Aerosol‐Assisted Synthesis of Porous TiNxOy@C Nanocomposites

Porous TiN_xO_y‐based particles were synthesized by an aerosol spray process. At first, the starting sol solution containing the metal precursor and the nitrogen source is sprayed to form an aerosol that is subsequently pyrolysed at different temperatures. The obtained dried particles are an amorphous coordination “polymer” rich in carbon and nitrogen. These “glassy” particles are finally thermally treated at 800 °C, promoting the crystallization of the particles and the release of a major part of the carbon. As the particles keep their original shape, carbon loss and density increase during the crystallization step and lead to the development of an accessible pore structure. The process was analyzed and extended to the synthesis of other metal nitrides, such as VN and W₂N, thereby showing its general validity for the production of functional nanocrystalline nitride ceramics with high porosity still occupying a relatively small volume, and otherwise not easily accessible.     

Experimental study on synchrotron radiation photoionization of secondary organic aerosol derived from styrene ozonolysis

Secondary organic aerosol (SOA) produced by ozonolysis of styrene and other alkene compounds is a major part of fine particles in urban atmospheres. The atmospheric ozonolysis process of styrene is simulated in a smog chamber, and the formed SOA particles are detected on-line by a synchronous radiation vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) in this study. Through molecular ion peaks in the photonionization mass spectra of SOA and the corresponding photoionization efficiency curve, combined with off-line measurement verification of ultraviolet visible and infrared absorption spectra, it is determined that formaldehyde, formic acid, benzene, phenol, benzaldehyde, and benzoic acid are the main constituents of styrene SOA. These provide new information for studying the atmospheric ozonolysis oxidation mechanism of styrene. VUV-PIMS can get over complicated sample preparation procedures, secondary pollution, and other shortcomings of the off-line method and is a useful instrument to measure constituents and unveil the formation process of SOA particles.     

高压密闭消解-电感耦合等离子体质谱法测定青藏高原气溶胶样品中磷及其他18种元素

气溶胶中磷（P）的准确测定是评估磷沉降对青藏高原生态效应及磷的生物地球化学循环的重要前提。针对青藏高原气溶胶中磷含量低及滤膜单个样品量有限的特征,本文建立了高压密闭消解-电感耦合等离子体质谱法测定气溶胶中磷及其他元素含量的方法。电感耦合等离子体质谱法（ICP-MS）测得P元素的检出限为3.5 μg/L,优于电感耦合等离子体发射光谱仪（ICP-OES）的检测限（89 μg/L）,其他元素检出限均达到μg/L（ppb）级（0.013-36 μg/L）,部分元素如Co、Cd、Pb等达到ng/L（ppt）级（2-7 ng/L）。各元素线性关系良好,测定结果的相对标准偏差(RSD) < 5%,磷的加标回收在90-103%, 方法准确度和精密度满足分析要求。该方法成功地测定了青藏高原实际气溶胶样品中磷及其他元素,具有良好的可靠性和实用性。     

HO2非均相摄取系数的测量与参数化

HO₂自由基与环境大气气溶胶的非均相反应是HO₂自由基的重要汇之一,对大气氧化能力有重要影响,对大气颗粒物的物化性质等进一步产生影响。HO₂的非均相反应过程的定量描述对不同地区大气氧化性与臭氧生成能力等问题的探求具有重要意义。目前不同研究小组测量的摄取系数可相差3到5个数量级,深入探究不同条件下不同种类气溶胶对HO₂自由基的非均相摄取机制,对摄取机制进行参数化表达,并准确测量摄取系数是量化其环境影响的关键。本文深入介绍了HO₂非均相摄取的原理与参数化表达,总结了已有的研究结果与进展,对不同的影响因素进行总结分析,并对此领域未来的发展方向提出建议与展望。     

AgNP/Bi/Nafion‐modified Disposable Electrodes for Sensitive Zn(II), Cd(II), and Pb(II) Detection in Aerosol Samples

