Novel ion chromatography technique for the rapid identification and quantification of saturated and unsaturated low molecular weight organic acids formed during the Fenton oxidation of organic pollutants

The Fenton oxidation process is one of the most widely used technologies in the oxidation of organic pollutants. The identification and quantification of end products of these oxidation processes is of prime importance due to environmental concerns of pollution and toxicity. In this work, we have developed a highly sensitive, cheap, easy and rapid method of determining low molecular weight mono and dicarboxylic acids using ion exclusion chromatography with inverse chemical suppression and conductivity detection. Eleven organic acids were simultaneously separated in 22min with detection limits ranging from 10 to 500ppb and limits of quantification from 0.05 to 50ppm. The method was tested and proved to be accurate, reproducible, precise and highly sensitive. Linearity was in the range of R2: 0.977-0.999, with a percentage error of less than 2% for oxalic and maleic acids, and less than 1% for the rest of the organic acids studied.     

Characterization of carbonyl by-products during Uniblu-A ozonation by liquid chromatography/hybrid quadrupole time-of-flight/mass spectrometry

The structural elucidation of carbonyl-containing by-products arising from Uniblu-OH ozonation has been investigated by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) employing a quadrupole time-of-flight mass spectrometer. The by-products were derivatized with 2,4-dinitrophenylhydrazine, allowing the formation of [M-H](-) ions of the derivatives in the electrospray source. Exact mass measurements of both the [M-H](-) ions and their product ions allowed the elemental formulae and related structures of ten by-products to be determined confidently. The main degradation pathway were decarboxylation followed by further oxidation. It is noteworthy that the experimental procedure employed allowed the identification of both nitrogen- and sulphur-containing carbonyl by-products during Uniblu-OH ozonation. This result is of environmental relevance for monitoring the balance of organic nitrogen and sulphur during the ozonation of organic pollutants. These atoms, in fact, do not undergo complete mineralization.     

Serial coupling of RP and zwitterionic hydrophilic interaction LC–MS: Suspects screening of diclofenac transformation products by oxidation with a boron‐doped diamond electrode

The presence of pollutants and their transformation products (TPs) in the water system is a big concern because of possible adverse effects on the aquatic environment. Their identification is still a challenge that requires the combination of different chromatographic techniques. In the current research, serial coupling of RPLC and zwitterionic hydrophilic interaction LC with TOF‐MS was investigated as a single separation technique for the screening of suspected TPs from electrochemical oxidation of diclofenac using a boron‐doped diamond electrode. Diclofenac oxidation was performed in three water matrices in order to study its transformation in different chemical contexts. 47 TPs resulting from similar oxidation methods were selected from the literature. As in most cases standards were not available, an identification procedure based on accurate mass data and chromatographic behavior was proposed. According to this procedure, 11 suspected TPs, previously analyzed by LC, GC, or ion chromatography, were detected in a single injection. The method was proved to be reliable and versatile and it could be efficiently employed as a comprehensive analytical tool for the simultaneous analysis of compounds in a wide polarity range.     

Photodegradation of organic pollutants catalyzed by iron species under visible light irradiation

The green oxidation technology is the most economically attractive and environmentally friendly oxidation technique in the treatment of organic pollutants. Photocatalytic degradation of organic pollutants by iron species is a desired green oxidation technique due to using hydrogen peroxide or ideally molecular oxygen as oxidant and water as solvent. However, the system has some disadvantages. The reaction has to be performed in acidic conditions in order to avoid Fe ion precipitation and iron sludge will be accumulated in the reaction. Moreover, the utilization of H(2)O(2) means a high cost and risks in the storage and transportation and organic pollutants can not be completely mineralized. In this perspective, we report a systematic investigation of the improvement in the Fenton system for treatment of organic pollutants in water. Several strategies have been studied on the Fenton system for overcoming the above mentioned shortcomings and enhance the efficiency. For example, in order to extend the application of the Fenton system and perform it at neutral pH, iron complexes were used to replace the Fe(2+)/Fe(3+). Moreover, iron complexes have a strong absorption in the visible region, which leads to decomposition of colorless organic pollutants under visible light irradiation. Iron complexes with special structures can activate molecular O(2) instead of H(2)O(2) under mild conditions and the supported iron species maintains a high catalytic activity after repeated use and can be reused simply by filtration. Finally, prospects for further work required to be performed for its practical application is discussed.     

