Chinese Journal of Analytical Chemistry最新文献

Poly-ether ketone (PEEK) was modified to sulfonated poly-ether ketone (sPEEK) by sulfonation process with a degree of sulfonation 49.5%. Carbon nanotubes were acid-treated with sulfuric acid and nitric acid solution (3:1, v/v) for functionalization. sPEEK and sPEEK/c-CNT membranes were prepared by solvent casting method using dimethyl sulfoxide (DMSO) as solvent. The experimental part was conducted as per design of experiment employing response surface methodology consisting three factors, namely (A) c-CNT (wt.%), (B) mixing temperature (°C), and (C) sPEEK concentration (mg/mL). The ion exchange capacity was found to increase with c-CNT (wt.%). Fourier-transform infrared spectroscopy confirms the sulfonation of PEEK. X-Ray diffraction investigates the influence of the sulfonation in the crystal structure of the sPEEK and sPEEK/c-CNT. Scanning electron microscopy images show that c-CNTs are dispersed well in the sPEEK matrix. The results showed slightly increasing water uptake and swelling ratio of the composites membranes. The analysis of variance (ANOVA) revealed that c-CNT (wt.%) is highly affecting the responses. Proton conductivity of sPEEK specimen is about 23.9 mS/cm, which is significantly increased to 57.0 mS/cm for sPEEK/0.12 c-CNT (wt.%) membrane suggesting its application for fuel cell.

A smart glucose detection system based on organic electrochemical transistor and near field communication module was built to detect sweat sample. The system mainly consists of three parts: glucose sensor, electrochemical detection module and application. The basic three electrodes (gate, source and drain) were prepared by screen printing technology on the polyethylene terephthalate sheets selected as the substrate material. The gate electrode was multilayer modified with gold membrane, Prussian blue and glucose oxidase, and the channel between the source and drain was covered with a poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) film. The potential drop caused by the redox reaction of glucose on the gate electrode changed the response of source-drain current signal. The electrochemical detection module with near field communication function was customized to realize the functions of signal detection, amplification and data transmission. Conjunct with smart Android devices analyzed and processed the data stream from near field communication to display glucose test results. The high sensitivity attributed to the amplification function of the field effect device and high selectivity to the enzyme sensor realize the detection of glucose in simulated sweat, which paves the way to relevant glucose detection in diabetics without the need for invasive finger-stick blood sampling.

Micro-electro-mechanical system (MEMS) based mass spectrometry, MEMS mass spectrometry, emerges a new technique branch of miniature mass spectrometry. One of the main challenges hindering the development of MEMS mass spectrometry is the poor compatibility between the complex electrode structure of traditional ion optics and MEMS processes. This paper proposed a planar quadrupole mass filter utilizing a highly simplified stacked-layer structure and film electrodes, which is easy to fabricate with high precision by MEMS surface micromachining. The ion trajectory simulation model of the MEMS mass spectrometry chip involving all necessary ion optics was elaborated for investigating the preliminary performance of the planar quadrupole mass filter. By optimizing the crucial parameters such as the frequency of radio frequency voltage, the ratio of direct current voltage and radio frequency voltage, pre-pole length, main-pole length, and injection kinetic energy, the preliminary simulation result of planar quadrupole mass filter achieved a 1–2 Da peak width (at 50% of peak height) and 20–80% ion transmission efficiency. Importantly, the planar quadrupole mass filter demonstrated a maximum working pressure of 0.1 Pa (using air as the buffer gas), 100 times higher than that of conventional quadrupole mass filters, while maintaining a 0.7–1.8 Da peak width and ∼5% ion transmission efficiency. Additionally, to modify the theoretical formulas for the non-ideal quadrupolar field of planar quadrupole mass filter, a novel approach based on stability diagrams obtained by simulation was also introduced. The pretty good linearity (R²=1) between ion masses in the range of 10 to 100 Da and the corresponding radio frequency voltages was verified through the simulated mass spectra. Notably, the proportional coefficient of ion mass and radio frequency voltage exhibited a minimal 4% deviation between the simulated value (4.7132 V_0P/Da) and the calculated value (4.9036 V_0P/Da) through the modified formula. In conclusion, the preliminary simulation results demonstrated that the planar quadrupole mass filter possessed moderate performance, high-pressure tolerance, and excellent theoretical consistency, which proved it a promising technology of MEMS mass spectrometry. It can find applications in the fields of gas detection, including the rapid response to hazardous gas emissions and in situ detection of dissolved gases in the deep sea.

