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Superior photocatalytic activity of tungsten disulfide nanostructures: role of morphology and defects
摘要： Tungsten disulphide (WS2) nanostructures, WS2 nanosheets (WNS) and WS2 nanorods (WNR), were synthesized by varying the surfactant, N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB), concentration using facile hydrothermal technique. Samples were characterized by high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) for morphology, X-ray diffraction (XRD) to confirm their phase and crystal structure, photoluminescence (PL) and Raman studies for the determination of defect density, Tauc plot for the determination of band gap, Fourier transform infra red (FTIR) spectroscopy for functional groups and bonds, and Brunauer–Emmett–Teller (BET) isotherms for the determination of pore size and surface area. A comparative study using WS2 nanostructures (WNS and WNR) was conducted to observe the photocatalytic degradation efficiency (?) and degradation kinetics on methylene blue (MB) and 4-chlorophenol (4-CP). The superior photocatalytic performance of WNS over WNR is attributed to enhanced pore size and reduced defect density. High-performance liquid chromatography was carried out for the determination of intermediate products during photocatalytic degradation.
关键词： Raman,High-performance liquid chromatography,WS2 nanostructures,Photoluminescence,Photocatalysis
更新于2025-09-23 15:23:52
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Mass Production of High-Purity Semiconducting Carbon Nanotubes by Hydrochloric Acid-assisted Gel Chromatography
摘要： Mass production of high-purity semiconducting single-wall carbon nanotubes (s-SWCNTs) is critical for their application in the electronic and optoelectronic devices. Here we reported a method for the high-efficiency separation of high-purity s-SWCNTs with the acid-assisted gel chromatography, in which hydrochloric acid (HCl) was used to selectively oxidize metallic SWCNTs (m-SWCNTs) and enhance the difference in the interaction of metallic and semiconducting nanotubes with gel. Specifically, the concentration of HCl in the eluent was gradually increased to elute the carbon nanotubes adsorbed in the gel column step by step. The m-SWCNTs were firstly eluted at a low HCl concentration, and high-purity s-SWCNTs were selectively eluted at a higher HCl concentration. The final residues containing a relatively high content of m-SWCNTs and amorphous carbon impurities were left in the gel columns. Optical and electrical characterizations confirmed that the purity of the s-SWCNTs extracted from various raw SWCNT materials, especially CoMoCAT (7, 6), was improved greatly. Moreover, multiple single-chirality SWCNTs were firstly separated from the purified semiconducting CoMoCAT (7, 6) nanotubes. Our present work provides a simple and controllable way for the mass separation of high-purity s-SWCNTs and single-chirality species, which would accelerate their application in the field of electronics, optoelectronics and bio-imaging.
关键词： hydrochloric acid,separation,gel chromatography,Semiconducting carbon nanotubes,single-chirality
更新于2025-09-23 15:23:52
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Rapid and sensitive detection of formaldehyde using portable 2-dimensional gas chromatography equipped with photoionization detectors
摘要： We developed an automated and highly portable device for rapid and sensitive formaldehyde detection based on heart-cutting 2-dimensional gas chromatography. In this design, the air sample was first absorbed by a preconcentrator before it is injected into the 1st-dimensional column (Rtx?-VMS). The partial elution from the 1st-dimensional column containing formaldehyde was re-injected into the 2nd-dimensional column (Rt? Q-BOND column) for further separation. The detection of formaldehyde was achieved by using a micro-helium dielectric barrier discharge photoionization detector that is able to ionize formaldehyde (ionization potential = 10.88 eV). Due to the use of many miniaturized components, the entire system has a weight of only 1.3 kg (excluding the helium cartridge) and dimensions of only 27 cm x 24 cm x 12 cm. It is capable of detecting formaldehyde down to 0.5 ppb (V/V) with a signal-to-noise ratio of 6 in only 11 min (including 6 min of sampling). Meanwhile, simultaneous separation and detection of other air pollution related toxic compounds, such as benzene, toluene, ethylbenzene, and xylene, was also demonstrated by the 1-dimensional column and a flow-through micro-photoionization detector. The device developed here should have a broad range of applications in environmental protection, industries, space exploration, and battlefield.
