acids and amides) were separated by using mobile phases with high organic solvent fractions in capillary liquid chromatography. Graphical abstractAn in-situ approach is described for synthesis of poly(sulfobetaine-co-polyhedral oligomeric silsesquioxane) hybrid monolithic column for use in hydrophilic liquid chromatography. The optimized monolith owns good mechanical stability, the lack of residual silanol groups and adequate hydrophilicity. Baseline separation of several kinds of polar compounds is achieved on the column. MA-POSS: octa(propyl-methacrylate) polyhedral oligomeric silsesquioxane; DMAEMA: dimethylaminoethyl methacrylate; AIBN: azodiisobutyronitrile. Poly(DMABS-co-POSS): poly(N-(4-sulfobutyl)-N-methacryloxypropyl- N,N-dimethylammonium-betaine-co-polyhedral oligomeric silsesquioxane).

Development of an At-Column Dilution Modulator for Flexible and Precise Control of Dilution Factors to Overcome Mobile Phase Incompatibility in Comprehensive Two-Dimensional Liquid Chromatography.

With the combination of different mechanisms, two-dimensional liquid chromatography has brought revolutionary changes compared to the traditional one-dimensional separation, which dramatically improve the peak capacity in separation and meet the ever-increasing demand for the analysis of complex samples in different research fields, such as chemistry, medicine, etc. However, the incompatibilities between two columns due to the transport of the large sample volume and the solvent effect always limit the wide use of two-dimensional liquid chromatography. In order to resolve this problem an at-column dilution (ACD) modulator was established to overcome the solvent incompatibility in the orthogonal combination within the comprehensive two-dimensional liquid chromatography. This interface is modified from normal two-dimensional interfaces by an additional transfer pump, which realize the at-column dilution without a flow split during the transportation. Moreover, with the control of the transfer flow and the second-dimensional gradient flow, it is able to precisely regulate the at-column dilution factor and conveniently optimize the separation conditions in both dimensions. In this work, a systematic research has been done between the setups with/without the at-column interface in the combination of reversed-phase liquid chromatography and hydrophilic interaction chromatography (RPLC × HILIC) and HILIC × RPLC, which proved that the at-column interface is able to resolve the solvent conflict problem very well. Furthermore, red ginseng was chosen as a real sample to investigate the applicability of the at-column dilution modulator for comprehensive two-dimensional chromatography with high orthogonality.

Pulsed elution modulation for on-line comprehensive two-dimensional liquid chromatography coupling reversed phase liquid chromatography and hydrophilic interaction chromatography.

In this work, a reversed phase liquid chromatography (RPLC) coupling to hydrophilic interaction chromatography (HILIC) system has been constructed, combining with pulsed elution reversed phase liquid chromatography (PE-RPLC) and HILIC to comprehensively analyze P. ginseng root extract, which is rich in saponins. By the application of pulsed elution (PE) modulation technique, the proposed RPLC × HILIC system allows the chromatographic separation to be optimized independently in both dimensions. In the first dimension (1D), PE modulation is achieved by the separation of a complex mixture, such as P. ginseng root extract, with a PE gradient. This PE gradient contains a set of pulses where the solvent strength increases gradually. Thus, the modulation of 1D eluent is realized by stepwise-pulse fractionation, rather than by a traditional two-dimensional interface. Furthermore, the number of fractions and the fractionated period can be regulated independently, which leads to independent adjustment of the separation cycle in the second dimension (2D) separation without the loss of D1 separation efficiency. To overcome the inherent solvent incompatibility of RPLC × HILIC, we introduced a newly developed trapping interface, equipped with bypass. The result indicates excellent separation of saponins in P. ginseng root extract. Compared with the traditional modulation method, the proposed RPLC × HILIC system has extreme flexibility, those modulation time could be regulated in a large range without re-optimizing the 1D PE gradient. Worthily mentioned, the proposed RPLC × HILIC system shows excellent orthogonality, and 20% more peaks could be obtained with current method compared to the traditional value based modulation method. Independent regulation of both dimensions could enable the proposed modulation method to be widely applied for complex samples analysis in ordinary laboratory.