气相色谱-单光子电离飞行时间质谱的联用及在柴油组分表征中的应用

建立了一种气相色谱(GC)与单光子电离-飞行时间质谱(SPI-TOF MS)联用(GC/SPI-TOF MS)的分析方法。首先,设计了一种双层套管的传输管用于连接GC与SPI-TOF MS,实现了GC与单光子电离离子源的无缝连接。在此基础上,以n-十五烷标准品和苯/甲苯/二甲苯的标准气为对象,对电离源的重要电压参数进行了优化,得到了纯净的分子离子峰,实现了对各类有机物的快速和准确定性。最后,将该方法用于分析柴油中的挥发性与半挥发性有机物,获得了柴油组分的二维GC×SPI-TOF MS谱图。不需要复杂的谱图解析和数据处理,根据谱图中离子的质荷比(m/z)归纳了柴油的主要成分,包括脂肪烃、芳香烃和含量很低的苯并吡咯等含氮化合物;根据色谱的保留时间将柴油中的同分异构体区分开来。结果表明GC/SPI-TOF MS法是一种简单、有效的分析方法,非常适于柴油及复杂环境样品等的分析表征。     

溶剂浮选法分离富集污水中痕量羧酸类和胺类有机污染物的研究

本文报道了溶剂浮选法分离富集污水中痕量羧酸类有机污染物和胺类有机污染物的新方法。考察了溶液的pH值、通气速度、离子强度、浮选时间、相比以及不同溶剂对浮选效果的影响。在优化了浮选条件下溶剂浮选效率达到95％以上。采用本法对石化工业污水中的痕量羧酸类和胺类物质进行分离富集和鉴定,证明了该法的可行性。     

Heterogeneous oxidation of the insecticide cypermethrin as thin film and airborne particles by hydroxyl radicals and ozone

Evaluation of pesticides' fate in the atmosphere is important in terms of environmental effects on non-target areas and risk assessments analysis. This evaluation is usually done in the laboratory using analytical grade materials and is then extrapolated to more realistic conditions. To assess the effect of the pesticide purity level (i.e. analytical vs. technical) and state (i.e. sorbed film vs. airborne particles), we have investigated the oxidation rates and products of technical grade cypermethrin as thin film and in its airborne form, and compared it with our former results for analytical grade material. Technical grade thin film kinetics for both ozone and OH radicals revealed reaction rates similar to the analytical material, implying that for these processes, the analytical grade can be used as a good proxy. Oxidation products, however, were slightly different with two additional condensed phase products: formanilide, N-phenyl and 2-biphenyl carboxylic acid, which were seen with the technical grade material only. OH experiments revealed spectral changes that suggest the immediate formation of surface products containing OH functionalities. For the ozonolysis studies of airborne material, a novel set-up was used, which included a long-path FTIR cell in conjugation with a Scanning Mobility Particle Sizer (SMPS) system. This set-up allowed monitoring of real-time reaction kinetics and product formation (gas and condensed phases) together with aerosol size distribution measurements. Similar condensed phase products were observed for airborne and thin film technical grade cypermethrin after ozonolysis. Additionally, CO, CO(2) and possibly acetaldehyde were identified as gaseous oxidation products in the aerosols experiments only. A kinetic model fitted to our experimental system enabled the identification of both primary and secondary products as well as extraction of a formation rate constant. Kinetic calculations (based on gaseous products formation rate) have revealed values similar to that of the thin film experiments. Interestingly, heterogeneous oxidation of cypermethrin was also found to generate ultra fine secondary organic aerosols. Again, no significant difference was observed between analytical and technical grade materials. However, particle size distribution was much broader when films were exposed to OH and ozone than to ozone alone.     

Microwave-assisted extraction: Application to the determination of emerging pollutants in solid samples

Flame retardants, surfactants, pharmaceutical and personal care products, among other compounds, have been the object of numerous environmental studies. In this chapter, the application of microwave-assisted extraction (MAE) in the development of analytical methods for several groups of organic compounds with growing concern as emerging pollutants has been considered. Compared to other extraction techniques, optimization of MAE experimental conditions is rather easy owing to the low number of influential parameters (i.e. matrix moisture, nature of the solvent, time, power, and temperature in closed vessels). The great reduction in the extraction time and solvent consumption, as well as the possibility of performing multiple extractions, increasing the sample throughput, can also be highlighted among MAE advantages. In summary, the study of several applications of MAE to environmental problems demonstrates that this technique constitutes a good alternative for the determination of organic compounds in environmental samples. It can be used as a rapid screening tool, and also to obtain detailed information on the sources, behaviour and fate of emerging pollutants in environmental matrices.     