关键词： Gas chromatography,Air quality control,Indoor air analysis,Photoionization detector,2D GC,Formaldehyde detection
更新于2025-09-23 15:23:52
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High-Performance Chromatographic Characterization of Surface Chemical Heterogeneities of Fluorescent Organic–Inorganic Hybrid Core–Shell Silica Nanoparticles
摘要： In contrast to small-molar-mass compounds, detailed structural investigations of inorganic core–organic ligand shell hybrid nanoparticles remain challenging. The assessment of batch-reaction-induced heterogeneities of surface chemical properties and their correlation with particle size has been a particularly long-standing issue. Applying a combination of high-performance liquid chromatography (HPLC) and gel permeation chromatography (GPC) to ultra-small (<10 nm diameter) poly(ethylene glycol)-coated (PEGylated) fluorescent core–shell silica nanoparticles, we elucidate here previously unknown surface heterogeneities resulting from varying dye conjugation to nanoparticle silica cores and surfaces. Heterogeneities are predominantly governed by dye charge, as corroborated by molecular dynamics simulations. We demonstrate that this insight enables the development of synthesis protocols to achieve PEGylated and targeting ligand-functionalized PEGylated silica nanoparticles with dramatically improved surface chemical homogeneity, as evidenced by single-peak HPLC chromatograms. Because surface chemical properties are key to all nanoparticle interactions, we expect these methods and fundamental insights to become relevant to a number of systems for applications, including bioimaging and nanomedicine.
关键词： surface chemistry heterogeneity,high-performance liquid chromatography,nanoparticle characterization,nanoparticle surface functionalization,fluorescence correlation spectroscopy,molecular dynamics,nanoparticle heterogeneity
更新于2025-09-23 15:23:52
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Intricacies of the Determination of the Radiochemical Purity of 68Ga Preparations: Possibility of Sorption of Ionic 68Ga Species on Reversed-Phase Columns
摘要： The results of studying 68Ga radiopharmaceuticals using various TLC and HPLC procedures are compared. The data obtained reliably show that a part of 68Ga ionic species are irreversibly (under definite conditions) sorbed onto chromatographic columns packed with С18 reversed phase. The loss of 68Ga ionic species in the analysis can reach 90%. The 68Ga loss increases with an increase in pH of the preparation. At pH 2.5–3.0, the total loss of 68Ga ionic species on the chromatographic column does not exceed 15%. At pH 4.0, it is 65 ± 7% on the average, and at pH 6.0 it reaches 87 ± 8%. This effect should be taken into account in analysis of any 68Ga radiopharmaceuticals.
关键词： radiochemical purity,radiopharmaceuticals,sorption,complexation,HPLC,quality control,chromatography,gallium-68
更新于2025-09-23 15:22:29
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Green method by diffuse reflectance infrared spectroscopy and spectral region selection for the quantification of sulphamethoxazole and trimethoprim in pharmaceutical formulations
摘要： An alternative method for the quantification of sulphametoxazole (SMZ) and trimethoprim (TMP) using diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and partial least square regression (PLS) was developed. Interval Partial Least Square (iPLS) and Synergy Partial Least Square (siPLS) were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. Fifteen commercial tablet formulations and forty-nine synthetic samples were used. The ranges of concentration considered were 400 to 900 mg g-1 SMZ and 80 to 240 mg g-1 TMP. Spectral data were recorded between 600 and 4000 cm-1 with a 4 cm-1 resolution by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The proposed procedure was compared to high performance liquid chromatography (HPLC). The results obtained from the root mean square error of prediction (RMSEP), during the validation of the models for samples of sulphamethoxazole (SMZ) and trimethoprim (TMP) using siPLS, demonstrate that this approach is a valid technique for use in quantitative analysis of pharmaceutical formulations. The selected interval algorithm allowed building regression models with minor errors when compared to the full spectrum PLS model. A RMSEP of 13.03 mg g-1 for SMZ and 4.88 mg g-1 for TMP was obtained after the selection the best spectral regions by siPLS.
关键词： green analytical method,diffuse reflectance infrared Fourier transform spectroscopy,interval partial least squares (iPLS),chemometrics,synergy partial least squares (siPLS),high performance liquid chromatography
更新于2025-09-23 15:22:29
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Encapsulation of zinc phthalocyanine into bovine serum albumin aggregates
摘要： Artificial hybridization of molecules with proteins is beneficial for biomedical applications. Herein, we describe a novel method for encapsulation of zinc phthalocyanine (ZnPc) aggregates into bovine serum albumin (BSA) aggregates, but not monomeric BSA. This property is potentially useful for not only photodynamic or photothermal therapy but also development of a novel delivery system for hydrophobic drug molecules.
