Application of solid-phase microextraction for determination of organic vapours in gaseous matrices

This paper reviews the practical applications of solid-phase microextraction (SPME) in the analysis of organic vapours which are pollutants of atmospheric air, indoor air and workplace air. Applications to headspace of solids and liquids such as different waters, soils, food, etc., are also included. Problems related to calibration in SPME analysis of gaseous matrices are also dealt with. Calibration procedures and apparatus for generation of standard gaseous mixtures are described. Advantages and limitations of SPME based gas chromatographic methods of air organic pollutants are discussed.     

Model of absorption of pollutants from atmosphere by a rain

The aim of this study was to create a mathematical model of absorption of pollutants from atmosphere by a rain. The speed, acceleration, established speed of drops depending on time and height taking into account the air’s density were calculated. The process of absorption solids from atmosphere by drops with use of an efficiency of inertial catching of solids was considered. The dynamic absorption of gaseous pollutants was calculated. The results of the dynamic purification of the atmosphere from solids and sulfur dioxide were represented.     

Simultaneous (or sequential) determination of the total polyphenol index (or I280) and density in wines by flow injection

Flow injection methods for the determination of the total polyphenol index, the 'index 280' (I280) and dissolved solids in wines are proposed. The determination of the total polyphenol index is based on the Folin-Ciocalteu reaction in a basic medium and subsequent spectrophotometric detection at 750 nm. The direct measurement at 280 nm of the wine allows the determination of I280 with a simple manifold. The dissolved solids determination is based on the displacement of a light beam when the refractive index of the medium changes. This phenomenon, followed by a change in the absorbance in a photometric detector, usually takes place when an injected sample reaches the flow cell, and it is magnified on passage of the light beam in the radial direction instead of the more common axial direction. The use of a capillary (4 cm x 1.1 mm id) as the flow cell allows monitoring of the injected plug. A simple manifold coupled with a diode array spectrophotometer allows the determination of these parameters with a frequency of at least 90 h-1. Depending of the method adopted for the determination of polyphenols, Folin-Ciocalteu or I280, either a manifold different from that used for determining dissolved solids or the same, respectively, is required. The methods have been successfully applied to different wines and were substantiated well with official methods.     

Diagnosis of Air Pollution by Microwave Spectroscopy

A review is made of the current state-of-the-art of microwave spectroscopy, and of the feasibility of using this technique in the detection of gaseous pollutants in air. The possibility of applying ultraviolet, visible, and infrared spectroscopic methods to the microwave region is investigated. This is a relatively new application of microwave spectroscopy; only one work was done in the area before 1966, and no results from it were published.

Present experimental work, being done by the authors, is explained. This is divided into two phases. First, basic measurements are being made to determine the limits of pressure over which small concentrations of pollutants may be measured in air. Second, methods are being investigated for adapting the techniques of microwave spectroscopy to the detection of gaseous pollutants. Specifically, it is desired to develop an instrument which will quantitatively detect pollutants at atmospheric pressures. This instrument may be incorporated in a system for air pollution monitoring over large expanses from remote stations, or stack monitoring.     

Measurement of Gas Mixture Adsorption Equilibria of Natural Gas Compounds on Microporous Sorbents

Physisorption equilibria of multicomponent gases on microporous solids like zeolites or activated carbons are considered. In view of lack of reliable and simple methods to calculate mixture adsorption isotherms from pure component data, experiments are still indispensable. An overview of classical and new methods to measure multicomponent gas adsorption equilibria is given. Some of the basic concepts like the Gibbs excess mass and the absolute mass adsorbed underlying these methods are discussed. Experimental data and a class of new adsorption isotherms for inhomogeneous microporous adsorbents of fractal dimension will be given in another subsequent paper (ADSO 635-98) by the same group of authors.     

Influence of the active sites and structure of inorganic supports on the photoxidative cleavage of olefins with oxygen in dry media

The influence of the nature of active sites and the crystalline structure of solids on the photoxidative cleavage of adsorbed α-methylstryrene have been studied. On acid solids, oxidation to PhCOCH₃, takes place on electron-ecceptor sites. On basic solids it occurs on electron-donor sites. The microcrystalline solids are more active than the amorphous ones.     