Panax ginseng flowers (PGF), a constituent of ginseng, possess medicinal value and are widely recognized as a functional food. Therefore, ensuring meticulous control of PGF quality has become increasingly significant. One effective method for assessing product quality is to analyze the volatile organic compounds (VOCs) present in PGF, which act as indicative markers. In this study, VOCs in PGF were analyzed using gas chromatography-mass spectrometry (GC-MS), employing four extraction methods: steam distillation (SD), supercritical fluid extraction (SFE), headspace solid-phase microextraction (HS-SPME), and static headspace sampling (SHS). The results revealed 103 annotated components using the area normalization approach, highlighting the major differences among the four extraction methods. The main sesquiterpenoid components of PGF, 1,6,10-dodecatriene, 7,11-dimethyl-3-methylene-, and (E)- were the only common components. The SD, SFE, HS-SPME, and SHS methods identified 67, 20, 38, and 18 components, respectively. These components accounted for 89.67%, 61.84%, 82.6%, and 50.3%, respectively, of the total volatile oil effluent peak areas. Additionally, each method extracted 11, 9, 8, and 8 components, with proportions exceeding 1% in the PGF extracts. Terpenoids were identified as the main VOCs in PGF, with the SD method showing the highest sesquiterpene content. Both HS-SPME and SHS methods contained sesquiterpenoids, which accounted for 61.471% and 22.708% of the total relative amount, respectively. Furthermore, the extraction capacity of the HS-SPME method is approximately three times higher than that of the SHS method. The volatile oil extract of PGF consists of main components such as alkanes, esters, sesquiterpenes, and steroids, with compound contents exceeding 1%. Our findings provide a theoretical foundation for the rational development of PGF resources.

PCDD/Fs in fly ash from municipal solid waste incineration (MSWI), pose significant health and environmental risks. Recent research has focused on using chemical inhibitors in the post-combustion zone to effectively inhibit PCDD/F formation. This study examined a new inhibitor, carbohydrazide (CHZ), by exploring its application techniques and mechanism for PCDD/F inhibition. A comparative analysis was conducted to identify the efficient CHZ addition method, by comparing the PCDD/F suppression effect by CHZ premixing and cofiring with refuse-derived fuel (RDF) and injecting into the flue gas. It was revealed that the premixing and cofiring of CHZ with RDF resulted in a 10.9% reduction in the formation of PCDD/Fs, demonstrating the effectiveness of the suppression of PCDD/F emissions. XRD analysis showed that the addition of CHZ led to the reduction of CuO to Cu₂O in bottom and fly ash, and thus deactivate the Cu-based catalysts. In addition, CHZ could also passivate the transition metal catalysts through coordination. Consequently, CHZ could be considered as a potential PCDD/F inhibitor during the combustion process.

The biochar (FS-PNBC) is prepared by pyrolyzing mixed biomass of fish scale and pine needle in varied proportions in a tube furnace. The biochar was characterized by a specific Brunauer-Emmett-Teller (BET) surface area analyzer, scanning electron microscope (SEM), Fourier infrared spectrometer (FTIR), and X-ray diffractometer (XRD). In a solution with an initial concentration of 60 mg/L, the adsorption of ciprofloxacin (CIP) by a 1:1 ratio of fish scale and pine needle co-pyrolyzed biochar (FS-PNBC1) reached 27.97 mg/g. The adsorption properties such as thermodynamics, kinetics, isothermal adsorption, and adsorption factors were investigated by batch experiments. The results indicate that FS-PNBC exhibits a significantly large specific surface area, abundant pore structure, and a high level of porosity. After approximately 180 min, adsorption equilibration was achieved in a pH=4 solution. The kinetic data was well-matched with a quasi-second-order model, suggesting that chemisorption plays a role in the adsorption process. Isothermal adsorption and thermodynamic results indicate that the adsorption of CIP by biochar is more consistent with the Freundlich model, which suggests multilayered non-homogeneous phase adsorption and an exothermic entropy-increasing reaction capable of proceeding spontaneously. FS-PNBC contains oxygen-containing functional groups, and through FTIR analysis, it was observed that hydrogen bonding, π-π bonding, and electrostatic interaction are closely linked to adsorption. This study demonstrates that biochar produced through the co-pyrolysis of fish scale and pine needle has the potential to serve as an efficacious adsorbent for extracting ciprofloxacin from wastewater.

