[Advances in synthesis methods and applications of microporous organic networks for sample preparation].

Sample pretreatment is an essential step in chromatographic analysis. Solid phase extraction (SPE) is a widely used sample pretreatment method. In SPE, the quality of the adsorbent directly affects the adsorption and enrichment efficiency of the target compounds as well as the sensitivity and selectivity of the pretreatment and subsequent analysis. Therefore, the selection and development of adsorbents has become a research hotspot. Microporous organic networks (MONs) are a novel type of covalent organic materials that are synthesized by the Sonogashira reaction of aromatic alkynes and aromatic halides. These networks have the advantages of modifiable structures, large specific surface areas, high porosity, and simple synthesis methods. This paper reviews the synthesis and functional modification methods of MONs, with an emphasis on their applications in sample pretreatment. Future development trends are also prospected. In terms of synthesis, the preparation methods for MON-based materials have progressed from reflux and solvothermal synthesis to room-temperature synthesis, the conditions of which tend to be milder and more efficient. In terms of functional modification, the introduction of macromolecules and active groups (including amino, hydroxyl, and carboxylic groups) can increase the selectivity and active sites of MON-based materials. The combination of MONs with Fe3O4, SiO2, and metal organic frameworks yields core-shell-structured MONs. Furtherly, they can be calcined and etched to form porous carbon structures or hollow multilayer materials. Functionalized MONs and their composite materials have multiple interaction mechanisms (e. g., hydrogen bonding, hydrophobic, electrostatic, and π-π interactions) with various target compounds, thereby realizing their efficient extraction. MONs can be used as adsorbent materials in SPE, Solid phase microextraction, dispersed solid phase extraction, magnetic solid phase extraction, and other pretreatment methods. When combined with chromatography and chromatography-mass spectrometry, MONs achieve good adsorption effects and high sensitivity, demonstrating the application potential of these materials in sample pretreatment.

System to screen and purify active ingredients from herbal medicines using hydrogel-modified human umbilical vein endothelial cell membrane chromatography coupled with semi-preparative high-performance liquid chromatography-offline-high-performance liquid chromatography-mass spectrometry.

Analytical screening and validation systems based on a combination of cell membrane chromatography and two-dimensional chromatography-tandem mass spectrometry are incapable of providing prepared samples containing the active ingredients found in traditional Chinese medicine; therefore, these samples cannot be directly used in subsequent studies. In this study, a semi-preparative cell membrane chromatography column was developed using a hydrogel-modified carrier and human umbilical vein endothelial cells to optimize prepared conditions, such as hydrogel polymerization, cell fragmentation, and cell membrane volume. This increased the binding ratio of membrane protein and carrier to 15.79 mg/g. The column was systematically evaluated using multitarget tyrosine kinase inhibitors that displayed good specificity and reproducibility. Subsequently, using the column coupled with a semi-preparative high-performance liquid chromatography-offline-high-performance liquid chromatography-mass spectrometry system, 15 active ingredients were screened and purified from Indigo naturalis, and five main components were identified: l-lysine, oxyresveratrol, tryptanthrin, isorhamnetin, and indirubin. Furthermore, the pharmacological effects of the ingredients were confirmed using cell proliferation and apoptosis assays. Results revealed potent proliferation-inhibiting and apoptosis-promoting abilities on human chronic myelogenous leukemic cells and human promyelocytic leukemic cells (p < 0.001). Overall, the system presented screening and purification functions that could be used to prepare I. naturalis samples acting on the epidermal growth factor receptor and vascular endothelial cell growth factor.

An agaric-like covalent organic framework composite for efficient extraction of trace cytokinins in plant samples.