Récents développements liés à l'enthalpie d'immersion

The two calorimetric methods of determination of the enthalpies of immersion and of wetting are described in this text. The equations linking the adsorption enthalpies to the immersion enthalpies and to the wetting enthalpies are derived. Three experimental examples are shortly described in order to give the experimental limits and ability of these techniques. In the second part, a general model for the interpretation of adsorption and wetting is developed. This model uses three parameters related to the dispersive, acid and basic components of the energy. Some experimental examples are given, in order to show that it is possible to compute the surface energy of divided solids. From these results, it is also possible to predict the macroscopic behaviour of these solids when facing pure fluids.     

固体激光质谱分析及其展望

本文扼要地介绍了固体激光质谱学问世20多年来的发展和现状。其中包括有:固体激光质谱的简介和特色;发展过程中有重要贡献科学工作者的主要成就;它的有关基本理论;从仪器和分析实践两个方面介绍其发展概况。文中还就上述几个方面列出带综论性文献,以便读者作进一步了解。最后作者还展望了今后固体激光质谱学的发展前景。     

Description of a Method for Automated Determination of Organic Pollutants in Water

Abstract

A method for automated determination of 73 organic pollutants in water is described. The compounds, which are key representatives for different types of pollutants are determined in two chromatographic runs. 11 halogenated aliphatic hydrocarbons are determined using capillary GC equipped with electron capture detector. The remaining pollutants, representing both basic/neutral and acidic compounds are determined by using GC/MS combined with an automated search computer program. The majority of the compounds have a limit of quantitation at 1 ig/1 or lower. The precision of the GC method is in the range of 1.8% to 4.3%, with an average of 3.2%. The precision for compounds determined by GC/MS is in the range of 1% to 38%, with an average of 14%.

So far 30 water samples representing both polluted fjord areas as well as effluents from municipal treatment plants, refineries, petrochemical industries and metallurgic industries have been analysed. The method has been found to be an interesting alternative to traditional methods for monitoring water quality, and has demonstrated its potential both as a screening method for detecting “hot spots” as well as for routine monitoring of specific hazardous compounds.     

Organic pollutants adsorbed on microplastics: Analytical methodologies and occurrence in oceans

The massive use of plastics in several products has generated microplastic debris worldwide. Besides their negative effect on marine organisms by ingestion, microplastics are a contamination vector due to their capacity to transport organic pollutants around our planet. To evaluate the magnitude of this issue, it is necessary to know what kinds of contaminants are adsorbed on microplastics, as well as their concentrations. In order to assess the adsorption and desorption of pollutants from microplastics, effective and reliable extraction procedures are required. In this overview, literature reports, in which extraction, separation and determination methods have been applied to analyse the organic pollutants adsorbed on microplastics, are revised and discussed. Furthermore, the worldwide occurrence of organic compounds found on microplastics in oceans is reviewed and the results obtained from different geographical areas and their global distribution trends are compared. Priority organic pollutants, such as polycyclic aromatic hydrocarbons, hexachlorocyclohexanes, polychlorinated benzenes, perfluoroalkyl substances or bisphenol analogues, have been widely found on microplastic samples. Future research that focuses on different kinds of emerging pollutants is required.     

Laboratory studies of organic peroxy radical chemistry: an overview with emphasis on recent issues of atmospheric significance

Organic peroxy radicals (often abbreviated RO(2)) play a central role in the chemistry of the Earth's lower atmosphere. Formed in the atmospheric oxidation of essentially every organic species emitted, their chemistry is part of the radical cycles that control the oxidative capacity of the atmosphere and lead to the formation of ozone, organic nitrates, organic acids, particulate matter and other so-called secondary pollutants. In this review, laboratory studies of this peroxy radical chemistry are detailed, as they pertain to the chemistry of the atmosphere. First, a brief discussion of methods used to detect the peroxy radicals in the laboratory is presented. Then, the basic reaction pathways - involving RO(2) unimolecular reactions and bimolecular reactions with atmospheric constituents such as NO, NO(2), NO(3), O(3), halogen oxides, HO(2), and other RO(2) species - are discussed. For each of these reaction pathways, basic reaction rates are presented, along with trends in reactivity with radical structure. Focus is placed on recent advances in detection methods and on recent advances in our understanding of radical cycling processes, particularly pertaining to the complex chemistry associated with the atmospheric oxidation of biogenic hydrocarbons.     

