Hai-Bo He

Mesostructured Nanomagnetic Polyhedral Oligomeric Silsesquioxanes (POSS) Incorporated with Dithiol Organic Anchors for Multiple Pollutants Capturing in Wastewater

A functionalizable organosiliceous hybrid magnetic material was facilely constructed by surface polymerization of octavinyl polyhedral oligomeric silsesquioxane (POSS) on the Fe3O4 nanoparticles. The resultant Fe3O4@POSS was identified as a mesoporous architecture with an average particle diameter of 20 nm and high specific surface area up to 653.59 m(2) g(-1). After it was tethered with an organic chain containing dithiol via thiol-ene addition reaction, the ultimate material (Fe3O4@POSS-SH) still have moderate specific area (224.20 m(2) g(-1)) with almost identical porous morphology. It turns out to be a convenient, efficient single adsorbent for simultaneous elimination of inorganic heavy metal ions and organic dyes in simulate multicomponent wastewater at ambient temperature. The Fe3O4@POSS-SH nanoparticles can be readily withdrawn from aqueous solutions within a few seconds under moderate magnetic field and exhibit good stability in strong acid and alkaline aqueous matrices. Contaminants-loaded Fe3O4@POSS-SH can be easily regenerated with either methanol-acetic acid (for organic dyes) or hydrochloric acid (for heavy metal ions) under ultrasonication. The renewed one keeps appreciable adsorption capability toward both heavy metal ions and organic dyes, the removal rate for any of the pollutants exceeds 92% to simulate wastewater with multiple pollutants after repeated use for 5 cycles. Beyond the environmental remediation function, thanks to the pendant vinyl groups, the Fe3O4@POSS derived materials rationally integrating distinct or versatile functions could be envisaged and consequently a wide variety of applications may emerge.

HPLC separation of positional isomers on a dodecylamine-N, N-dimethylenephosphonic acid modified zirconia stationary phase

The chromatographic performance of a new zirconia stationary phase (DPZ) modified with dodecylamine-N,N-dimethylenephosphonic acid (DDPA) is studied by using positional isomers as probes. The DDPA modified zirconia via one phosphonic group has a polar inner-layer and a non-polar outer-layer on its surface. The alkyl chain of outer-layer provides the hydrophobic interaction, while the polar inner-layer that consists of an amine group and a free phosphonic group provided dipolar and ion-exchange/columbic repellent interaction sites. The effects of methanol content, ionic strength and pH of mobile phase on capacity factors of the solutes are studied in detail, and baseline separations of toluidine, nitroaniline, aminophenol, dihydroxybenzene, and nitrophenol isomers were achieved on the new zirconia stationary phase. In addition, retention mechanism of the isomers on the DDPA-modified zirconia stationary phase is also proposed.

Multiresidue determination of (fluoro)quinolone antibiotics in chicken by polymer monolith microextraction and field-amplified sample stacking procedures coupled to CE-UV.

Simultaneous determination of 9 (fluoro)quinolone antibiotics (FQs) was accomplished by capillary electrophoresis-ultraviolet (CE-UV) based on poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-EGDMA) monolith microextraction (PMME) coupled with on-line preconcentration technique of field-amplified sample stacking (FASS). The effects of composition of the acid and organic solvent in the sample solution, sampling time, and voltage on the efficiency of the sample stacking have been systematically investigated. Several parameters that influence extraction efficiency for PMME such as pH of sample solution, extraction volume, and wash and desorption conditions were optimized. In the proposed method, a substantial increase in sensitivity for all the FQs tested was achieved by the combination of PMME procedure with on-line preconcentration of FASS prior to CE analysis. Good linearities were obtained for the 9 tested FQs with the correlation coefficients (R) above 0.9954. The limits of detection (S/N=3) were found to be 2.4-34.0 ng g(-1) and the recoveries ranged from 81.2 to 100% with relative standard deviations less than 11.3%. The proposed PMME-FASS-CE method was applied to the determination of FQs residues in chicken samples.

Fabrication of enrofloxacin imprinted organic-inorganic hybrid mesoporous sorbent from nanomagnetic polyhedral oligomeric silsesquioxanes for the selective extraction of fluoroquinolones in milk samples.

