High-speed Separation Research Articles

Electrophoresis-Correlative Data-Independent Acquisition (Eco-DIA) Improves the Sensitivity of Mass Spectrometry for Limited Proteome Amounts.

Capillary zone electrophoresis (CE) combines high separation power, scalability, and speed to limited proteome analyses by mass spectrometry (MS). However, compressed separation in CE challenges the duty cycle of tandem MS, even during data-independent acquisition (DIA). To help remedy this limitation, we introduce the concept of electrophoresis-correlative (Eco) data acquisition for CE-MS. We recognize CE electrospray ionization (ESI) to sort peptide ions into reproducible mass-to-charge (m/z) vs migration time (MT) trends in the solution phase, before subsequent ionization and m/z analysis. We proposed that such a correlation can be leveraged to improve the economy of data acquisition. We test this hypothesis using DIA frames that are tailored to the observed m/z-MT trends. The resulting Eco-DIA method substantially improves the bandwidth utilization of tandem MS during CE-MS. In proof-of-principle studies, Eco-DIA identified and quantified ∼38% more proteins from 1 ng of the HeLa proteome digest compared to the classical DIA, without the assistance of a project-specific tandem MS spectral library. Eco-DIA was able to quantify ∼51% more proteins with <10% coefficient of variation vs the control DIA approach. Based on label-free quantification, the proteins that were exclusively measured by Eco-MS occupied the lower dynamic range of the detected proteome concentration, revealing sensitivity enhancement. In addition to marking the inception of Eco-MS, this work lays the foundation for the development of next-generation data acquisition strategies that leverage electrophoretic ion sorting for high-sensitivity proteomics.

Optimization Design of Oil Groove Shape on the Surface of Friction Plate in High-Speed Wet Clutch Aimed at Minimizing Drag Torque

Abstract The wet clutch, a crucial component of the vehicle transmission system, experiences high-frequency impact and friction between the friction plate and the steel plate under high-speed separation conditions. This leads to a significant increase in drag torque, which is detrimental to the transmission efficiency and reliability of the high-speed wet clutch. This article aims to reduce the high-speed drag torque in a no-load wet clutch by optimizing the oil groove shape on the surface of the friction plate. Initially, a theoretical model of high-speed drag torque for the friction plate with arbitrary oil groove shape is established. Subsequently, a low-drag oil groove shape optimization model is proposed by establishing design parameters, constraint conditions, and an objective function, combined with an experiment design method, approximation modeling, and a global search optimization method. Finally, the stiffness and damping coefficients of the clearance flow field and the drag torque with the optimized oil groove shape are calculated. The simulation results and the proposed optimization method are validated through experiments. The experiment indicates that a friction plate with the optimized oil groove shape can significantly decrease high-speed drag torque, demonstrating strong practical engineering value.

High-temperature ultrafast ChipHPLC-MS

Herein, we present a miniaturized chip-based HPLC approach coupled to electrospray ionization mass spectrometry utilizing temperature to achieve high-speed separations. The approach benefits from the low thermal mass of the microfluidic chip and can form an electrospray from the pre-heated mobile phase. With the help of this technology, isothermal and temperature-programmable operations up to 130°C were pursued to perform reversed-phase separations of pesticides in methanol and ethanol-containing eluents in less than 20 s.Graphical

Comprehensive Chemical Characterization of Qingkailing Capsules by Ultra-High-Performance Liquid Chromatography Combined with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Qingkailing capsules are a classic traditional Chinese medicine prescription with remarkable clinical effects for the treatment of fevers. However, the chemical components of Qingkailing capsules are still unclear. To obtain and characterize the chemical profile of Qingkailing capsules, the present study applied a rapid, accurate, and sensitive method using ultra-high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry (UHPLC-FT-ICR-MS) to perform a comprehensive chemical characterization of Qingkailing capsules. Leveraging the high separation speed and good separation of UHPLC, the accurate mass data (within 5 ppm) and fragment ions, a total of 276 compounds, including 67 flavonoids and their glycosides, 52 organic acids, 75 terpenoids, 23 steroids, 22 phenylpropanoids, and 37 other compounds, were unambiguously or tentatively identified. This comprehensive analysis of the chemical components of Qingkailing capsules contributes to the quality evaluation and provides a scientific and reasonable basis for further study of prototype components and metabolites in vivo and pharmacological research, ultimately facilitating the advancement of Qingkailing capsules for further development and the therapeutic use of Qingkailing capsules in clinical applications.