The fabrication of poly (polyethylene glycol diacrylate) monolithic porous layer open tubular (mono-PLOT) columns and applications in hydrophilic interaction chromatography and capillary gas chromatography for small molecules.

The easy shrinkage and swelling of polymer monolithic column when exposed to mobile phase with different polarity is a problem that cannot be ignored. To overcome this drawback, a convenient aqueous two-phase polymerization approach was used to prepare poly (polyethylene glycol diacrylate, PEGDA) monolithic porous layer open tubular (mono-PLOT) columns (150 µm). The poly(PEGDA) mono-PLOT column with homogeneous polymer porous layer was synthesized successfully. A maximum plate number of 41,500 plates per meter for allyl thiourea was obtained under a velocity of 1.8 mm/s. Several kinds of polar molecule were separated on the proposed mono-PLOT column and a typical hydrophilic interaction retention mechanism was observed. High speed separation of benzoic acids was also carried out, baseline separation of five benzoic acids was successfully achieved within 5 min with a 70 cm mono-PLOT column at 50°C. Furthermore, the resulting PLOT column was also successfully applied to separate standard analytes of three DNA oxidative damage products and RNA-modified nucleosides and four chlorophenols. At last, the column could separate alcohols, alkanes, and aromatic isomers via GC. It had more than 20,000 plates per meter for butanol - higher than commercial coatings open tubular columns.

The preparation of a poly (pentaerythritol tetraglycidyl ether-co-poly ethylene imine) organic monolithic capillary column and its application in hydrophilic interaction chromatography for polar molecules.

An easy single-step thermal treatment "one-pot" approach for the preparation of poly (pentaerythritol tetraglycidyl ether-co-poly ethylene imine) organic monolithic capillary columns was developed successfully. The column was prepared by the epoxy-amine ring-opening polymerization of pentaerythritol tetraglycidyl ether (PTE) with poly (ethylene imine) (PEI) using acetonitrile (ACN) and polyethylene glycol 600 (PEG 600) as the porogenic system at 60 °C for 12 h. The obtained monolith was homogeneous and permeable. It achieved the high-efficiency separation of polar molecules including amides, nucleosides, bases, phenols, and benzoic acids in capillary liquid chromatography (cLC). The highest column efficiency reached ca. 101,000 plates/m (for guanine) on monolith poly(PTE-co-PEI) at 0.64 mm/s, and satisfactory chromatographic performance with column efficiencies ranged from 45,500 to 97,000 plates/m was achieved for the four amides. A typical hydrophilic interaction liquid chromatography (HILIC) retention mechanism was observed with high organic solvent contents (>60% ACN). Also, the polymer-based monolithic column was successfully applied to separate the tumor markers. Furthermore, the poly(PTE-co-PEI) monolith could be easily modified with 1, 2-epoxydodecane, which reacted with the amino groups presented on the surface of the poly(PTE-co-PEI) monolith. Hydrophobic interactions were observed during the separation of alkylbenzenes and anilines on the post-modified poly(PTE-co-PEI) monolith. Together, these results confirm the feasibility of the epoxy-amine ring-opening polymerization reaction during the fabrication of a monolithic column with high efficiency for cLC applications.

Orthogonal strategy development using reversed macroporous resin coupled with hydrophilic interaction liquid chromatography for the separation of ginsenosides from ginseng root extract.

Ginsenosides have been widely conceded as having various biological activities and are considered to be the active ingredient of ginseng. Nowadays, preparative high-performance liquid chromatography is considered to be a highly efficient method for ginseng saponins purification and preparation. However, in the process of practical application, due to the complex and varied composition of natural products and relatively simple pretreatment process, it is likely to block the chromatographic column and affect the separation efficiency and its service life. In this work, an orthogonal strategy was developed; in the first-dimension separation, reverse-phase macroporous resin was applied to remove impurities in ginseng crude extracts and classified ginseng extracts into protopanaxatriol and protopanaxadiol fractions. In the second-dimension separation, the obtained fractions were further separated by a preparative hydrophilic column, and finally yielded 11 pure compounds. Eight of them identified as ginsenoside Rh1 , Rg2 , Rd, Rc, Rb2 , Rb1 , Rg1 , and Re by standards comparison and electrospray ionization mass spectrometry. The purity of these ginsenosides was assessed by high-performance liquid chromatography with UV detection.