关键词： Gel-filtration chromatography,Photosensitizer,Aggregation,Bovine serum albumin,Phthalocyanine,Photodynamic therapy
更新于2025-09-23 15:22:29
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Simple, Rapid, and Sensitive Determination of Thiols by Liquid Chromatography with Fluorescence Detection
摘要： Thiol compounds are important for protecting cells from oxidative stress. One common method of quantifying thiols is liquid chromatographic separation with fluorescence detection of their derivatives. The pH and the concentration of tris (2-carboxyethyl) phosphine hydrochloride in the reaction medium were shown to have significant effects on the fluorescence intensity of five thiol compounds: cysteine, glutathione, and three phytochelatins. The optimal pH range for derivatization, as indicated by the maximum fluorescence intensities, was 7.75–8.0 for all of the evaluated thiols. The thiol derivative fluorescence increased and then decreased with the tris (2-carboxyethyl) phosphine hydrochloride concentration. In particular, the fluorescence intensities of all of the derivatives decreased by 96.5–99.9% when tris (2-carboxyethyl) phosphine hydrochloride levels were increased from 0.1 to 1 mmol L?1. We attributed these changes to preferential interactions between tris (2-carboxyethyl) phosphine hydrochloride and the thiol-specific fluorophore, monobromobimane. We describe herein a method, based on our optimized solution pH and tris (2-carboxyethyl) phosphine hydrochloride concentration, that is rapid (12 min) and boasts excellent recovery (91.3–102%), sensitivity (limit of detections, 17.8–75.2 pmol L?1) and precision (relative standard deviation values ≤1.03%) for the quantification of these thiol compounds in microalgal samples.
关键词： tris (2-carboxyethyl) phosphine hydrochloride,High-performance liquid chromatography (HPLC),thiol compounds,monobromobimane
更新于2025-09-23 15:22:29
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[Environmental Chemistry for a Sustainable World] Nanosensors for Environmental Applications Volume 43 || Development of Optical Sensor Strips for Point-of-Care Testing for Pesticide
摘要： Disposable or point-of-care sensors are a promising tool for low-cost and rapid sensing of analytes including pesticides. They find important applications in pesticide-contaminated food, agro-products, and water quality monitoring. This chapter highlights the implication and significance of pesticide residue identification in foodstuffs and overviews the most frequently engaged analytical techniques, and finally their benefits and limitations are discussed. Disposable strip-based biosensors have their intrinsic advantages and some disadvantages, but their cost-effectiveness and portability have turned them as a potential possibility for point-of-care (POC) testing of various pesticides. The fabrication of robust, low-cost, reliable, and sensitive sensors with the aid of both simple naked eye-based and portable readout-based detectors is the driving factor in this sensor’s technology area. The pending limitations can be overcome by adapting new specific recognition elements and better signal generative particles or systems. The integration of these devices with card readers or smartphones can make them more user-friendly and will provide more accurate quantitative information.
关键词： Organophosphates,Pesticide,Immunoassay,Aptamer,Biosensors,Immunochromatographic assay,Point-of-care,Antibody,Rapid detection,Nanosensors,Gas chromatography
更新于2025-09-23 15:21:01
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EXPRESS: Analysis of Natural Gas Using a Portable Hollow-Core Photonic-Crystal-Coupled Raman Spectrometer
摘要： The low accessibility of natural gas fields and transporting pipelines requires portable online analyzers of the composition of natural gas, ensuring nearly chromatographic precision and capable of in situ analysis of a wide range of gases, including infrared-inactive ones (hydrogen, oxygen, nitrogen, chlorine). We have developed an express method of gas analysis meeting all requirements for the analysis of natural gas and its derivative mixtures using a portable 532 nm Raman spectrometer rigidly connected to a hollow-core crystal photonic fiber.
关键词： hollow-core photonic crystal fiber,HC-PCF,Raman spectrometry,gas chromatography,natural gas,calibration gas mixture
更新于2025-09-23 15:21:01