Multiple-open-tubular column enabling transverse diffusion. Part 3: Simulation of solute dispersion along a real three dimensional-printed column with quadratic channels

Multiple-open-tubular columns enabling transverse diffusion (MOTTD) consist of straight and parallel flow-through channels separated by a mesoporous stationary phase. In Part 1, a stochastic model of band broadening along MOTTD columns accounting for longitudinal diffusion, trans-channel velocity bias, and mass transfer resistance in the stationary phase was derived to demonstrate the intrinsic advantage of MOTTD columns over classical particulate columns. In Part 2, the model was refined for the critical contribution of the channel-to-channel polydispersity and applied to address the best trade-off between analysis speed and performance. In this Part 3, a MOTTD column with a square array of quadratic channels is fabricated by 3D-printing (combining polymer stereolithography with photolithography using photomasks) to deliver unprecedently small apparent channel diameters of 117.6 ± 5.0 μm. The colors in the microscopy photographs of the actual 3D-printed channels are binarized to delimitate the mobile phase volume from the stationary phase volume. The same numerical simulations as those in Part 2 are then performed for two MOTTD columns (external porosity ϵe=31.7%, same apparent channel diameter 117.6 μm): one containing 16 virtual perfect quadratic channels and the other 16 real 3D-printed channels. The reduced velocities (or Peclet numbers) are varied over a wide range from 0.2 to 5000 and the zone retention factors were fixed at k1=1.04, 5, and 25.The results demonstrate that smoothing the edges of the targeted quadratic channels by the 3D-printed technique is advantageous in terms of solute dispersion. It outperforms the negative effect of the channel-to-channel polydispersity which is mitigated by transverse diffusion of the analyte in the stationary phase. For Peclet numbers larger than 50, the HETP of the 3D-printed MOTTD column is found 7%, 15%, and 16% smaller than that of the MOTTD column consisting of a square array of perfect quadratic channels. This confirms the known effect of channel geometry on solute dispersion in microfluidic systems. Flow channels in fabricated MOTTD columns are preferred to be circular so that the distribution of transverse diffusion lengths across the open channels remains as tight as possible. Finally, the general theory of nonuniform columns of Giddings reveals that the polydispersity of the cross-sectional area (RSD 8.4%) along a single 3D-printed channel has no negative impact on solute dispersion in MOTTD columns. Overall, MOTTD columns could become a serious alternative technology to conventional particulate columns. This implies a novel fabrication process that delivers circular channel diameters smaller than 10 μm, cross-sectional area polydispersity no larger than 25%, external porosities in a range from 15% (high speed separations) to 75% (high performance separations), and conventional mesoporous silica as the stationary phase. It adresses new synthesis routes based on either organic fibers or tubular micelle templating agents in suspension with silica gel solutions.

Rapid Purification and Formulation of Radiopharmaceuticals via Thin-Layer Chromatography.