Covalent organic framework composites have received great interest and regarded as new-generation porous materials in application of sample preparation. In this work, an agaric-like graphene oxide @ covalent organic framework (AGO@COF) composite was first synthesized and used as an ideal adsorbent for enrichment of trace cytokinins (CKs) due to its large specific surface area, rich in micro-mesopore and organic functional groups. The contact areas between AGO@COF composite and CKs were greatly increased due to the special agaric-like morphology, which would further improve the extraction efficiency. Hence, a rapid, simple and efficient AGO@COF-based dispersive solid-phase extraction method for detecting four CKs (N6-(delta 2-isopentenyl)-adenine, kinetin, DL-dihydrozeatin and 6-benzylaminopurine) was successfully established. The proposed method had low limits of detection (0.1-2.0 pg mL-1), good reproducibility (RSDs≤3.9%, n=5) and high recoveries (84.4-107.7%). With this method, N6-(delta 2-isopentenyl)-adenine and 6-benzylaminopurine in plants were successfully detected and quantified. Results showed that the developed AGO@COF composite possessed superior extraction performance and potential application in enrichment of trace targets from complex plant samples.

[Novel adsorption material for solid phase extraction in sample pretreatment of plant hormones].

Plant hormones (PHs) are of significance in plant growth, as they regulate the various processes related to plant growth, development, and resistance. Sensitive and precise quantitative analysis of PHs is a bottleneck in plant science research. Currently, liquid chromatography-tandem mass spectrometry is used for the accurate and efficient detection of PHs. Sample pretreatment is an indispensable step in the chromatography-mass spectrometry analysis of PHs because it directly affects the sensitivity and accuracy of subsequent detection methods. Among various pretreatment methods for PHs, solid phase extraction (SPE) is the most widely used. Various new types of SPE, such as dispersive SPE, magnetic SPE, and solid phase microextraction, have been developed by modifying the extraction cartridge. The choice of adsorption material is the key factor in the abovementioned SPE methods, which has a decisive effect on the extraction, purification, and enrichment effects of the target substance in the sample pretreatment process. Carbon-based materials, including carbon nanotubes, graphene, carbon and nitrogen compounds, as well as organic frameworks, including metal organic frameworks and covalent organic materials, are suitable adsorption materials because of their designable structure, large specific surface area, and good stability. Molecularly imprinted polymers and supramolecular compounds show specific molecular recognition based on host-guest interactions, which can significantly improve the selectivity of sample pretreatment methods. In this paper, SPE-related technology and the abovementioned types of functionalized adsorption materials in the pretreatment of PHs prevalent in the past five years have been reviewed. The related development trends are also summarized.

Antileukemic effects of indigo naturalis constituents by "target constituent knock-out" coupled with semipreparative liquid chromatography and quadrupole time-of-flight mass spectrometry.

A novel approach is presented to identify constituents with antileukemic properties in extracts of Indigo naturalis (Qingdai in Chinese). Target compounds (A+ , BC+ , and ABC+ ) that knocked out specific constituents displayed antileukemic effects in a total extract of I. naturalis and negative constituents (A- , BC- , and ABC- ) that knocked out target compounds were separated, identified and knocked out by semipreparative liquid chromatography (semipreparative HPLC) and quadrupole time-of-flight mass spectrometer. Quantitative methods were used to evaluate the content of each knocked-out constituent in the total extract (D). Subsequently, interactions between the antileukemic effects of knocked-out constituents and D were screened and evaluated at the cellular level. Negative constituents including A- (65.47% ± 1.20%), BC- (54.61% ± 2.43%) and ABC- (67.49% ± 3.28%) displayed a greater inhibitory effect than D (47.16% ± 0.072%), which was not knocked out after 24 h of incubation, whereas the target compounds had not superior. Target compounds may have caused an antagonistic effect on the corresponding negative constituents. After 48 h, inhibition of proliferation by D (75.48% ± 3.78%) increased compared with that by negative constituents, whereas the antagonistic effect of target components on negative constituents was diminished. This result may reflect competitive antagonism. Comparing the reactions after 24 and 48 h, the inhibitory ratio of ABC- (79.29% ± 1.22%) in these knocked-out constituents and D was always the highest. With different concentrations tested after 48 h, ABC- significantly increased the rate of apoptosis on K562 cells (P < 0.01), indicating that in addition to indirubin, tryptanthrin and isorhamnetin, other antileukemic constituents may be present. Our study presents an approach that is a truer reflection of the antileukemic effects of knocked-out constituents in I. naturalis supported by reference to pharmacodynamic actions and the quality of I. naturalis. The approach may be useful for the analysis of other herbal extracts found in traditional Chinese medicine.

