Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air: Part 1: Sorbent-based air monitoring options

Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Target compounds range in volatility from acetylene and freons to phthalates and PCBs and include apolar, polar and reactive species. Airborne vapour concentrations will vary depending on the nature of the location, nearby pollution sources, weather conditions, etc. Levels can range from low percent concentrations in stack and vent emissions to low part per trillion (ppt) levels in ultra-clean outdoor locations. Hundreds, even thousands of different compounds may be present in any given atmosphere. GC is commonly used in combination with mass spectrometry (MS) detection especially for environmental monitoring or for screening uncharacterised workplace atmospheres. Given the complexity and variability of organic vapours in air, no one sampling approach suits every monitoring scenario. A variety of different sampling strategies and sorbent media have been developed to address specific applications. Key sorbent-based examples include: active (pumped) sampling onto tubes packed with one or more sorbents held at ambient temperature; diffusive (passive) sampling onto sorbent tubes/cartridges; on-line sampling of air/gas streams into cooled sorbent traps; and transfer of air samples from containers (canisters, Tedlar^® bags, etc.) into cooled sorbent focusing traps. Whichever sampling approach is selected, subsequent analysis almost always involves either solvent extraction or thermal desorption (TD) prior to GC(/MS) analysis. The overall performance of the air monitoring method will depend heavily on appropriate selection of key sampling and analytical parameters. This comprehensive review of air monitoring using sorbent tubes/traps is divided into 2 parts. (1) Sorbent-based air sampling option. (2) Sorbent selection and other aspects of optimizing sorbent-based air monitoring methods. The paper presents current state-of-the-art and recent developments in relevant areas such as sorbent research, sampler design, enhanced approaches to analytical quality assurance and on-tube derivatisation.     

SPE/GC-MS/SIM法同时测定水中7类27种SVOCs的方法研究

通过优选色谱柱,进一步改进色谱分离条件,优化前处理方法,建立了一种快速、高效测定水中7类27种半挥发性有机污染物(SVOCs)的GC-MS方法。该法可分析的目标物种类多、前处理速度快、萃取溶剂用量少、环境污染小、色谱运行时间短,40 min内完成分析,适用于大批量样品检测。另外,使用基质匹配标准溶液配制标准曲线,减小了基质效应,采用分段法选择离子(SIM)扫描,可获取更高灵敏度。该方法的检出限为0.000 4~0.013μg/L,回收率为70.5%~92.8%,相对标准偏差(RSD,n=6)不大于11.2%。     

Determination of polyaromatic hydrocarbons in river water using a sorbent consisting of removable octadecyltrimethylammonium ions attached to cation exchange silica in conjunction with commercial C18 silica

An application that highlights the usefulness of a solid phase extraction sorbent having a removable surfactant "stationary phase" is introduced. Polyaromatic hydrocarbons (PAHs) efficiently trap on commercially available non-polar sorbents (i.e., C(18) silica). However, solvents that are necessary to break strong hydrophobic interactions between the analyte and sorbent are harmful and incompatible for direct introduction into a reversed phase liquid chromatographic setup. In the presented approach, the entire "stationary phase"-analyte association is removed, resulting in very efficient elutions with a final extract that is mild and reversed phase liquid chromatographic compatible. Commercial C(18) silica was placed adjacent to this sorbent to provide more efficient trapping of less hydrophobic PAHs. PAHs were preconcentrated from river water and were determined using fluorescence detection coupled to HPLC. Detection limits for all PAHs examined were in the sub [micro sign]g L(-1) level.     

Sorption of Arsenic Oxyanions from Aqueous Solution on Goethite: a Study of Process Modelling

In the course of researching methods of sampling and monitoring toxic metals (as arsenic ions) in water and wastewaters, we selected the use of sorption for in-depth examination. Among other things, sorption modelling was investigated by the mechanism of surface complexation in order to describe the process or even predict the outcome for the expected rate, and in general, to develop this detection technique for pollutants. This investigation will include the application of goethite mineral as the suitable metal ion sorbent and the use of appropriate computer software. The relative thermodynamic aqueous speciation of the solution, in similar experimental conditions, was also studied.     