Before formulating radiopharmaceuticals for injection, it is necessary to remove various impurities via purification. Conventional synthesis methods involve relatively large quantities of reagents, requiring high-resolution and high-capacity chromatographic methods (e.g., semi-preparative radio-HPLC) to ensure adequate purity of the radiopharmaceutical. Due to the use of organic solvents during purification, additional processing is needed to reformulate the radiopharmaceutical into an injectable buffer. Recent developments in microscale radiosynthesis have made it possible to synthesize radiopharmaceuticals with vastly reduced reagent masses, minimizing impurities. This enables purification with lower-capacity methods, such as analytical HPLC, with a reduction of purification time and volume (that shortens downstream re-formulation). Still, the need for a bulky and expensive HPLC system undermines many of the advantages of microfluidics. This study demonstrates the feasibility of using radio-TLC for the purification of radiopharmaceuticals. This technique combines high-performance (high-resolution, high-speed separation) with the advantages of a compact and low-cost setup. A further advantage is that no downstream re-formulation step is needed. Production and purification of clinical scale batches of [18F]PBR-06 and [18F]Fallypride are demonstrated with high yield, purity, and specific activity. Automating this radio-TLC method could provide an attractive solution for the purification step in microscale radiochemistry systems.

Rapid separation and identification of 96 main constituents in Huanglian Jiedu decoction via ultra-high performance liquid chromatography-Orbitrap Fusion Tribrid mass spectrometer.

Huanglian Jiedu decoction is a widely used traditional Chinese medicine with a broad spectrum of therapeutic effects, including heat clearing, detoxification, and attenuation of inflammation. However, the composition of Huanglian Jiedu decoction is still unclear due to its complexity and limitations of analytical methods. In this study, we established a fast and reliable analytical method based on ultra-performance LC-Orbitrap Fusion Tribrid mass spectrometer for high-speed separation and structural identification of multiple compounds in Huanglian Jiedu decoction. The analysis was carried out using a Hypersil GOLD C18 column (2.1 × 100 mm, 1.9μm) with gradient elution coupled to a high-definition mass spectrometer system operating in both positive and negative ESI modes. According to the chromatographic retention time, precise molecular weight, fragment ion peaks, and published data, the main chromatographic peaks were attributed to specific molecules whose chemical structures were determined. In total, 96 components were identified, including 34 flavonoids and their glycosides, 23 alkaloids, 18 organic acids, 13 terpenoids, and 8 miscellaneous compounds. This study revealed the detailed chemical composition of Huanglian Jiedu decoction, which is of great importance for quality control and further pharmacological and mechanistic studies.

Superhydrophobic PDMS@GSH wood with Joule heat and photothermal effect for viscous crude oil removal

Recently, the membrane separation materials show promising applications in the fields of crude oil removal because of their low energy consumption and less secondary pollution. However, the membrane separation materials suffer problem of low separation efficiency due to the high viscosity of crude oil. Here, a superhydrophobic material with Joule heat and photothermal effect was prepared by decorating the delignified wood with reduced graphene oxide (GSH) and vinyl terminated polydimethylsiloxane (V-PDMS) through thiol-ene click reaction. The prepared PDMS@GSH wood exhibited stable superhydrophobicity with a water contact angle of 156°. Meanwhile, the GSH layer provided promising electrothermal effect that endowed the PDMS@GSH wood with excellent crude oil/water separation capability under the Joule heat with a surface temperature of 139 °C and separation rate of 1.78 × 105 kg m−3 h−1. Besides, the PDMS@GSH wood displayed a good photothermal effect that assisted with the Joule heat to heat the wood for crude oil removal to save energy. More importantly, the PDMS was crosslinked with GSH on the wood via thiol-ene click reaction, leading to the stable superhydrophobicity and electrical conductivity in strong acid or alkali environment. This material has broad application prospects in crude oil clean-up due to its high separation speed and easy large-scale production.

Abstract 2943: Acoustic cell separation platform for efficient preparation of single cell/nuclei suspension from complex samples for genomics analysis