The synthesis of Gemini-type sulfobetaine based hybrid monolith and its application in hydrophilic interaction chromatography for small polar molecular.

In this work, a novel Gemini-type sulfobetaine-based hybrid monolith was fabricated by co-polymerization of a homemade Gemini-type sufobetaine, 1,3-bis (N-(3-sulfopropyl)-N-(methacrylic acid-2-hydroxy propyl ester)-N-methyl ammonium)-propane (BSMMP) with vinyltrimethoxysilane (VTMS) and tetramethoxysilane (TMOS) in the presence of 2'-azobis (2-methylpropionamidine) dihydrochloride (V50) as initiator. The recipe of pre-copolymerization solution for monolith preparation was optimized carefully, and the resulting monolith was characterized by scan electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR) and thermal gravimetry analysis (TGA). The results indicated that the optimized monolith possess homogeneous bio-continue pore structure, and a relatively high proportion of the sulfobetaine groups was successfully introduced into the monolith. The results from permeability test shows that the proposed monoliths have excellent permeability within both water rich mobile phase and acetonitrile rich mobile phase, due to the rigid inorganic framework of hybrid monolith. Results showed that the relative standard deviations (RSDs) of run-to-run, column-to-column and batch-to-batch were less than 1.9%, 3.7% and 6.2%, respectively. The lowest plate height value of the column for thiourea was less than 10µm. Furthermore, separating the polar small molecules including nucleosides, the base species, the phenols and the amides were performed within 14min, 22min 18min and 9min on the prepared monolith, respectively, good separation effect on these polar small molecules was found, and remarkable hydrophilic retention behavior was observed when an acetonitrile rich mobile phase was applied, attributing to the existence of strong polar Gemini-type sulfobetaine groups. Finally, the potential application of the resulting monolith in complex sample was successfully demonstrated by separating a BSA digest in gradient elution mode.

The synthesis of weak acidic type hybrid monolith via thiol-ene click chemistry and its application in hydrophilic interaction chromatography.

In this work, a porous structure and good permeability monolithic column was polymerized in UV transparent fused-silica capillaries via photo-initiated thiol-ene click polymerization of 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (TMTVS), pentaerythritol tetra(3-mercaptopropionate)(PETMP), itaconic acid, respectively, in the presence of porogenic solvents (tetrahydrofuranand methanol) and an initiator (2,2-dimethoxy-2-phenylacetophenone) (DMPA) within 30 min. The physical properties of this monolith were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and nitrogen adsorption/desorption measurements. For an overall evaluation of the monolith in chromatographic application, separations of polycyclic aromatic hydrocarbons (PAHs), phenols, amides and bases were carried out. The column efficiency of this monolith could be as high as 112 560 N/m. It also possesses a potential application in fabrication of monoliths with high efficiency for c-LC. In addition, the resulting monolithic column demonstrated the potential use in analysis of environment waters.

The synthesis of surface-glycosylated porous monolithic column via aqueous two-phase graft copolymerization and its application in capillary-liquid chromatography.

A facile, flexible process was developed for the preparation of surface-glycosylated porous monolithic columns via aqueous two-phase graft copolymerization of polyethylene glycol diacrylate (PEGDA) and water-soluble dextran (dextran sulfate). The formation of poly(PEGDA) porous skeletons and surface glycosylation were achieved via a one-step process without pre-modification of the dextran. The synthesis conditions were thoroughly optimized. The optimal monolithic column exhibited a large dry state surface area (greater than 400m2/g), and it was evaluated as a hydrophilic liquid chromatography (HILIC) stationary phase. A typical HILIC mechanism was observed at high organic solvent content (≥65% acetonitrile). In addition, the resulting monolithic column demonstrated the potential use in analysis of complex biological sample and enviroment water.

Facile "one-pot" synthesis of poly(methacrylic acid)-based hybrid monolith via thiol-ene click reaction for hydrophilic interaction chromatography.

