Journal of separation science最新文献

Additive manufacturing is transforming how microfluidic devices are prototyped and fabricated. Among various 3D printing methods, stereolithography (SLA) has become a dominant technique for microfluidics due to its high resolution and design flexibility, with widespread use in lab-on-a-chip applications. However, intrinsic limitations of SLA printing, such as challenges related to multi-material integration and microstructure fabrication in enclosed channels, continue to hinder the development of more complex microsystems, especially for analytical separation and tissue engineering applications. In this paper, we present a multiphase flow-assisted in situ 3D printing method to address these challenges, developed based on our previously reported in situ 3D polymerization (IS-3DP) concept. Our method utilizes an aqueous two-phase system (ATPS) to generate sequential printing layers through controlled fluidic confinement and integrates an image-guided alignment system to enable precise projection of printing patterns in microchannels. We demonstrate that viscosity tuning of the ATPS printing and blocking phases enables dynamic control of layer thickness, allowing customized and adaptive design of the 3D structure slicing. The image-guided alignment system employs a homography transformation mechanism to map the projection and printing planes via image feedback, providing real-time mask alignment with microchannel geometries. We characterize the mapping accuracy and projection fidelity and demonstrate the capability of this method by direct in-channel fabrication of complex 3D microstructures such as pyramids, cuboids, bridge-like void structures, as well as multi-material patterns. We envision the multiphase flow-assisted in situ 3D printing to offer a versatile tool for spatially controlled, high-fidelity, and multi-material microfabrication within confined microchannels in novel lab-on-a-chip applications.

In this contribution, an efficient high-performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of four impurities in trihexylphe idyl hydrochloride. The developed HPLC method was based on an octadecylsilane-bonded silica gel column (Agilent TC-C18 250 mm × 4.6 mm, 5 µm) as the stationary phase, and the solvents were sodium hexafluorophosphate 0.05 mol/L and methanol for the gradient elution at a flow rate of 1.0 mL/min, with the injection volume of 20 µL, the ultraviolet (UV) detection at a wavelength of 210 nm, and the column temperature of 30°C. Under the established chromatographic conditions, all four target impurities were completely eluted within 30 min. The proposed method demonstrates good specificity, precision, robustness, and accuracy for the quantification of the four critical impurities in trihexyphenidyl hydrochloride, and was successfully applied for the analysis of trihexyphenidyl hydrochloride in a pharmaceutical preparation.

Seaweeds represent an excellent vegetable protein resource capable of supporting the objectives of the sustainable blue economy. Today, attention toward algae is growing, due to their applications, both in biofuel production and as an alternative source of healthy food and nutraceuticals. The objective of this work was to valorize marine macroalgae coming from the Mediterranean area in order to be able to expand their potential use in the nutraceutical and pharmaceutical industries, maintaining the circularity of financial and biological resources. Micronutrients with higher antioxidant activity were determined in 10 samples, specifically four red algae, four brown algae, and two green algae. In particular, vitamin C was analyzed using a reversed phase (RP)-HPLC system coupled to photodiode array (PDA) detection, following extraction with an acidified aqueous solution. Vitamin E analysis was performed using a normal-phase HPLC system, following extraction with n-hexane and taking advantage of the high selectivity and sensitivity of fluorescence detector. Vitamin B12 was extracted with an acidified solution of methanol and water and analyzed by RP-HPLC system coupled to PDA and MS, the latter operated under selected ion monitoring mode to increase instrumental sensitivity and selectivity. Finally, carotenoids and pigments were extracted with an acetone/methanol solvent mixture and analyzed by RP-HPLC system coupled to PDA and MS to exploit the complementarity between MS and UV spectra for identification purposes. Overall, the validated HPLC methods confirmed the presence of vitamin E in all the samples analyzed, with highest levels obtained in two brown algae, namely, Undaria pinnatifida (1.54 ± 0.08 mg/kg) and Himanthalia elongata (0.93 ± 0.02 mg/kg), whereas vitamins C and B12 were detected only in two macroalgae species, including the widely consumed Porphyra sp., commercially known as Nori. Finally, carotenoids were mainly determined in the largely consumed U. pinnatifida sample, commercially known as Wakame.