Abstract Preparing a single cell suspension is a critical step in any solid tissue for genomics analysis as the presence of cellular debris, dead cells and free RNA will cause incorrect cell count, noise in sequencing read and possibly clogging of the microfluidic chip. Single cell preparation not only involves the tissue dissociation process but the “clean-up” step of the dissociation product. Current methods for removing dead cells and debris use magnetic beads and density gradient centrifugation, which are lengthy and costly, and often result in low cell recovery. Here we present a high-speed acoustic cell separation platform—MARS® Sample Preparation system. The system has three independent modules and each has an acoustic cell processing chip (CPC) which creates different moving trajectory of live cells, dead cells, and cellular debris in the acoustic field to achieve high efficiency of single cell separation. MARS® sample preparation provides fast, gentle, and label-free protocol to separate single cells and single nuclei from various types of organs and dissociation processes including manual enzymatic approach and automatic platform. Separated single cells and nuclei demonstrate compatibility with the downstream single cell genomics platform. We here report the separation of live single cells and nuclei from mouse brain tissue dissociation with over 99% removal of myelin and other debris, and 60%-80% recovery of cells and nuclei. Those results were obtained on the MARS® with 0.8mL/min flow rate and three samples in parallel process. Samples before and after MARS® acoustic process were analyzed with both flow cytometry and imaging-based cell counter. The performance of “clean-up” of the acoustic process was compared to conventional Percoll based centrifugation method and showed significant advantage. The results of separating kidney cells/nuclei, lung cells/nuclei, as well as spleen cells also demonstrated high debris removal and cell recovery over several samples processed in multiple batches. MARS® sample preparation platform and its acoustic technology provide a powerful new tool for single cell preparation for expanded application of single cell genomics. Citation Format: Liping Yu. Acoustic cell separation platform for efficient preparation of single cell/nuclei suspension from complex samples for genomics analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2943.

Circulating tumor DNA detection in peripheral blood in postoperative efficacy evaluation and recurrence risk prediction of lung cancer.

This study mainly explores the application in the evaluation of postoperative efficacy and recurrence risk prediction. In this study, 50 lung cancer patients treated with thoracic surgery were selected. Collect the peripheral blood of these patients before the operation, separate the blood sample from the plasma by high-speed centrifugal separation, extract the DNA in the plasma by the magnetic bead method, and then extract the ctDNA. A liquid-phase chip capture system is used to highly concentrate target DNA. We use the IlluminaHiseq platform to sort with high throughput and high depth. As an indicator of ctDNA detection and analysis, the AF value of gene mutation frequency is used for calibration. The sensitivity of CEA detection in peripheral blood of tumor patients (TP) is 30% (15/50), and the sensitivity of ctDNA detection is significantly higher than that of CEA detection. Research results show that the number.

Cu3P nanoparticles decorated hollow tubular carbon nitride as a superior photocatalyst for photodegradation of tetracycline under visible light

• Cu 3 P/HTCN composite was successfully prepared via a simple solvothermal method. • Unique hollow tubular structure greatly improves the light harvesting ability. • Cu 3 P/HTCN composite shows superior photocatalytic activity for degradation of TC. • Cu 3 P effectively inhibits the rapid recombination of photogenerated carrier of HCCN. The construction of stable, efficient and economical visible-light-driven photocatalyst is a practical strategy to deal with antibiotic water contamination. Herein, Cu 3 P nanoparticles/hollow tubular carbon nitride (HTCN) composite was successfully prepared and the photocatalytic activity of Cu 3 P/HTCN was evaluated with tetracycline (TC) as the degradation target antibiotic. Among them, the 6% Cu 3 P/HTCN exhibited optimal photocatalytic degradation rate (96.9% in 40 min), which was 8.3 times higher than that of pure HTCN. The enhancement of photocatalytic performance by Cu 3 P/HTCN is attributed to the introduction of Cu 3 P nanoparticles can not only increase the specific surface area of HTCN to provide abundant reaction sites, but also enhance the capture ability of incident light and promote the high-speed separation and transfer of photogenerated charges. In addition, the electron spin resonance (ESR) technology was used to further confirm that the main active species during the photocatalytic degradation of TC. Furthermore, the possible intermediates in photocatalytic degradation of TC by Cu 3 P/HTCN was the identified with liquid chromatography-mass spectrometry (LC-MS). This work provides an effective way for constructing HTCN-based composite materials for photocatalytic application.

The development of miniSTRs as a method for high-speed direct PCR.