Determination of polar organic compounds in atmospheric aerosols by gas chromatography with ion trap tandem mass spectrometry

A gas chromatography with ion trap mass spectrometry method has been developed and validated for the analysis of 27 polar organic compounds in atmospheric aerosols. The target analytes were low‐molecular‐weight carboxylic acids and methoxyphenols, as relevant markers of source emissions and photochemical processes of organic aerosols. The operative parameters were optimized in order to achieve the best sensitivity and selectivity for the analysis. In comparison with the previous gas chromatography with mass spectrometry procedure based on single ion monitoring detection, the tandem mass spectrometry technique increased the analytical sensitivity by reducing detection limits for standard solutions from 1–2.6 to 0.1–0.4 ng/μL ranges (concentrations in the injected solution). In addition, it enhanced selectivity by reducing matrix interferences and chemical noise in the chromatogram. The applicability of the developed method in air quality monitoring campaigns was effectively checked by analyzing environmental samples collected in the Po Valley (Northern Italy) in different seasons. The obtained results indicate that the ion trap mass spectrometer may be an ideal alternative to high‐resolution mass spectrometers for the user‐friendly and cost‐effective determination of a wide range of molecular tracers in airborne particulate matter.     

Trends in the monitoring of legacy and emerging organic pollutants in protected areas

Protected Areas (PAs) are locations for conservation, internationally recognized for their natural, ecological, and/or cultural values. Human presence in PAs is generally limited to minimal or banned exploitation of natural resources. However, different threats to PAs are evident as a result of short and long-range transport of organic pollutants of legacy and emerging concern. There has been a shift of interest in legacy pollutants such as persistent organic pollutants (POPs) to emerging compounds, resulting in a need for improved monitoring strategies in PAs. Here, we highlight the main advances in environmental analytical chemistry for legacy and emerging pollution monitoring in PAs. Trends in sampling, sample preparation and instrumental determination of multiclass organic pollutants in biotic and abiotic matrices are presented and discussed. Here, we considered the most relevant and recent literature regarding organic pollutants in PAs from terrestrial to aquatic landscapes collected within 2015 to the present time frame.     

Accelerated plasma degradation of organic pollutants in milliseconds and examinations by mass spectrometry

The rapid degradation of organic pollutants, process monitoring and online controlling to obtain advanced products and decreased by-products are great and challenging tasks in environmental treatments. Herein, an accelerated plasma degradation in milliseconds was achieved by combining electrospray-based acceleration and plasma-based degradation. Taking the degradation of chloroaniline as an example, 97% of the degradation can be achieved in milliseconds. The velocity distribution of droplets was determined to be 40–50 m/s after being degraded for 0.30 ms, which exhibited different degradation behaviors in different milliseconds. Simultaneously, by virtue of the real-time and on-line detection ability of ambient mass spectrometry, intermediates, by-products and advanced products were monitored. Therefore, degradation mechanisms for different degradation times were proposed, which would provide theoretical guidance on obtaining efficient and green degradation. The fabrication, examining and understanding of accelerated plasma degradation not only enlarged application of accelerated reactions, but also promoted green and efficient degradation for environmental treatments.     

Fenton及Photo-Fenton非均相体系降解有机污染物的研究进展

Fenton及photo-Fenton氧化法是一种有效的应用于环境污染物处理领域的高新氧化技术之一,对Fenton试剂的固定化可以减少铁离子的二次污染,提高催化能力和光利用率,及扩展pH等优势。本文综述了近年来Fenton及photo-Fenton非均相体系氧化降解有机污染物的研究状况。引用文献57篇。     

Evaluation of chlorinated by-products in drinking waters of Central Friuli (Italy)

Drinkable water supplied by aqueducts undergoes preliminar potabilization which, in Italy, is mainly accomplished by chlorine addition. The bactericidal action involved in this process is always accompanied by chlorination and oxidation of organic species (mainly humic and fulvic acids) naturally present in treated waters, so that many disinfection by-products (DBPs) are formed, such as trihalomethanes (THMs) and halo-acetic acids (HAA), which can represent a chemical risk for public health. The aim of this study was the monitoring of DBPs in drinking water disinfected by chlorination, supplied by four different aqueducts of Central Friuli (Italy). DBP evaluations were performed in water samples consisting of both input and output of disinfection plants. The results of analytical determinations were worked out to provide the THM and HAA parameters for disinfected waters, while in feeding waters the following different conventional parameters were adopted: (i) trihalomethanes formation potential (THMFP), (ii) halo-acetic acids formation potential (HAAFP) and (iii) UV absorbance at 254 nm (UV254). The quite moderate content of chlorinated products found in all samples considered highlighted the excellent quality of potabilized waters available in Central Friuli. Moreover, our results confirmed that the majority of DBPs formed when chlorine is used for water disinfection consists of THMs, while chlorites and chlorates prevailed when potabilization is accomplished by using chlorine dioxide. Finally, simple UV254 monitoring turned out to be a profitable approach for the determination of chlorinated by-products only when THMs prevail among DBPs.     

Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

Persistent organic pollutants (POPs) are major environmental concern due to their persistence, long-range transportability, bio-accumulation and potentially adverse effects on living organisms. Analytical chemistry plays an essential role in the measurement of POPs and provides important information on their distribution and environmental transformations. Much effort has been devoted during the last two decades to the development of faster, safer, more reliable and more sensitive analytical techniques for these pollutants. Since the Stockholm Convention (SC) on POPs was adopted 12 years ago, analytical methods have been extensively developed. This review article introduces recent analytical techniques and applications for the determination of POPs in environmental and biota samples, and summarizes the extraction, separation and instrumental analyses of the halogenated POPs. Also, this review covers important aspects for the analyses of SC POPs (e.g. lipid determination and quality assurance/quality control (QA/QC)), and finally discusses future trends for improving the POPs analyses and for potential new POPs.     

Determination of nitrated-polyaromatic hydrocarbons (nitro-PAHs) in environmental samples by high resolution chromatographic techniques

An analytical procedure is described for the fractionation of organic compounds present in environmental samples and the determination of nitro polyaromatic hydrocarbons (nitro-PAHs). Both low and high resolution liquid chromatography are employed for the prefractionation of the soluble organic fraction (SOF) extracted from particulate matter or gaseous pollutants collected on adsorption traps. High resolution gas chromatography is used to analyze four fractions containing alkanes, PAHs, nitro-PAHs, and other polar PAHs. Nitrogen-containing species are separated by GC and detected specifically using an alkali flame (NPD) detector. Flame ionization (FID) detection, GC-MS of positive ions, and negative ion chemical ionization MS of the whole fraction is used for the identification and quantitation of the various components. The composition of SOF extracted from particulate matter emitted from diesel exhausts is elucidated and a large number of nitro-PAHs identified by the combination of the various techniques.     

Recent advances in analytical methodologies based on mass spectrometry for the environmental analysis of halogenated organic contaminants

Halogenated organic contaminants, including legislated and potential persistent organic pollutants and their precursors, represent a major environmental concern due to their hazardous effects in humans and wildlife as well as their ability to bioaccumulate through the food chain, their high resistance to environmental degradation, and their long-range atmospheric transport potential. The monitoring of these compounds in the environment at ultra-trace concentration levels requires highly selective and sensitive analytical methodologies. The lack of reference step-by-step methods led to a high number of reliable determinations depending on analytes, the complexity of the sample, and available instrumentation. Thus, this review article is mainly focused on the last advances in the analytical methodologies for the determination of halogenated organic contaminants. Methodologies regarding sample treatment, chromatographic separation, and mass spectrometry analysis have been reviewed to finally highlight the future perspectives for the improvement of the analytical determinations of these compounds and the throughput of environmental control laboratories in this field.     

The potential of gas chromatography with microwave-induced plasma atomic emission detection (GC-MIP-AED) as a complementary analytical technique in environmental screening analysis of aqueous samples

With GC-MIP-AED as a complementary analytical technique to GC-MS, the reliable identification of many organic pollutants in water samples of the Nitra river has been made possible due to the additional information on the elemental composition of organic pollutants it provides. Some compounds, which have been identified by GC-MS in the scan mode after a MS-library search, can be confirmed by their element responses. Even where the identification of substances cannot be confirmed by their empirical formulas calculated by GC-MIP-AED due to insufficient peak intensities, integration problems or chromatographic interferences, it can be facilitated by the presence of one or more heteroatoms. Quantitative data of selected organic pollutants from GC-MIP-AED screening analysis after compound independent calibration can be obtained more easily than, and in good agreement with, quantitative results provided by target analysis (e.g. GC-MS in the SIM-mode). New self-developed macros are helpful tools for acquiring information on the elemental composition and concentration of organic pollutants analyzed by GC-MIP-AED. Received: 3 March 1997 / Revised: 11 June 1997 / Accepted: 11 June 1997     

The potential of gas chromatography with microwave-induced plasma atomic emission detection (GC-MIP-AED) as a complementary analytical technique in environmental screening analysis of aqueous samples

With GC-MIP-AED as a complementary analytical technique to GC-MS, the reliable identification of many organic pollutants in water samples of the Nitra river has been made possible due to the additional information on the elemental composition of organic pollutants it provides. Some compounds, which have been identified by GC-MS in the scan mode after a MS-library search, can be confirmed by their element responses. Even where the identification of substances cannot be confirmed by their empirical formulas calculated by GC-MIP-AED due to insufficient peak intensities, integration problems or chromatographic interferences, it can be facilitated by the presence of one or more heteroatoms. Quantitative data of selected organic pollutants from GC-MIP-AED screening analysis after compound independent calibration can be obtained more easily than, and in good agreement with, quantitative results provided by target analysis (e.g. GC-MS in the SIM-mode). New self-developed macros are helpful tools for acquiring information on the elemental composition and concentration of organic pollutants analyzed by GC-MIP-AED. Received: 3 March 1997 / Revised: 11 June 1997 / Accepted: 11 June 1997