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This study presents a novel boron‐difluoride complex‐based fluorescent nanofilm sensor capable of detecting sarin vapors in the environment by reporting an output fluorescence signal. The sensor's evaluation demonstrated an exceptionally low detection limit for sarin vapor, even in the presence of various interfering gases, with theoretical and practical limits of detection of 0.7 and 1 ppb, respectively. The sensor featured a rapid response time (less than 2 s), a broad linear detection range (1 ppb–1000 ppm), and superior selectivity for sarin vapor over a group of interfering analytes, outperforming existing sarin sensors. Mechanistic study indicates that the sensor's heightened sensitivity to sarin vapor is due to the robust affinity of nitrogen atoms within the core BODIQ unit for sarin. Additionally, the tetraphenylethylene structure with steric hindrance effectively inhibits the tight packing of BODIQ derivatives, and forms numerous microporous structures in the self‐assembled nanofilm, which are beneficial for the mass transfer, enhancing the sensor efficiency in detecting vapors. Furthermore, we have achieved the differentiation of sarin, diethyl chlorophosphate, and HCl vapor through the analysis of sensing kinetic. This fluorescent sensor opens new avenues for sustainable, low‐cost, and environment‐friendly portable devices, as well as for environmental monitoring and tracking applications. [ABSTRACT FROM AUTHOR]

Solvothermal synthesis is the predominant method for creating new structured covalent organic frameworks (COFs), yet it grapples with challenges in controlling shape and morphology. This issue is attributed to the unregulated solvent‐feeding process, which results in rapid polymerization and uncontrolled phase separation. Consequently, a two‐step solvent‐feeding process is reported for the solvothermal shaping of imine‐linked COF monoliths with hierarchical porosity. The synthesis conditions for COF powders reported in existing literature are directly utilized without extensive optimization; however, solvents are divided into two segments prior to feeding. A minor segment of solvents is employed to dissolve monomers, which polymerize in situ to form amorphous monoliths. Subsequently, the remaining organic solvent, along with an acetic acid aqueous solution, is added for crystallization. The versatility of this two‐step feeding process in producing COF monoliths is illustrated. The high‐quality COF monoliths demonstrate benzene uptakes ranging from 6.0 to 16.8 mmol g−1 at 298 K. This study confirms that the two‐step solvent feeding process can be effectively integrated with the conventional solvothermal method to enhance the solution‐processability of COFs. It is anticipated that this modified solvothermal approach can readily shape COFs to meet practical application requirements. [ABSTRACT FROM AUTHOR]

Gas chromatography (GC) is an important and widely used technique for separation and analysis in the field of analytical chemistry. Micro gas chromatography has been developed in response to the requirement for on-line analysis and on-site analysis. At the core of micro gas chromatography, microelectromechanical systems (MEMs) have the advantages of small size and low power consumption. This article introduces the stationary phases of micro columns in recent years, including polymer, carbon materials, silica, gold nanoparticles, inorganic adsorbents and ionic liquids. Preparation techniques ranging from classical coating to unusual sputtering of stationary phases are reviewed. The advantages and disadvantages of different preparation methods are analyzed. The paper introduces the separation characteristics and application progress of MEMs columns and discusses possible developments.

The effective detection of isopropyl methylfluorophosphonate (GB, sarin), a type of organophosphine poisoning agent, is an urgent issue to address to maintain public safety. In this research, a gas-sensitive film material, poly (4-hydroxy-4,4-bis trifluoromethyl)-butyl-1-enyl)-siloxane (SXFA), with a structure of hexafluoroisopropyl (HFIP) functional group was synthesized by using methyl vinylpropyl dichlorosilane and hexafluoroacetone trihydrate as initial materials. The synthesis process products were characterized using FTIR. SXFA was prepared on a 200 MHz shear surface wave delay line using the spin-coating method for GB detection. A detection limit of <0.1 mg/m3 was achieved through conditional experiments. Meanwhile, we also obtained a maximum response of 2.168 mV at a 0.1 mg/m3 concentration, indicating the much lower detection limit of the SAW-SXFA sensor. Additionally, a maximum response standard deviation of 0.11 mV with a coefficient of variation of 0.01 and a maximum recovery standard deviation of 0.22 mV with a coefficient of variation of 0.02 were also obtained through five repeated experiments. The results show that the SAW-SXFA sensor has strong selectivity and reproducibility, good selectivity, positive detection ability, high sensitivity, and fast alarm performance for sarin detection. [ABSTRACT FROM AUTHOR]