There are situations in which it would be very valuable to have a DNA profile within a short time; for example, in mass disasters or airport security. In previous work, we have promoted reduced size STR amplicons for the analysis of degraded DNA. We also noticed that shorter amplicons are more robust during amplification, making them inhibition resistant, and potentially applicable to high-speed direct PCR. Here, we describe a set of miniSTRs capable of rapid direct PCR amplification. The selected markers are a subset of the Combined DNA Index System (CODIS) loci modified to permit high-speed amplification. Using the proposed protocol, the amplification of eight loci plus amelogenin directly from a saliva sample can be completed in 7 min and 38 s using a two-step PCR with 30 cycles of 98°C for 2s and 62°C for 7s on a Streck Philisa thermocycler. Selection of DNA polymerase, optimization of the two-step PCR cycling conditions, the primer concentrations, and the dilution of saliva is described. This method shows great potential as a quick screening method to obtain a presumptive DNA profile when time is limited, particularly when combined with high-speed separation and detection methods.

Sintered Glass Monoliths as Supports for Affinity Columns

A novel stationary phase for affinity separations is presented. This material is based on sintered borosilicate glass readily available as semi-finished filter plates with defined porosity and surface area. The material shows fast binding kinetics and excellent long-term stability under real application conditions due to lacking macropores and high mechanical rigidity. The glass surface can be easily modified with standard organosilane chemistry to immobilize selective binders or other molecules used for biointeraction. In this paper, the manufacturing of the columns and their respective column holders by 3D printing is shown in detail. The model system protein A/IgG was chosen as an example to examine the properties of such monolithic columns under realistic application conditions. Several specifications, such as (dynamic) IgG capacity, pressure stability, long-term performance, productivity, non-specific binding, and peak shape, are presented. It could be shown that due to the very high separation speed, 250 mg antibody per hour and column can be collected, which surpasses the productivity of most standard columns of the same size. The total IgG capacity of the shown columns is around 4 mg (5.5 mg/mL), which is sufficient for most tasks in research laboratories. The cycle time of an IgG separation can be less than 1 min. Due to the glass material’s excellent pressure resistance, these columns are compatible with standard HPLC systems. This is usually not the case with standard affinity columns, limited to manual use or application in low-pressure systems. The use of a standard HPLC system also improves the ability for automation, which enables the purification of hundreds of cell supernatants in one day. The sharp peak shape of the elution leads to an enrichment effect, which might increase the concentration of IgG by a factor of 3. The final concentration of IgG can be around 7.5 mg/mL without the need for an additional nanofiltration step. The purity of the IgG was &gt; 95% in one step and nearly 99% with a second polishing run.

A PC-based control method for high-speed sorting line integrating data reading, image processing, sequence logic control, communication, and HMI

The vision-based automatic systems for in-line detection, identification, and separation are widely used in the industry, and it is difficult for such systems to achieve a simplified structure, high speed, high efficiency, and integrated coordinated control. Taking the dual-energy x-ray transmission solid waste high-speed sorting line as an example, an automatic control system was proposed, integrating data reading, image processing, sequential logic control, communication, and human–machine interface based on a personal computer with a general operating system. The hardware platform was introduced, and the design principles of operation parameters were investigated. The software was developed in C language with Microsoft Visual Studio 2012. The multi-core multi-thread technology has been utilized in which the optimized process-thread settings (OPTS), first-in first-out (FIFO) stacker, variable sharing between threads, and encoder position synchronization were employed. The whole system was experimentally verified at the line speed of 1 m/s. The results showed that the average scan cycle of sequential logic control was only 15 µs, which could fully ensure the real-time high-speed logic control and accuracy of position synchronization, OPTS improved the stability and disturbance rejection, FIFO stacker and variable sharing between threads was adapted to the realistic buffer materials, the encoder position synchronization avoided the accumulation of measurement errors, and the main operations run in parallel and coordinately and were suitable for the high-speed separation of multiple columns of irregular materials. The presented control system has the advantages of near real-time, high speed, high efficiency, low cost, easy reconstruction, and capability to manage and control integration and has a good practical application value.