One-pot room-temperature synthesis of covalent organic framework-coated superhydrophobic sponges for highly efficient oil-water separation.

Frequent oil-spill accidents not only cause serious and long-term damage to marine ecosystems, but also lead to a huge loss of valuable natural resources. To lighten the environmental pollution of oil spills as quickly as possible, an efficient and environment-friendly approach for oil-water separation is highly desirable. Herein, a facile one-pot room-temperature approach was developed for large-scale fabrication of covalent organic framework-coated superhydrophobic sponges (sponges@COFs). The as-prepared sponges@COFs possessed many superior properties, including superhydrophobicity with the water contact angle of approximately 154.3°, large specific surface area (153.059 m2/g), high porosity of the network structures, as well as good mechanical and chemical stability. Taking the aformentioned advantages together, the superhydrophobic sponges showed ultra-high adsorption capacity for oil and various organic solvents. In comparision with its own weight, the adsorption amount of the sponges@COFs for silicone oil was up to 150 times and for toluene was 125 times, respectively. Furthermore, the superhydrophobic sponges also showed fast and highly efficient oil-water separation, outstanding flame retardancy and recyclability. In addition, the sponges@COFs were successfully applied to the high-efficiency removal of oil suspension from industrial waste water, firmly confirming their application prospect in industrial wastewater treatment.

Self-assembly synthes is of trypsin-immobilized monolithic microreactor for fast and efficient proteolysis.

Fast and highly efficient digestion of proteins is essential for high-throughput proteomic analysis. Herein, a facile approach was developed for self-assembly preparation of trypsin-immobilized capillary monolithic column and its application as an immobilized enzyme microreactor (IMER) for fast and highly efficient proteolysis was described. The performance of the trypsin-immobilized monolithic enzyme microreactor was evaluated by in-situ digestion of model proteins. The results showed that the trypsin-immobilized monolithic enzyme microreactor had much higher tryptic digestion efficiency than the free trypsin in solution, where the coverage of peptide sequences by mass spectrometry (MS)-based analysis could bear comparison with the free one, while the digestion time was dramatically shortened from 12 h to 16 s. Furthermore, the trypsin-immobilized monolithic enzyme microreactor also exhibited good practicability to complex human serum sample, in which the total of 45 peptides from human serum albumin (HSA) matched with sequence coverage of 75% were precisely identified. The successful application demonstrated the promising potential of the trypsin-immobilized capillary monolithic column as the IMER in high-throughput proteomic analysis.

A fish scale-like magnetic nanomaterial as a highly efficient sorbent for monitoring the changes in auxin levels under cadmium stress.

Sorbents with high surface utilization and good dispersibility are of great importance for the extraction performance of magnetic solid-phase extraction (MSPE). In this study, a fish scale-like magnetic nanomaterial (Co@Co3O4/OCN) was synthesized, which can be used as a highly efficient MSPE sorbent due to its strong magnetism, special morphology, doping of N element, numerous micro-mesopore cavities and organic functional groups (hydroxyl and carboxyl). Furthermore, a Co@Co3O4/OCN-based MSPE method for monitoring the changes in the levels of three auxins (indole-3-acetic acid, indole-3-propionic acid and 3-indole butyric acid) was successfully established. Wide linear ranges (1.0-1000.0 pg mL-1) with good correlation coefficients (R > 0.9992), low limits of detection (LODs, 0.2-4.0 pg mL-1) and satisfactory repeatability (RSD ≤5.9%, n = 3) were obtained. Using the developed method, various growth parts and different growth periods of plants under Cd stress were monitored. The results showed that auxins in various parts of plants showed differential response under Cd stress, and there was a threshold for the changes in auxin levels against Cd stress. This indicates that the developed fish scale-like Co@Co3O4/OCN nanomaterial has a good application prospect for enriching small molecular targets containing hydroxyl and carboxyl groups.

Metal-organic framework-derived nitrogen-doped carbon nanotube cages as efficient adsorbents for solid-phase microextraction of polychlorinated biphenyls.