A novel sol-gel "one-pot" approach in tandem with a radical-mediated thiol-ene reaction for the synthesis of a methacrylic acid-based hybrid monolith was developed. The polymerization monomers, tetramethoxysilane (TMOS) and 3-mercaptopropyl trimethoxysilane (MPTS), were hydrolyzed in high-concentration methacrylic acid solution that also served as a hydrophilic functional monomer. The resulting solution was then mixed with initiator (2, 2'-azobis (2-methylpropionamide) dihydrochloride) and porogen (urea, polyethylene glycol 20,000) in a capillary column and polymerized in water bath. The column had a uniform porous structure and a good permeability. The evaluation of the monolith was performed by separation of small molecules including nucleosides, phenols, amides, bases and Triton X-100. The calibration curves for uridine, inosine, adenosine and cytidine were determined. All the calibration curves exhibited good linear regressions (R(2)≥0.995) within the test ranges of 0.5-40µg/mL for four nucleosides. Additionaliy, atypical hydrophilic mechanism was proved by elution order from low to high according to polarity retention time increased with increases in the content of the organic solvent in the mobile phase. Further studies indicated that hydrogen bond and electrostatic interactions existed between the polar analytes and the stationary phase. This was the mechanism of retention. The excellent separation of the BSA digest showed good hydrophility of the column and indicated the potential in separation of complex biological samples.

Automatic and integrated micro-enzyme assay (AIµEA) platform for highly sensitive thrombin analysis via an engineered fluorescence protein-functionalized monolithic capillary column.

Nowadays, large-scale screening for enzyme discovery, engineering, and drug discovery processes require simple, fast, and sensitive enzyme activity assay platforms with high integration and potential for high-throughput detection. Herein, a novel automatic and integrated micro-enzyme assay (AIµEA) platform was proposed based on a unique microreaction system fabricated by a engineered green fluorescence protein (GFP)-functionalized monolithic capillary column, with thrombin as an example. The recombinant GFP probe was rationally engineered to possess a His-tag and a substrate sequence of thrombin, which enable it to be immobilized on the monolith via metal affinity binding, and to be released after thrombin digestion. Combined with capillary electrophoresis-laser-induced fluorescence (CE-LIF), all the procedures, including thrombin injection, online enzymatic digestion in the microreaction system, and label-free detection of the released GFP, were integrated in a single electrophoretic process. By taking advantage of the ultrahigh loading capacity of the AIµEA platform and the CE automatic programming setup, one microreaction column was sufficient for many times digestion without replacement. The novel microreaction system showed significantly enhanced catalytic efficiency, about 30 fold higher than that of the equivalent bulk reaction. Accordingly, the AIµEA platform was highly sensitive with a limit of detection down to 1 pM of thrombin. Moreover, the AIµEA platform was robust and reliable to detect thrombin in human serum samples and its inhibition by hirudin. Hence, this AIµEA platform exhibits great potential for high-throughput analysis in future biological application, disease diagnostics, and drug screening.

Direct analysis of quaternary alkaloids by in situ reactive desorption corona beam ionization MS.

The direct detection of quaternary alkaloids by atmospheric pressure chemical ionization (APCI)-base ambient MS is difficult because of their poor volatility. In this study, a reactive protocol was developed for the in situ determination of quaternary alkaloids using desorption corona beam ionization (DCBI) mass spectrometry (MS). The model compounds of 8 quaternary alkaloids including sanguinarine, chelerythrine, cyclanoline, nitidine, coptisine, jatrorrhizine, berberine, palmatine and 2 tertiary alkaloids including protopine and allocryptopine were investigated in different states such as on a polytetrafluoroethylene (PTFE) plate, in raw herbal materials, and in silica gel. After various reactive reagents were studied, the mixture of saturated aqueous NaOH solution and CH3OH solvent (3 : 7, v/v) was selected as the optimized reactive reagent for the reactive DCBI-MS detection. All the target molecules can be detected with high sensitivity. On a PTFE plate the limits of detection were 0.0795, 0.1060, 0.4860, 0.9665, 0.8879, 0.3987, 0.5557, 0.4591, 0.0889, and 0.1929 mg L(-1) for sanguinarine, chelerythrine, cyclanoline, nitidine, coptisine, jatrorrhizine, berberine, palmatine, protopine, and allocryptopine, respectively. The reactive protocol was also applied to the direct detection of raw herbal materials and thin layer chromatography successfully.