Affinity separation of enzymes from mixtures containing suspended solids

Agarose beads containing immobilized enzymes or affinity ligands have been made magnetically responsive by adsorbing freshly precipitated magnetite on their surface. These beads are used for affinity adsorption of proteins from complex mixtures containing suspended solids. The magnetically responsive beads and the unwanted (diamagnetic) solids are then separated by magnetic filtration. This magnetic adsorption scheme for direct affinity separation of enzymes from mixtures containing suspended solids is compared with a similar, but nonmagnetic, scheme in which the affinity matrix is supported on fiberglass cloth. The enzyme is allowed to adsorb in this matrix, and the matrix is simply removed physically from the suspension to achieve separation from the unwanted solids. The two methods seem comparable in their ability to separate a desired enzymatic activity. The magnetic methods are technically the more complex of the two, but are significantly the more rapid. The efficiency of separation of diamagnetic and ferrimagnetic solids in these biological systems by high gradient magnetic filtration is good.     

Chemometrics characterisation of the quality of river water

Within the period from autumn 1990 to spring 1999 (from October to April in each period) 207 samples were collected and the measurement of 19 physical and chemical variables of the Mura river, Slovenia, were carried out. These variables are: river flow, water temperature, air temperature, dissolved oxygen, deficit of oxygen, oxygen saturation index, chemical oxygen demand (COD) in unfiltered and filtered samples, and biochemical oxygen demand after 5 days (BOD5) in unfiltered and filtered samples, pH, conductivity, ammonium, nitrite, nitrate, and phosphate concentrations, adsorbable organic halogens (AOX), dissolved organic carbon (DOC), and suspended solids. For handling the results of all measurements different chemometrics methods were employed: (i) the basic statistical methods for the determination of mean and median values, standard deviations, minimal and maximal values of measured variables, and their mutual correlation coefficients, (ii) the principal component analysis (PCA), and (iii) the clustering method based on Kohonen neural network. The influences of season, month, sampling site, and sampling time on the pollutant levels were examined. Before 1993, the pulp and paper industry was the main source of pollutants because of large amounts of chlorine emission as a consequence of industrial treatment, the leaching of cellulose. After the year 1993, the technology was changed and the quality of the river water has improved. The improvement could be detected 1 year after the change of technology. For one part of water samples the river quality classes based on biological parameters were also determined. The correlation between the biologically determined quality classes and chemical measurements was sought. Consequently, the biological classification for the water samples based on the chemical analyses was studied.     

Assessing the Influence of Electrode Polarity on the Treatment of Poultry Slaughterhouse Wastewater

Electrochemical methods have been increasingly gaining popularity in the field of wastewater treatment. However, the performance of these methods can be highly affected by the polarity direction as determined by the electrodes arrangement (anode to cathode or cathode to anode); as well as the characteristics of the wastewater to be treated as determined by the type of wastewater. The presented research work investigated the relationship between polarity direction and the removal of pollutants from poultry slaughterhouse wastewater using titanium and aluminium electrode materials. In the first case, the wastewater was exposed to the Ti (anode)-Al (cathode) combination, whereas in the second case the wastewater was subjected to the Al (anode)-Ti (cathode) arrangement. The two cases were designed to see if the polarity direction of the chosen electrode materials affected the removal of pollutants. The removal efficiencies were computed as a ratio of the remaining concentration in the treated effluent to the concentration before treatment. It was observed that the production processes generate highly fluctuating wastewater in terms of pollution loading; for instance, 422 to 5340 Pt-Co (minimum to maximum) were recorded from color, 126 to 2264 mg/L were recorded from total dissolved solids, and 358 to 5998 mg/L from chemical oxygen demand. Also, the research results after 40 min of retention time showed that both electrode arrangements achieved relatively high removal efficiencies; Whereby, the aluminium to titanium polarity achieved up to 100% removal efficiency from turbidity while the titanium to aluminium polarity achieved a maximum of 99.95% removal efficiency from turbidty. Also, a similar phenomenon was observed from total dissolved solids; whereby, on average 0 mg/L was achieved when the wastewater was purified using the aluminium to titanium arrangement, while on average 2 mg/L was achieved from the titanium to aluminium arrangement. A little higher removal efficiency discrepancy was observed from ammonia; whereby, the aluminium to titanium arrangement outperformed the titanium to aluminium arrangement with average removal efficiencies of 82.27% and 64.11%, respectively.     