An efficient and stable adsorbent is of critical importance for solid-phase microextraction (SPME). In this study, we prepared metal-organic framework-derived nitrogen (N)-doped carbon (C) nanotube cages (N-CNTCs) with unique N-doped active sites and C-rich nanotubes to coat SPME adsorbents. This new material was obtained via a simple thermal treatment with ZIF-67, and exhibited high porosity and excellent chemical and thermal stability. Compared with commercial fibers and traditional C nanotubes-coated fiber (15 nm), N-CNTC-coated fiber exhibited better extraction properties, mainly due to its π-π interactions, abundant active sites, and hollow cage structure, which is composed of interconnected crystalline N-doped C nanotubes. N-CNTC-coated fiber exhibited better extraction performance and shorter extraction equilibrium time than the solid N-doped C-coated fiber due to its hollow cage structure. The N-CNTC-coated fiber was then used to identify polychlorinated biphenyls (PCBs) with wide linear range (0.3-1000.0 ng L-1), low limits of detection (0.10-0.22 ng L-1), good repeatability (intra-day, 2.6-3.8%; inter-day, 3.3-4.8%), and good reproducibility (<8.6%). We then successfully applied the N-CNTC-coated fiber to detect PCBs in river water samples from six cities in Fujian Province and obtained satisfactory recovery levels. Thus, the novel N-CNTCs coating proposed in this study is a promising candidate for SPME coating.

Preparation and application of molecularly imprinted polymer solid-phase microextraction fiber for the selective analysis of auxins in tobacco.

As signal molecules, auxins play an important role in mediating plant growth. Due to serious interfering substances in plants, it is difficult to accurately detect auxins with traditional solid-phase extraction methods. To improve the selectivity of sample pretreatment, a novel molecularly imprinted polymer -coated solid-phase microextraction fiber, which could be coupled directly to high-performance liquid chromatography, was prepared with indole acetic acid as template molecule for the selective extraction of auxins. The factors influencing the polymer formation, such as polymerization solvent, cross-linker, and polymerization time, were investigated in detail to enhance the performance of indole acetic acid-molecularly imprinted polymer coating. The morphological and chemical stability of this molecularly imprinted polymer-coated fiber was characterized by scanning electron microscopy, infrared spectrometry, and thermal analysis. The extraction capacity of the molecularly imprinted polymer-coated solid-phase microextraction fiber was evaluated for the selective extraction of indole acetic acid and indole-3-pyruvic acid followed by high-performance liquid chromatography analysis. The linear range for indole acetic acid and indole-3-pyruvic acid was 1-100 µg/L and their detection limit was 0.5 µg/L. The method was applied to the simultaneous determination of two auxins in two kinds of tobacco (Nicotiana tabacum L and Nicotiana rustica L) samples, with recoveries range from 82.1 to 120.6%.

Electrospun UiO-66/polyacrylonitrile nanofibers as efficient sorbent for pipette tip solid phase extraction of phytohormones in vegetable samples.

In this work, metal-organic framework particles incorporated fibers (UiO-66/PAN nanofibers) were used as adsorbent in pipette tip solid phase extraction (PT-SPE) for the first time. The UiO-66/PAN nanofibers were fabricated by a facile electrospinning method and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and nitrogen adsorption-desorption experiments. The UiO-66/PAN nanofibers were applied to assemble a novel PT-SPE cartridge for determination of four phytohormones followed by high performance liquid chromatography (HPLC). Several experimental parameters such as kinds of UiO-66/PAN nanofibers, the amount of UiO-66/PAN nanofibers, the effect of solution pH, ionic strength and desorption conditions were intensively investigated. Under the optimal conditions, the linear ranges of the phytohormones were in the range of 0.06-60 ng/mL with correlation coefficients above 0.992. The limits of detection were between 0.01 ng/mL to 0.02 ng/mL. The interday and intraday precision (RSD) for three replicate extractions of the four phytohormones (15 ng/mL for each) was in the range of 1.5-5.6%. The established method was successfully applied for the determination of phytohormones in watermelon and mung bean sprouts samples. The results showed that the electrostatic interaction between the positively charged UiO-66 and anionic forms of phytohormones played an important role in the extraction of the phytohormones.