Sulfonic acid-modified polyacrylamide magnetic composite with wide pH applicability for efficient removal of cationic dyes

In order to deal with the increasingly serious water pollution caused by dye wastewater, a novel sulfonic acid-modified polyacrylamide magnetic composite (Fe3O4@SiO2/P(AM-AMPS)) was facilely prepared by crosslink reaction. The physicochemical properties and adsorption performances of Fe3O4@SiO2/P(AM-AMPS) were systematically studied by different characterization techniques and a series of batch experiments, respectively. It was found that the adsorption capacities of Fe3O4@SiO2/P(AM-AMPS) towards cationic dyes crystal violet (CV) and methylene blue (MB) were largely enhanced than those of silica-coated Fe3O4 (Fe3O4@SiO2) and maintained at relatively high levels in a wide pH range, due to the three-dimensional network structure and abundant functional groups of modified polyacrylamide. Besides, owing to the introduction of Fe3O4@SiO2, Fe3O4@SiO2/P(AM-AMPS) presented a unique magnetic property that helped it to be rapidly separated from water in a magnetic field. The maximum adsorption capacities of Fe3O4@SiO2/P(AM-AMPS) were 2106.37 mg g−1 for CV removal and 1462.34 mg g−1 for MB removal at 298.15 K, much higher than those of other reported magnetic composites. Furthermore, Fe3O4@SiO2/P(AM-AMPS) was effectively regenerated with HCl solution and the regeneration rates were higher than 97% and 80% for CV and MB removal after five adsorption-desorption cycles, respectively. With its excellent adsorption capacity, wide pH applicability, high separation speed, and satisfactory regeneration ability, Fe3O4@SiO2/P(AM-AMPS) was expected to become a promising adsorbent in the purification of cationic dye wastewater.

Production of Magnetically Controlled Biosorbents Based on Fungi Pleurotus ostreatus

Background. Biogenic magnetic nanoparticles (BMN) have been found in representatives of all three superkingdoms of living organisms: bacteria, archaea and eukaryotes (including fungi). At the same time, it was established that the mechanism of biomineralization of BMN is unique for all living organisms. The search for sorbents of biological origin has become one of promising ways of addressing the problem of environmental pollution by heavy metals. Heavy metals are elements of transport emissions and many factories in various industries. These metals getting into the human body cause significant disruption of metabolism and vital functions of the body. Many macromycetes are known to be natural sorbents for heavy metal ions. Laboratory tests use a method of filtering spent sorbent through a paper filter, which is long enough and inefficient. Therefore, it is important to find a more effective way of removing biosorbent from the solution. Such a cheap and efficient method is high-speed magnetic gradient separation. Objective. The aim of the paper is to obtain a magnetically controlled biosorbent based on a fungus Pleurotus ostreatus , to determine the fraction of the magnetically controlled phase of the fungus biomass when added to the substrate of the magnetic fluid, and to investigate the efficiency of extraction of Fe 3+ ions by the fungus biomass of the fungus Pleurotus ostreatus . Methods . The standard method of cultivation of the fungus Pleurotus ostreatus , the method of high-grade magnetic separation and the method of biosorption of ferric ions were used. Results. The process of biosorption of ferric ions by a Pleurotus ostreatus grown on substrates with the addition of magnetic fluids of different concentrations was carried out. It is shown that the dry biosorbent based on the biomass of the Pleurotus ostreatus has a high sorption capacity with respect to Fe 3+ ions since the efficiency of their extraction for 30 minutes of sorption in the samples grown on the substrate with the addition of magnetite is more than 95%. It is proved that when using biomass of ordinary fungus grown on a magnetic fluid, complete saturation occurs 6 times faster (for 5 minutes), compared to 30 min for biosorbent based on biomass of mushroom grown without magnetic fluid. Conclusions. Addition of magnetite (concentration 0.1 and 1 mg/ml) to the substrate in the cultivation of fungi Pleurotus ostreatus significantly increases the efficiency of the sorbent. When using the fungus biomass of Pleurotus ostreatus without adding magnetite for 5 minutes, the efficiency of extraction of iron ions is 70%, for 30 min – 80%. When used to grow the magnetic fluid at a concentration of 0.1 mg/ml and 1 mg/ml for almost 5 minutes, almost complete removal of heavy metal ions occurs.