A new method for modifying electrodes with Ag nanoparticles (AgNPs) using electrospray deposition for sensitive, selective detection of Zn(II), Cd(II), and Pb(II) in aerosol samples when combined with Bismuth and Nafion coating and square‐wave anodic stripping voltammetry (SWASV) is reported. Carbon stencil‐printed electrodes (CSPEs) fabricated on a polyethylene transparency (PET) sheet were produced for an inexpensive, simple to fabricate, disposable sensor that can be used with the microliter sample volumes for analysis. Sensor performance was improved by modifying the electrode surface with electrospray‐deposited AgNPs. The use of electrospray deposition resulted in more uniform particle dispersion across the electrode surface when compared to drop‐casting. Using AgNP‐modified electrodes combined with Bi and Nafion, experimental detection limits (LODs) of 5.0, 0.5, and 0.1 μg L⁻¹ for Zn(II), Cd(II), and Pb(II), respectively, were achieved. The linear working ranges were 5.0–400.0 μg L⁻¹, 0.5–400.0 μg L⁻¹, and 0.1–500.0 μg L⁻¹ for Zn(II), Cd(II), and Pb(II), respectively. Interference studies showed Cu(II) was the only metal that interfered with this assay but inference could be eliminated with the addition of ferricyanide directly to the sample solution. This electrochemical sensor was applied for the simultaneous determination of Zn(II), Cd(II), and Pb(II) within source particulate matter (PM) samples collected on filters using an aerosol test chamber.     

Rapid separation and simultaneous quantitative determination of 13 constituents in Psoraleae Fructus by a single marker using high‐performance liquid chromatography with diode array detection

Psoraleae Fructus is one of the most popular traditional Chinese medicines. Coumarins, flavonoids, and meroterpenes are the main contributors to the biological activity of Psoraleae Fructus. In this study, a new method for the quality control of Psoraleae Fructus was developed, through the quantitative analysis of multicomponents by single marker with diode array detector. Thirteen components, including psoralenoside, isopsoralenoside, psoralen, isopsoralen, psoralidin, neobavaisoflavone, bavachin, corylin, isobavachalcone, corylifol A, bavachinin, bavachalcone, and bakuchiol were rapidly separated and identified within 12 min by the newly developed method. The feasibility and reliability of this method were corroborated. The method was also compared to the external standard method and detection by corona charged aerosol detector. The results of percent difference (%) and cos (θ) have shown that there were no significant differences observed between the quantitative analysis of multicomponents by single marker and external standard method analyses; psoralen and isopsoralen were undetectable with the corona charged aerosol detector due to their but the sensitivity for all the compounds except bakuchiol detected by corona charged aerosol detector are higher than those obtained by diode array detector. In addition, the newly method developed was applied to the quality evaluation of Chinese patent medicines containing Psoraleae Fructus.     

Analysis of Organic Compounds in Antarctic Snow and Their Origin

Abstract

Organic compounds extractable with n-hexane were identified and quantitatively determined in pack, surface and deep snow samples taken at different depths and collected at several altitudes above sea level from Antarctica during the 1993/94 Italian expedition. The comparison between the composition of organic compounds in snow and the ones in pack and sea-water samples pointed out that the three matrices substantially contain the same biogenic and anthropogenic organic compounds. The contribution of marine aerosol to organic content in the snow is confirmed by the enrichment ratios calculated for the more representative classes of identified compounds (n-alkanes, phthalates and low molecular weight alkylbenzenes). The changes in the composition of organic compounds in snow as the altitude increases seem to depend on the dimensional spectrum of the aerosol. Thus, smallest particles, richest in surfactant material, reach the highest altitudes.     

Collection and Identification of Trace Organic Compounds in Atmospheric Deposition from a Semi-Rural Site in the U.K.