This paper reports a nanomagnetic polyhedral oligomeric silsesquioxanes (POSS)-directing strategy toward construction of molecularly imprinted hybrid materials for antibiotic residues determination in milk samples. The imprinted polymeric layer was facilely obtained through the copolymerization of active vinyl groups present on the nanomagnetic POSS (Fe3O4@POSS) surface and functional monomer (methacrylic acid) binding with template (enrofloxacin). Herein, the octavinyl POSS acted as not only the building blocks for hybrid rigid architectures but also the cross-linker for the formation of effective recognition sites during the imprinting process. The molecularly imprinted Fe3O4@POSS nanoparticles (Fe3O4@MI-POSS) demonstrated much higher adsorption capacity and selectivity toward enrofloxacin molecules and its analogs than the non-imprinted Fe3O4@POSS (Fe3O4@NI-POSS) materials. The imprinted particles were applied as a selective sorbent in solid-phase extraction focusing upon sample pretreatment in complex matrices prior to chromatographic analysis. The three FQs (ofloxacin, enrofloxacin, danofloxacin) could be selectively extracted from the biological matrix, while the matrix interferences were effectively eliminated simultaneously under the optimum extraction conditions. A simple, rapid and sensitive method based on the Fe3O4@MI-POSS material combined with HPLC-UV detection was then established for the simultaneous determination of three FQs from milk samples. The average recoveries of the three FQs were in the range of 75.6-108.9%. The relative standard deviations of intra- and inter-day ranging from 2.91 to 8.87% and from 3.6 to 11.5%, respectively. The limits of detections (S/N=3) were between 1.76 and 12.42 ng mL(-1). It demonstrates the effectiveness of trace analysis in complicated biological matrices utilizing magnetic separation in combination with molecularly imprinted solid-phase extraction, the rich chemistry of POSS makes it possible to be an ideal platform for generating molecular imprinted hybrid materials is also exhibited.

Automated analysis of non-steroidal anti-inflammatory drugs in human plasma and water samples by in-tube solid-phase microextraction coupled to liquid chromatography-mass spectrometry based on a poly(4-vinylpyridine-co-ethylene dimethacrylate) monolith

A weak anion exchange polymer monolith based on poly(4-vinylpyridine-co-ethylene dimethacrylate) (poly(VP-co-EDMA)) was prepared in the capillary. The use of polyethylene glycol (PEG) as porogens and EDMA as crosslinking monomers helps to increase the specific surface area and enhance hydrophobicity of the target monolith. The monolith exhibited satisfactory permeability, high mechanical strength and good stability in aqueous buffer. The potential application of the monolith as extraction medium in complicated samples has been demonstrated by in-tube solid-phase microextraction (in-tube SPME) of three non-steroidal anti-inflammatory drugs (NSAIDs) (ketoprofen, fenbufen and ibuprofen) in human plasma and environmental water followed by on-line liquid chromatography-mass spectrometry (LC-MS) analysis. Integration of the sample extraction, LC separation and MS detection into a single system allowed for direct analysis of the NSAIDs in diluted plasma or environmental water sample, which facilitates the realization of automation of the sampling, extraction, separation and detection within a short period of time. The results showed that the limits of quantitation (S/N = 10) for the three NSAIDs were 6.70–15.9 ng mL−1 in human plasma and 0.65–1.87 ng mL−1 in water from East Lake. And the recoveries of the three NSAIDs spiked in human plasma and water from East Lake were from 88.17% to 112.48%, with relative standard deviations less than 13.87%. Compared to previously reported off-line sample extraction and conventional LC methods, the newly developed automated in-tube SPME/HPLC-MS in the current study provided a powerful tool for the fast and sensitive analysis of three NSAIDs in human plasma and environmental water.

Boronate affinity solid-phase extraction based on functionalized magnesia–zirconia composite for enrichment of nucleosides in human urine

A novel boronic acid functionalized magnesia–zirconia (ZM) based material was facile synthesized by Lewis acid–base chemisorption. The elemental analysis, inductively coupled plasma atomic emission spectrometer (ICP-AES) and Fourier transform infrared spectrometer (FT-IR) have proven the successful attachment of 3-aminophenylboronic acid derivative onto ZM surface. In the present work, the affinity of the resulting material towards cis-diols binding was evaluated by using it as the sorbent for solid-phase extraction of 4 nucleosides (namely cytidine, uridine, guanine and adenosine). The results show that such boronic acid modified magnesia–zirconia composite microparticles were excellent for capturing nucleosides in the system with a wide range of pH and high salt concentration, which could be effectively released using TFA–ACN–H2O (5 : 50 : 45, v/v/v) solution as elution. The 4 nucleosides spiked to untreated urine sample (i.e., no diluting or pH adjustment) were prominently enriched with recoveries in the range of 86–109% and LOD values in the range of 0.003–0.010 μg mL−1. The constructed calibration curves range from 0.05 to 2.0 μg mL−1 showing good linearity correlation coefficient (R ≥ 0.9961) and precision (RSD < 9%). The proposed material would allow for an alternative extraction strategy for identification and quantitative analysis of cis-diols structure compounds in biological samples.