A Plug-and-Play High-Pressure ESI Source with an Emitter at Ground Potential and Its Application to High-Temperature Capillary LC-MS.

A new high-pressure ESI source that can be readily used for commercial API mass spectrometers in a plug-and-play manner without any modification on the ion sampling interface is introduced. The emitter can be operated at ground potential, and the positive mode electrospray is generated by applying a negative high potential to the counter electrode. A shielding electrode effectively shields the opposing electric field and improves the ion transmission. This feature facilitates the direct connection of the ESI emitter to the electrically grounded components. The application of the present ion source to the high-temperature (>100 °C) capillary liquid chromatography for high-speed separation of peptide and proteins is demonstrated using a monolithic polymeric column.

Underwater Superoleophobic and Salt-Tolerant Sodium Alginate/N-Succinyl Chitosan Composite Aerogel for Highly Efficient Oil–Water Separation

Materials for oil–water separation under harsh conditions that exhibit high separation efficiency, salt tolerance, and the capability of high-speed separation and reusability are in great demand. I...

Progress in application of functionalized magnetic nanomaterials for sample pretreatment

With the increasing complexity of the sample properties in analytical chemistry and the lower concentrations of the detected substances, it is imperative to develop accurate and efficient sample pretreatment processes before chromatography and mass spectrometry analyses. Magnetic solid-phase extraction (MSPE) can be regarded as an efficient sample pretreatment method due to the simple synthesis, convenient operation, and high extraction efficiency. In recent years, Fe3O4 magnetic nanomaterials have been widely used in separation and analysis due to their advantages such as high separation speed, good dispersion, and biocompatibility. Functionalized Fe3O4 magnetic nanomaterials are expected to show greatly improved physical and chemical stability, with superior adsorption and separation ability. In this paper, the preparation of magnetic nanomaterials functionalized with carbon-based nanomaterials, molecularly imprinted polymers, ionic liquids, boronate affinity ligands, metal organic frameworks, covalent organic frames, quantum dots, and metal oxides and their applications to sample pretreatment in the fields of biological, environmental, and food safety are reviewed. In addition, future research on sample pretreatment processes is prospected.

Efficient separation of V(V) and Cr(VI) in aqua by microemulsion extraction

Separation of V(V) and Cr(VI) in aqua is intensively demanded in consideration of full resource utilization and environmental safety of vanadium extraction industry, which is however a challenge due to their highly similar chemical properties. In this work, chromium transformation is firstly conducted to convert Cr(VI) anions into Cr(III) cations that are differentiable from V(V) anions. Then, the microemulsion system of Aliquat 336/isoamyl alcohol/n-heptane/NaCl is utilized to selectively extract V(V) anions by method of microemulsion extraction and leave Cr(III) cations in the raffinate, leading to the separation of V and Cr. In optimal conditions of microemulsion extraction, the extraction efficiency of V is as high as 98.45% while that of Cr is only 4.44%, confirming the efficient separation of V and Cr in aqua. Extracted V is retrieved back to aqueous solution by stripping V-loaded microemulsion and simultaneously concentrated by 4 times with total recovery of 97.91%; Cr(III) left in the raffinate is environmentally safe and ready for direct precipitation recovery. The achieved separation of V(V) and Cr(VI) is thus not only efficient, but also beneficial to their subsequent recovery. This work has demonstrated a powerful separation method for V(V) and Cr(VI) with high separation capacity, efficiency and speed, which lays the essential foundation for the recovery and comprehensive utilization of V and Cr resources in vanadium metallurgy industry.