Polymer Networks: A Challenge to Theorist and Technologist

Polymer networks challenge a theorist to develop methods of their generation, describe their topology, and understand critical phenomena (gelation) during their formation. They challenge a technologist because of their unique properties based on their large-scale three-dimensional connectivity and their easy transformation of relatively low-viscosity liquids into crosslinked solids. Polymer networks challenge both, in that they are structurally very complex for the technologist who needs the theorist for understanding and controlling their structure and properties. Also, the theorist is challenged by problems appearing in technology which may initiate a basic reconsideration of the theories' assumptions. In this contribution, methods for modeling polymer network structures and their recent applications to relatively complex systems of technological importance are briefly discussed.     

Determination of Polynuclear Aromatic Hydrocarbons in Sediment Porewater by SPMD

The mobility and bioavailability of organic pollutants associated with sediment depend on the concentrations of these compounds in the porewater^[1]. To assessment and impact the effect of these kinds of organic pollutants on the benthic ecosystem, and the effect of these contaminates were released as a second pollution source, it is in important to know the accurate concentrations of these organic pollutants in sediment porewater^[2]. However, the available methods are not effective^[1]. In 1990,the Semi-permeable Membrane Devices (SPMD)^[3] have being used to passively sample bioavailable aqueous organic pollutants, such as PCBs,OCPs and other organic pollutants.     

环境中手性污染物对映体分析方法的研究进展

手性污染物对映体尽管具有相似的物理化学性质,但在环境中的吸附、转移、降解等过程往往存在一定差异。生态安全问题与人类健康密切相关,因此,对手性环境污染物进行对映体水平上的分离分析是十分重要的研究课题。目前,国内外对环境中的手性污染物已开展了相关研究,然而全面评述相关分析测定方法的新进展鲜有报道。本文主要对环境中手性污染物的种类以及近5年环境中手性污染物的分析检测技术如液相色谱-质谱联用法、气相色谱-质谱联用法、毛细管电泳法、超临界流体色谱-质谱联用法等进行了归纳、综述和展望,为后续手性污染物的分析检测提供依据和参考。     

Computer simulation of transformations in solids

Recent developments in molecular dynamics (MD) and Monte Carlo (MC) methods enable us to fruitfully investigate transformations in solids by employing appropriate potentials. The possibility of varying both the volume and the shape of the simulation cell in these simulation techniques is especially noteworthy. In this article we briefly describe some of the highlights of the recent MD and MC methods and show how they are useful in the study of transitions in monatomic solids, ionic solids, molecular solids (especially orientationally disordered solids), and glasses. The availability of reliable pair potentials will undoubtedly make these methods more and more useful for studying various aspects of condensed matter in the years to come.     

TiO2光催化氧化去除有机污染物的研究进展

本文综述了近年来TiO2光催化降解有机污染物的研究进展，讨论了各类 有机污染物光催化氧化反应的特点、影响反应速率的因素及光催化体系的改进。     

Heavy Metals Desorption from Synthesized and Natural Iron and Manganese Oxyhydroxides: Effect of Reductive Conditions

Reductive conditions in soils can lead to the dissolution of iron and manganese oxyhydroxides, releasing heavy metal pollutants (e.g., Pb and Cd) bound to them. The present study used hydroxylamine as a reducing agent. Laboratory batch experiments were conducted, varying pH and hydroxylamine concentrations, with artificially contaminated synthetic amorphous Fe(OH)(3s) and MnO(2) and with a polluted cultivated soil. Until conditions were reductive enough to dissolve solids, remobilization of metals depended on their surface complexation constant and readsorption of metal was possible. However, if conditions were sufficiently reductive, all solids were dissolved and metals were released into solution. A straightforward surface complexation model for cation desorption was carried out to support these results. Copyright 2000 Academic Press.