Prenatal levonorgestrel exposure induces autism-like behavior in offspring through ERß suppression in the amygdala.

BACKGROUND: Autism spectrum disorder (ASD) is characterized by impairments in social communication and restricted or repetitive behaviors or interests. ASD is now diagnosed in more than one out of 100 children and is biased towards males by a ratio of at least 4:1. Many possible explanations and potential causative factors have been reported, such as genetics, sex, and environmental factors, although the detailed mechanisms of ASD remain unclear. METHODS: The dams were exposed through oral contraceptives to either vehicle control (VEH) alone, levonorgestrel (LNG) alone, ethinyl estradiol (EE) alone, or a combination of LNG/EE for 21 days during their pregnancy. The subsequent 10-week-old offspring were used for autism-like behavior testing, and the limbic tissues were isolated for analysis. In another experimental group, 8-week-old male offspring were treated by infusion of ERß overexpression/knockdown lentivirus in the amygdala, and the offspring were analyzed after 2 weeks. RESULTS: We show that prenatal exposure of either LNG alone or a LNG/EE combination, but not EE alone, results in suppression of ERß (estrogen receptor ß) and its target genes in the amygdala with autism-like behavior in male offspring, while there is a much smaller effect on female offspring. However, we find that there is no effect on the hippocampus and hypothalamus. Further investigation shows that ERß suppression is due to LNG-mediated altered methylation on the ERß promoter and results in tissue damage with oxidative stress and the dysfunction of mitochondria and fatty acid metabolism, which subsequently triggers autism-like behavior. Overexpression of ERß in the amygdala completely restores LNG-induced ERß suppression and autism-like behaviors in offspring, while ERß knockdown mimics this effect, indicating that ERß expression in the amygdala plays an important role in autism-like behavior development. CONCLUSIONS: We conclude that prenatal levonorgestrel exposure induces autism-like behavior in offspring through ERß suppression in the amygdala. To our knowledge, this is the first time the potential effect of oral contraceptives on the contribution of autism-like behavior in offspring has been discovered.

Magnetic porous ß-cyclodextrin polymer for magnetic solid-phase extraction of microcystins from environmental water samples.

Microcystins (MCs) are cyclic heptapeptide toxins and tumor promoters produced by cyanobacteria, which threaten the health of humans. In this study, magnetic porous ß-cyclodextrin polymer (Fe3O4@SiO2@P-CDP) was synthesized and characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectrometry, X-ray diffraction, nitrogen adsorption porosimetry and vibrating sample magnetometer. The synthesized Fe3O4@SiO2@P-CDP particles were then used for magnetic solid-phase extraction (MSPE) of MCs from environmental water samples, and exhibited excellent extraction performance, especially for MC-RR. Coupled with high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), a simple, efficient and sensitive method for determination of trace levels of MCs was established. After the optimization of conditions, wide linear ranges (2.0-1000pgmL-1), good linearity (r2≥0.9996) and acceptable repeatability (RSD≤9.4%, n=5) were obtained. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) for three MCs (MC-LR, MC-RR and MC-YR) were in the range of 1.0-2.0pgmL-1 and 2.0-5.0pgmL-1, respectively. Typical water samples were analyzed by the developed method, and trace levels of MC-LR and MC-RR were detected. The results demonstrate that the developed method has great potential for the determination of MCs in complicated matrix.

ERß expression in the endothelium ameliorates ischemia/reperfusion-mediated oxidative burst and vascular injury.