Improved sulfoalkylbetaine-based organic-silica hybrid monolith for high efficient hydrophilic interaction liquid chromatography of polar compounds.

A novel sulfoalkylbetaine-based zwitterionic organic-silica hybrid monolith was synthesized by using 3-dimethyl-(3-(N-methacrylamido) propyl) ammonium propane sulfonate (DMMPPS, neutral sulfoalkyl-betaine monomer). The added amount of zwitterionic monomer was significantly increased when DMMPPS was used instead of the conventionally used acidic sulfoalkyl-betaine monomer, that is, the N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium betaine, and this led to a significantly improved hydrophilicity of the monolith. The DMMPPS-based organic-silica hybridmonolith exhibited good mechanical stability and excellent separation performance. About ∼20 mµ plate height (corresponding to column efficiency of ∼50,000 plates/m) was obtained for nucleoside at the linear velocity of 1 mm/s. The proposed monolithic column was successfully applied to separate purines/pyrimidines, nucleotides, and tryptic digest of bovine hemoglobin in a nano-HILIC mode, and the results demonstrated that such monolith has the potential for separation of a variety of hydrophilic substances.

Magnetic solid-phase extraction based on tetrabenzyl modified Fe3O4 nanoparticles for the analysis of trace polycyclic aromatic hydrocarbons in environmental water samples.

A novel sorbent for magnetic solid-phase extraction, 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane (TBCD) modified magnetic nanoparticles, was synthesized in this work. The four benzyl groups of TBCD provide the Fe3O4-TBCD nanoparticles with strong adsorption capacity for polycyclic aromatic hydrocarbons (PAHs) due to their π-π stacking interaction, which increases selectivity of the synthesized material to target analytes. The prepared material was characterized by scanning electron microscopy, X-ray diffraction patterns, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The results indicated that the Fe3O4-TBCD nanoparticles were successfully prepared, and the particles were homogeneous nanospheres with excellent magnetic properties. Based on the optimized extraction conditions, a rapid and effective method was developed for the pre-concentration of PAHs from environmental water samples by combination with high performance liquid chromatography (HPLC). Satisfactory precision and accuracy of the developed method were obtained in a low concentration range of 0.3 ng L(-1) to 1.2 × 10(3) ng L(-1). This method produced lower limits of detection in the range of 3.0 × 10(-2) ng L(-1) to 1.2 ng L(-1). The high pre-concentration rate and efficiency of the method ensure its successful application in extraction of trace PAHs from large volumes of environmental water samples. The extraction recoveries in environmental water samples ranged from 81.1% to 115.5% with the relative standard deviations (n = 5) less than 10%.

Preparation of a polyhedral oligomeric silsesquioxane-based perfluorinated monolithic column.

A monolithic column with high affinity to fluorous compounds was prepared using a polyhedral oligomeric silsesquioxane (POSS) reagent as the cross-linker and pentadecafluorooctyl methacrylate (PDFOMA) as the functionality monomer. The pore properties and permeability could be tuned by the composition of the polymerization mixture. The characterization and evaluation results revealed that the obtained POSS-PDFOMA hybrid monolith owned the merits of POSS and PDFOMA with good mechanical stability, no residual silanol and high affinity to fluorous compounds. A series of perfluoroalkyl methacrylates were baseline resolved on the optimized monolithic column under isocratic elution of 70% acetonitrile aqueous solution. Such a resolution could not be achieved on a silica-based C18 monolithic column. A column efficiency of 30000N/m was observed. In addition, several perfluoroalkyl sulfonates were also baseline separated on the fluorous monolith applying 0.1% (v/v) acetic acid aqueous solution containing 75% acetonitrile as mobile phase without the addition of ammonium.