Microextraction by packed sorbent, a miniaturized form of the solid-phase extraction, is a new sample pretreatment technology mainly used for bioanalysis. In this work, self-made device was fabricated by packing C18 sorbent into a microinjection needle (50 μL) and then applied for the analysis of polychlorinated biphenyls in bovine serum followed by gas chromatography with mass spectrometry determination. Compared with conventional solid-phase extraction, the developed method bears many intriguing properties such as low consumption of the sample and organic solvent, time-saving and easy operation, which are of great interest and desire for bioanalysis applications. A series of parameters that affect the analytical performance, such as the type of elution, the aspirating/dispensing cycles of sample loading and elution, washing solution, and matrix effects, was investigated in detail. Under the optimized conditions, the proposed method presented a good linearity ( R ≥ 0.986) and satisfactory sensitivity and limits of detection (0.06-0.53 ng/mL) and quantification (0.20-1.77 ng/mL), respectively. In addition, satisfactory recoveries (60.0-91.4%) and accuracy (RSD ≤ 5.72%) were achieved after optimizing the conditions when applying the developed method to real sample analysis. The screening of polychlorinated biphenyls residues in bovine serum samples by the developed method demonstrated that the assay is ideally suited as a monitoring method for polychlorinated biphenyls residues in bioanalysis. [ABSTRACT FROM AUTHOR]

The surface morphology of viscoelastic-sensitive films significantly affects sensing characteristics of surface acoustic wave (SAW) sensors. Uniformity and compactness of the film surface directly influences detectability of the SAW sensor toward target gases. Viscoelastic fluoroalcoholpolysiloxane (SXFA) was prepared in this work using spin coating technology on an SAW delay line of 200 MHz and then used as coating for detection of dimethyl methylphosphonate (DMMP). Polarizing, atomic force, and scanning electron microscopies confirmed the uniformity of the SXFA surface. The particle diameter in the cluster region was 10-15 μm. The contact angle (5.72-26.69°), surface tension (21.053-29.155 mN/m), Gibbs free energy (-160.68 to -153.45 J/m 2 ), and spreading coefficient (0.3028-6.9453 J/m 2 ) of different concentrations of SXFA were obtained through experiments, and their relation was analyzed using the Young T equation and Gibbs adsorption isotherm. The glass transition temperature (-19.7 °C) and elasticity of SXFA were also discussed. The consistency of sensor preparation was confirmed by detecting DMMP with five SAW sensors prepared simultaneously. Seven consecutive tests showed that the SAW sensor presents satisfactory repeatability (standard deviation, s , 1.134; coefficient of variance, v , 0.065; and population mean deviation, δ, 0.913) at a concentration of 1.71 mg/m 3 and acceptable linear relationship at a concentration range of 0.058-1.92 mg/m 3 , with a sensitivity of around 1.21 mv/(mg/m 3 ). The sensor exhibited outstanding sensitivity and satisfactory linearity and repeatability to DMMP. Meanwhile, the sensing mechanism in gas adsorption was also discussed in terms of LSER formulation and hydrogen bonding formation between SXFA and DMMP.

Hydrogen-bond acidic polymers are important high affinity materials sensitive to organophosphates in the chemical warfare agent sensor detection process. Interactions between the sensor sensitive materials and chemical warfare agent simulants were studied by inverse gas chromatography. Hydrogen bonded acidic polymers, i.e., BSP3, were prepared for micro-packed columns to examine the interaction. DMMP (a nerve gas simulant) and 2-CEES (a blister agent simulant) were used as probes. Chemical and physical parameters such as heats of absorption and Henry constants of the polymers to DMMP and 2-CEES were determined by inverse gas chromatography. Details concerning absorption performance are also discussed in this paper.