Estrogen and estrogen receptors (ERs) have been reported to play protective roles in ischemia/reperfusion (I/R)-mediated injury, but the detailed mechanism remains to be fully understood. Nitric oxide (NO) and reactive oxygen species (ROS) also play important roles in the I/R process; however, due to the lack of sensitive and reproducible in vivo monitoring systems, we still do not have direct evidence for the effect of NO and ROS in vivo. In this study, we have established reliable in vivo monitoring systems to measure the variations in circulating ROS and NO during the I/R. We found that during the first few minutes of post-ischemia reperfusion, an oxidative burst occurred concurrent with a rapid loss of NO. Expression of ERß in the endothelium reduced these effects that accompanied an attenuation in myocardial infarction and vascular damage. Further investigation showed that Tie2-driven lentivirus delivery of ERß to the vascular wall in rats increased the expression of its target genes in the endothelium, including ERRα, SOD2 and eNOS. These changes modulate ROS generation, DNA damage, and mitochondrial function in rat endothelial cells. We also found that ERß expression in the endothelium reduced ROS generation and restored mitochondrial function in cardiomyocytes; this may be due to ERß-mediated NO formation and its high diffusibility to cardiomyocytes. We conclude that ERß expression in the endothelium ameliorates ischemia/reperfusion-mediated oxidative burst and vascular injury.

Ferrite nanospheres-based magnetic solid-phase extraction for determination of domoic acid in seawater samples using high-performance liquid chromatography with tandem mass spectrometry.

A simple, rapid and sensitive method for determination of trace levels of domoic acid (DA) in seawater was developed, based on a magnetic solid-phase extraction (MSPE) followed by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Five kinds of ferrite magnetic nanospheres (MFe2O4; M=Fe, Co, Ni, Cu and Zn) were prepared and first used as sorbents for MSPE of DA and removal of salt interference. Under the same extraction and elution conditions, CuFe2O4 magnetic nanospheres provided the best pretreatment performance, which were then characterized in detail. After further optimization of conditions, the developed method showed good linearity (r(2)=0.9991) with the range of 5-1000 pg mL(-1), low limit of detection (2.5 pg mL(-1); S/N=3:1), low limit of quantification (5.0 pg mL(-1); S/N=10:1), and good recoveries (86.0-98.1%) with acceptable repeatability (RSD ≤ 6.5%; n=3) in seawater samples. The results demonstrated that the ferrite magnetic nanospheres are promising sorbents for efficient extraction of highly polar analytes from high ionic strength solutions.

On-line concentration and pressurized capillary electrochromatography analysis of five ß-agonists in human urine using a methacrylate monolithic column.

A pressurized capillary electrochromatography (pCEC) method combined with an online concentration was developed for the separation and determination of five ß2 -blockers (terbutaline, salbutamol, formoterol, procaterol and salmeterol) in human urine. A stearyl methacrylate-based monolithic column was prepared as the separation column. The various separation parameters including acetontrile concentration, applied voltage, pH and concentration of the running buffer were investigated. On-line concentration methods in combination of the chromatographic zone-sharpening effect and field-enhanced sample-stacking effect were utilized to improve detection sensitivity. The on-line concentration parameters including injection voltage, injection time, as well as sample matrix were systematically studied. Compared with the conventional sample injection, the on-line concentration technique appeared to improve the corresponding sensitivities 20∽50-fold. Furthermore, good precision was obtained with relative standard deviations (RSDs) for retention times within 1.09% and for peak areas less than 3.55% (n = 5). The established method was successfully applied to the determination of above-mentioned ß2 -agonists in urine samples. The recoveries of spiked urine samples were between 85.0 and 113.3% with RSDs less than 5.39%.

Simultaneous determination of plant hormones in peach based on dispersive liquid-liquid microextraction coupled with liquid chromatography-ion trap mass spectrometry.

Fruit development is influenced greatly by endogenous hormones including salicylic acid (SA) and abscisic acid (ABA). Mass spectrometry with high sensitivity has become a routine technology to analyze hormones. However, pretreatment of plant samples remains a difficult problem. Thus, dispersive liquid-liquid microextraction (DLLME) was used to concentrate trace plant hormones before liquid chromatography-ion trap mass spectrometry (LC-ITMS) analysis. Standard curves were linear within the ranges of 0.5-50, 0.2-20ng/mL for SA and ABA, respectively. The correlation coefficients were greater than 0.9995 with recoveries above 87.5%. The limits of detection were 0.2ng/mL for SA and 0.1ng/mL for ABA in spiked water solution, respectively (injection 20µL). The successful analysis of SA and ABA in fruit samples indicated our DLLME-LC-ITMS approach was efficient, allowing reliable quantification of both two compounds from very small amounts of plant material. Moreover, this research revealed the relationship between SA and ABA content and development of peach fruit at different growth stages.