Abstract

The collection of rainwater, aerosol and vapour samples at a semi-rural site in the UK was achieved using a PTFE-lined wet-only rainfall collector and a high-volume filter/adsorption trap air sampler, respectively. Analysis of atmospheric deposition revealed the presence of several hundred compounds, many of which were of anthropogenic origin, e.g.: PAH, phenols and alkylbenzenes. Amounts of compounds varied from low nanograms to tens of micrograms per litre in rainwater samples and from low picograms to high nanograms per cubic metre in aerosols. Phenolic compounds were the most abundant group of organics identified in rainwater and were present at total concentrations of >20μg1^?1 in some of the samples analysed. In the high-volume air samples most anthropogenic compounds were detected in the adsorbent rather than the filter extract. Seasonal variations in the PAH content of the adsorbent extracts were observed. The presence of siloxanes in the air samples was thought to be the result of contamination.     

Development and validation of a RP-HPLC method for Roflumilast and its degradation products

Roflumilast is a phosphodiesterase type 4 inhibitor that is administered orally as a long-term, in the clinical treatment of chronic obstructive pulmonary disease and asthma. Launched in 2010 for the European market, it currently does not have an official monograph. Here, a reproducible gradient RP-HPLC method was developed and validated for the separation and determination of Roflumilast in the presence of its six major degradation products. Separation was performed on a C₁₈ analytical column (250?×?4.6?mm, 5?µm) with a mobile phase-A of ACN and a phase-B of ammonium acetate buffer (5?mM, pH 4.2) containing triethylamine (0.5% v/v). The most effective RP-HPLC gradient program was determined to be 0/80, 35/10, 36/80, 40/80 (time in minutes/% mobile phase-B). The flow rate was 1.0?ml/min and the column temperature was 25°C. The success of separation of the degradation products with different chemical characteristics was obtained by extending the time of the gradient, changing the proportion of the mobile phases and increasing the velocity of the flow. Two detectors were evaluated for the identification of degradation products and Roflumilast: a diode-arrary detector and a charged aerosol detector. The inability of the charged aerosol detector to dectect one of the six degradation products indicated that the method developed with RP-HPLC and the diode-array detector was more suitable for Roflumilast analysis. The method was validated according to specificity, linearity, LOD, LOQ, accuracy, precision and robustness.     

Preliminary study on aerosol particle addition calibration method for on-line quantitative analysis of airborne radioactive particles with ICP-MS

An ambient aerosol concentration enrichment system coupled with ICP-MS for real-time monitoring of airborne radioactive particles is now under development. ICP-MS is very sensitive to sample introduction conditions, so it is necessary to develop an easy-use calibration method for on-line quantitative analysis in field application. In this paper, a calibration method using standard solution instead of monodisperse particles was established and validated preliminarily. First of all, four parameters for the method were determined experimentally, including: uptake flow rate and nebulisation efficiency of the Microconcentric nebuliser, nebulisation/transport efficiency of Aridus Desolvating Sample Introduction System, and Relative Sensitivity Factor between ¹⁵⁹?Tb and ¹⁷⁴?Yb. Then, monodisperse terbium nitrate particles were generated by a commercial Vibrating Orifice Aerosol Generator. Continuous aerosols of ytterbium nitrate droplets were nebulised from standard solution. They were mixed together, desolvated through the membrane dryer and introduced into ICP-MS for on-line analysis of terbium nitrate particles. The air sampled from nuclear environment was also introduced into ICP-MS to investigate the effect of flow rate on instrument responses. Finally, atom numbers of ¹⁵⁹?Tb in discrete terbium nitrate particles were determined using the calibration method and compared to the calculated value. Results show that when air flow rate increase from 10?mL?min^?1 to 100?mL?min^?1, the ratio of ¹⁵⁹?Tb ion count to ¹⁷⁴?Yb ion intensity keeps constant although instrument sensitivity decreases by a factor of 25. The relative standard deviation of ¹⁵⁹?Tb atom number measured is better than 18%. The discrepancy with the calculated value could be attributed to the over-estimation of atom number in the particles generated by VOAG because there was some liquid leakage in the VOAG.