Rapid determination of polycyclic aromatic hydrocarbons in environmental water based on magnetite nanoparticles/polypyrrole magnetic solid-phase extraction

Polypyrrole (PPy)-functionalized Fe3O4 magnetic nanoparticles (Fe3O4–PPy) were prepared and applied as magnetic solid-phase extraction (MSPE) sorbents for the extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. To achieve the optimal extraction performance, several parameters were investigated, including the amounts of sorbent, volume of desorption solvent, extraction and desorption time, inorganic salt and organic solvent content of the sample matrix. Coupled with gas chromatography/mass spectrometry (GC/MS) analysis, a rapid, sensitive and cost-effective method for the analysis of PAHs in aqueous samples was established. The low detection limits (LODs) for the target PAHs in the proposed method were in the range of 0.38 to 5.01 ng L−1, which are much lower than those LODs reported in previous methods. Good linearity of the detection method was obtained with correlation coefficients (R) between 0.9904 and 0.9992. Satisfactory reproducibility was also achieved with relative standard deviations (RSDs) less than 13.3% by an intra- and inter-day precision evaluation. The recoveries of the 10 PAHs in several environmental water samples ranged from 72.4% to 115.7% with the RSDs being less than 9.7%.

Nickel Oxide Nanoparticle-Deposited Silica Composite Solid-Phase Extraction for Benzimidazole Residue Analysis in Milk and Eggs by Liquid Chromatography–Mass Spectrometry

A novel nickel oxide nanoparticle-deposited silica (SiO2@NiO) composite was prepared via liquid-phase deposition (LPD) and then employed as a solid-phase extraction (SPE) sorbent. When the SPE was coupled with liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) analysis, an analytical platform for the sensitive determination of benzimidazole residues in egg and milk was established. The limits of detection of nine benzimidazoles were in the range of 0.8-2.2 ng/mL in milk and 0.3-2.1 ng/g in eggs, respectively, which was 5-10 times superior to the methods with other adsorbents for SPE. The recoveries of nine benzimidazoles spiked in milk and egg ranged from 70.8 to 118.7%, with relative standard deviations (RSDs) being less than 18.9%. This work presented the excellent extraction performance of NiO on benzimidazoles for the first time, and the applicability of the LPD technique used as sorbents for trace analysis in complex matrices was also demonstrated.

[Preparation of magnesia-zirconia based mimetic biomembrane stationary phase and its applications in evaluating drug-membrane interactions].

A novel mimetic biomembrane chromatographic stationary phase of magnesia-zirconia composite matrix was prepared based on the Lewis acid-base interaction between the phosphonate group of phosphatidylcholine residue and the Lewis acid sites of magnesia-zirconia composite. The infrared absorption spectrum and X-ray photoelectron spectrum of the stationary phase illustrated that the magnesia-zirconia composite was successfully modified with phosphatidylcholine. The interactions between the membrane and the drugs were evaluated. It is observed that the log Kmbm values have good relationships with the log Papp, and the linear slope is 1.049, which is near unity. Moreover, on the basis of the thermodynamics derivation, the difference in standard free energies (delta (delta G0)) is introduced to describe the drug-membrane interaction. The results show that the log Kmbm, and delta (delta G0) value provide key information on the transport properties of the drugs. The establishment of this chromatographic model may be a new way for the evaluation of the drug-membrane interactions.

An extraction technique for analytical sample preparation in aqueous solution based on controlling dispersion of ionic surfactant assemblies in isotachophoretic migration

An extraction technique for analytical sample preparation in aqueous solution has been developed based on controlling dispersion of ionic surfactant assemblies. An extraction technique was realized based on controlling dispersion of the ionic surfactant assemblies in their isotachophoretic migration during the extraction by arranging the solutions of leading electrolyte, ionic surfactant and terminating electrolyte in order and applying voltage. Potential of the technique for analytical sample preparation in aqueous solution has been demonstrated by extracting a model sample of four alkylphenones, which were analyzed by HPLC after the extraction. The extraction showed concentration effects on all the four alkylphenones of butyrophenone, valerophenone, hexanophenone and heptanophenone in the model sample. The enrichment factors were 5.29, 7.70, 7.25 and 7.49 for the four alkylphenones of butyrophenone, valerophenone, hexanophenone and heptanophenone, respectively. Linear relationship was obtained with all the four alkylphenones between their chromatographic peak areas before and after the extraction in the range of concentration from 0.05 ppm to 1.5 ppm. The RSD of the chromatographic peak areas in triplicate extractions was 7.97%, 3.75%, 2.91% and 4.45% for butyrophenone, valerophenone, hexanophenone and heptanophenone, respectively. Advantages of the extraction technique developed include ease of operation, low reagent cost, no consumption of organic solvents and no requirement for additional phase separation.