Novel multifunctional acceptor phase additive of water-miscible ionic liquid in hollow-fiber protected liquid phase microextraction.

In this paper, water-miscible ionic liquid (IL) such as 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) is introduced for the first time as a novel multifunctional acceptor phase additive in hollow-fiber protected liquid phase microextraction (HF-LPME). For investigating the performances of [BMIM]Cl, it was respectively mixed with NaOH, HCl and deionized water. And their extraction performance was preliminary evaluated with alkaline compounds (clenbuterol, metoprolol, carteolol and propranolol), acidic compounds (diethylstilbestrol, hexestrol, phenol and bisphenol A) and neutral compounds (acenaphthylene, fluorene and fluoranthene). Furthermore, a complete extraction and determination method using IL-three phase HF-LPME and liquid chromatography was established for polycyclic aromatic hydrocarbons (PAHs) in river water. The extraction conditions, such as concentration of IL, extraction temperature, extraction time, stirring speed, ionic strength and the addition of methanol were studied in detail. Under the optimum conditions, the linear ranges of acenaphthylene, fluorene and fluoranthene were 1-100, 1-200 and 1-200 ng mL(-1), respectively. Limit of detections (LODs) were lower than 0.25 ng mL(-1). The recoveries of PAHs in three kinds of spiked real water are between 90.97 and 109.7% and the precisions are in the range of 2.53-7.01%. Since water-miscible ionic liquids had various forms, similar extraction capabilities to organic solvents and could be conveniently adjusted by acid, alkaline and buffer, this proposed method should have great potentiality in sample preparation of HF-LPME.

pCEC coupling with ESI-MS for the analysis of beta(2)-agonists and narcotics using a poly-(1-hexadecene-co-TMPTMA) monolithic column.

A pressure-assisted CEC with ESI-MS based on poly(1-hexadecene-co-trimethylolpropane trimethacrylate) monolithic column for rapid analysis of two beta(2)-agonists and three narcotics was established in this article. After the organic polymer-based monolithic column was prepared by an in-situ polymerization procedure, a systematic investigation of the pressure-assisted CEC separation and ESI-MS detection parameters was performed. Baseline separation of the studied analytes could be obtained using the solution containing 75% ACN v/v and 20 mmol/L ammonium acetate with pH 8.0 as running buffer, when applying separation voltage of 20 kV and assisted pressure of 5 bar. Under the optimized conditions, two beta(2)-agonists and three narcotics could be completely resolved and accurately determined within 15 min. Finally, the proposed method was successfully used for real urine samples detection.

A new method for the analysis of beta(2)-agonists in human urine by pressure-assisted capillary electrochromatography coupled with electrospray ionization-mass spectrometry using a silica-based monolithic column.

A new pressure-assisted capillary electrochromatography coupled with electrospray ionization-mass spectrometry method using a silica-based monolithic column as separation media was developed for the analysis of beta(2)-agonists in human urine. Experimental conditions including the mobile phase, separation voltage, assisted pressure, and sheath liquid were optimized for the analysis: mobile phase composed of 82% (v/v) ACN and 18% (v/v) 20mmol/L ammonium acetate (pH 6.0); separation voltage 25kV; assisted pressure 2 bar; and the sheath liquid consisting of 7.5mmol/L acetic acid in isopropanol/water 50/50% (v/v) that was delivered at a flow rate of 3.0microL/min. Six beta(2)-agonists were separated within 12.5min with LODs (defined as S/N=3) in the range of 0.25-2.0ng/mL. The absolute LODs of the developed method for analyzing six beta(2)-agonists ranged from 5.75 to 46.0fg. Method repeatability of run-to-run and column-to-column was satisfactory. The recovery obtained from the analysis of spiked urine samples was between 88.2% and 106% with RSDs lower than 6.68%. The method was successfully applied to the analysis of real urine sample from volunteers.