Geopolymers, which are environmentally friendly materials with aluminosilicates as raw materials, are expected to replace cement in construction materials. Here, the effect of fumed silica (FS) on the properties of metakaolin (MK)-based geopolymer materials was investigated with MK, sodium silicate, and potassium silicate as the main raw materials; their microstructures were characterized, and their performance was tested. The geopolymer's compressive strength, particle size, and curing characteristics were measured with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy for microstructural analysis. The total dissolved solids (TDS) method was employed to study the geopolymer and evaluate the effect of the resulting gel products on TDS. The results revealed that the strength of 4% FS could reach 56.3MPa after 7 days of incorporation, and the strength increased by 20% and 12% compared with the 0% and 2% groups, respectively. Meanwhile, studying the microstructure of kaolin revealed that the best mechanical and physical properties were obtained when kaolin was calcined at 700°C. In addition, the mixture of alkaline activators increased the reactivity of MK, and the mixed alkaline-excited geopolymer from sodium silicate and potassium silicate exhibited enhanced matrix strength properties compared to the single alkaline activators. Overall, the inclusion of the FS material resulted in the optimization of the mechanical properties, confirming the improvement in the mechanical properties.

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory malady that predominantly affects the joints. Emerging evidence highlights the perturbation of intestinal microflora and its resultant metabolites as potential instigators of disruptions within the "gut-joint axis". These disruptions subsequently trigger localized or systemic immune responses, culminating in joint inflammation and consequent impairment. While the efficacy of natural compounds in managing RA has been increasingly recognized, the precise mechanisms underlying their actions within the 'gut-joint axis' remain incompletely elucidated. The primary objective of this comprehensive investigation is to assess the effects of the intestinal barrier, gut microbiota, and metabolites on the pathogenesis of RA. Moreover, it aims to delineate the mechanisms through which natural products exert their therapeutic effects on the treatment of RA, all within the framework of the 'gut-joint axis'.

Wugen decoction, a classic traditional Chinese medical diet, is widely used to prevent influenza A virus infection in China. However, the principal effective ingredients and potential mechanism of Wugen decoction remain unclear. Therefore, a systemic analysis-based approach combined with molecular docking and network pharmacology is used to elucidate the molecular mechanism of Wugen decoction in prevention of influenza A. The efficient bioactive and potential targets of Wugen decoction are initially retrieved from public databases and relevant references. To further analyze the core targets, a protein-protein interaction network is investigated through cluster screening, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, and Gene Ontology analysis. Then the binding behaviors between crucial bioactive ingredients and core targets are obtained via molecular docking. Quercetin, stigmasterol, beta-sitosterol, genistein, oxalic acid, and daidzein with higher degrees are collected and screened from the “Herb-Ingredients” network. Meanwhile, AKT1, IL1B, IL6, INS, TNF, and VEGFA are identified from cluster screening and topological investigation. The coincident targets are primarily concentrated to biological processes including hydrogen peroxide, cellular response to synapse, and molecular function to cysteine-type endopeptidase activity involved in tumor necrosis factor receptor binding. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis manifests that the signaling pathways related to influenza A prevention are closely associated with tumor necrosis factor receptor binding, RNA polymerase II sequence-specific DNA binding transcription factor binding, and protein phosphatase binding. Molecular docking results highlight that the effective ingredients can spontaneously bind with the core targets. In all, the present research comprehensively illustrates the potential mechanism of Wugen decoction against influenza A virus infection with the ‘multicomponent-multitarget-multipathway’ mode. This research also provides an effective approach to uncover the scientific basis of Wugen decoction within food and health care industries.