A molecularly imprinted polymer (MIP) was successfully synthesized through precipitation polymerization for the purpose of selectively extracting ketoconazole (KCZ) from cosmetic shampoo matrices. The polymerization process employed methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, azobisisobutyronitrile as the initiator, and KCZ as the template within an acetonitrile/acetic acid (9:1, v/v) solvent system. Conditions for synthesis were optimized to enhance efficiency. Material characterization, conducted via Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller analysis, confirmed the successful formation of the polymer. The MIP demonstrated a maximum adsorption capacity of 1.90 mg/g and a recovery rate of 94.98%, which were significantly higher compared to those of the non-imprinted polymer (0.47 mg/g and 39.67%, respectively). The material exhibited high selectivity for KCZ over structurally similar compounds. A high-performance liquid chromatography method with ultraviolet detection was developed and validated utilizing the synthesized MIP as a selective sorbent. The method displayed excellent linearity over a concentration range of 0.05-500 µg/mL, with a limit of detection of 0.193 µg/g, and a limit of quantification of 0.643 µg/g. These parameters indicate approximately a tenfold enhancement in sensitivity relative to previously reported ultrasound-assisted extraction methods. The method demonstrated excellent precision (relative standard deviation ≤ 6.06%) and high recovery rates (80.41%-98.86%) in real samples. Consequently, this study establishes a cost-effective, selective, and highly efficient approach for the determination of trace levels of KCZ in cosmetic products.

This work designs a titanium dioxide@covalent organic framework composite material (TiO₂-COF), which optimizes the distribution of lead adsorption sites by adjusting the position of hydroxyl groups in the COF, thereby enhancing the separation efficiency of trace Pb²⁺ ions. The composite material integrates the advantages of metal oxides and porous materials, optimizing the separation performance of Pb²⁺ ions through a synergistic enhancement effect. Additionally, its multi-interface structural characteristics provide the material with multidimensional selectivity, resulting in a highly selective separation material. In selectivity experiments, the material demonstrated high adsorption selectivity for Pb²⁺ ions compared to several other metal ions. Thermodynamic and kinetic simulation results prove that the adsorption of Pb²⁺ ions by TiO₂-COF conforms to the pseudo-second-order kinetics and the Langmuir adsorption model. After multiple cycles of use, the material still maintains high adsorption efficiency, demonstrating its potential clean and green application value in the highly selective separation of metal pollutants. The constructed material was used for the separation and preconcentration of Pb²⁺ ions, establishing a detection system for trace Pb²⁺ ions. The detection limit of the method is 0.073 µg L^-1 (3σ/K, n = 9), with precision ranging from 0.55% to 11.7% (n = 11), and a linear range of 0.2-5 µg L^-1, exhibiting strong anti-interference capability. The constructed method achieves the determination of lead ions in real samples, with recoveries ranging from 95% to 103%. Moreover, the standard material GBW08607 was analyzed through the constructed system, and the t-test shows that the calculated t-value is 2.01, which is less than the tabulated t-value of 2.57 (n = 6), proving the reliability of the method. It provides a potential alternative material for the separation and analysis of other environmental pollutants.

Comprehensive two-dimensional gas chromatography (GC×GC) offers exceptional separation performance, but method development remains time-consuming and sensitive to numerous system parameters. In this study, we present a modular simulation framework for GC×GC systems with thermal modulation, implemented in the open-source Julia package GasChromatographySystems.jl. The simulation is based on a graph-based abstraction of the GC system and models solute migration through column and modulator modules using previously established retention models. A simplified but effective model for thermal modulation enables the generation of realistic two-dimensional retention times and peak widths. Simulation results were validated against experimental measurements from a GC×GC-ToF-MS system using different modulation periods and temperature programs. Systematic deviations between simulated and measured retention times could be explained and corrected by adjusting parameters such as the actual modulation period and modulator shift. The final model achieved root mean squared error ($�\mathrm{rmse}$) of below 15 s (less than 1%) for first-dimension retention times and 55 ms (8%) for the second dimension. Peak width predictions were less accurate, with deviations of up to 3 s (40%) in the first dimension and up to 40 ms (60%) in the second. This modular and adaptable simulation framework provides a robust foundation for future applications in automated method development and system diagnostics in multidimensional gas chromatography.