Analysis of 2-aminoacetophenone in wine using a stable isotope dilution assay and multidimensional gas chromatography-mass spectrometry

The key compound in the wine off-flavor phenomenon "Untypische Alterungsnote" (UTA) is 2-aminoacetophenone (AAP). A new method for its quantitative analysis in wine is described. The analysis is based on solid phase extraction with LiChrolut EN as sorbent material followed by multidimensional gas chromatography coupled to mass spectrometry (MDGC-MS). Matrix effects due to the complex wine aroma composition could be overcome by an alkaline washing step of the extract and the use of selected ion monitoring as detection mode. Quantification is based on a stable isotope dilution assay using deuterated 2-aminoacetophenone as internal standard.     

Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air. Part 2. Sorbent selection and other aspects of optimizing air monitoring methods

Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Applications range from atmospheric research and ambient air monitoring (indoor and outdoor) to occupational hygiene (personal exposure assessment) and measuring chemical emission levels. Part 1 of this paper reviewed the main sorbent-based air sampling strategies including active (pumped) tube monitoring, diffusive (passive) sampling onto sorbent tubes/cartridges plus sorbent trapping/focusing of whole air samples that are either collected in containers (such as canisters or bags) or monitored online. Options for subsequent extraction and transfer to GC(MS) analysis were also summarised and the trend to thermal desorption (TD)-based methods and away from solvent extraction was explained. As a result of this trend, demand for TD-compatible sorbents (alternatives to traditional charcoal) is growing. Part 2 of this paper therefore continues with a summary of TD-compatible sorbents, their respective advantages and limitations and considerations for sorbent selection. Other analytical considerations for optimizing sorbent-based air monitoring methods are also discussed together with recent technical developments and sampling accessories which have extended the application range of sorbent trapping technology generally.     

固相膜萃取-超声解吸-气相色谱-质谱法分析水中酞酸酯类化合物

酞酸酯(PAEs)是一种常用的增塑剂,由于其广泛应用已经对环境造成了污染.本研究建立了固相膜萃取-超声解吸-气相色谱-质谱分析水中酞酸酯类化合物的方法.对萃取条件、解吸条件进行了优化,确定了最佳的实验条件.在水浴温度40℃,超声功率50%的条件下超声7 min,测定水中PAEs的检出限(S/N>3)在0.05 ~0.26 μg/L之间;对不同基质空白样品进行加标回收实验,回收率在76.2%~112.3%之间,相对标准偏差小于10%.     

Comprehensive description of the photodegradation of bromophenols using chromatographic monitoring and chemometric tools

A general procedure for the study of complex photodegradation processes of environmental pollutants based on chromatographic monitoring and chemometric method is proposed. The procedure consists of multiset data analysis of aliquots collected at different reaction times and injected in High-Performance Liquid Chromatography coupled to diode array detection and mass spectrometry (HPLC-DAD-MS). In this study, photodegradation of six bromophenols with different degrees of bromination has been investigated in order to find out their photodegradation pathways and kinetics and to show the potential of the procedure proposed. Multivariate curve resolution-alternating least squares (MCR-ALS) has been used to resolve chromatographic elution profiles and pure spectra of species involved in the photodegradation process and, hence, to elucidate the photodegradation mechanism and to propose the chemical structure of the main photoproducts. This study shows that chromatographic monitoring is the preferred option when photochemical systems with large number of components with similar spectra and kinetic evolution are analyzed. This work reveals the advantages of the double DAD and MS detection to provide mechanistic and structural information about these complex photodegradation processes.     

Research progress of rapid detection of typical environmental pollutants based on chromatographic technologiesEI北大核心CSCD

对复杂环境介质中的典型污染物进行快速、精准甚至远程连续自动的检测,是控制环境污染、确保环境和生态安全的重要前提。近年来,基于色谱技术的典型环境污染物快速检测方法发展迅猛,主要包括样品快速制备和目标物快速检测两方面。辅助萃取、快速液相萃取、QuEChERS等样品前处理方法具有萃取效率高、溶剂消耗少、操作简便快速等优点。快速检测技术可在几秒到半小时内提供检测结果,主要包括实验室和现场检测。本文综述了2019年以来基于色谱技术的典型环境污染物快速检测研究新进展。介绍了萃取技术和基于试验设计的样品快速制备,实验室快速检测、便携仪器现场检测及遥感技术远程检测,提出了色谱技术快速检测环境污染物的挑战和展望。     

Trace analysis of pollutants by use of honeybees, immunoassays, and chemiluminescence detection

Specific and sensitive analysis to reveal and monitor the wide variety of chemical contaminants polluting all environment compartments, feed, and food is urgently required because of the increasing attention devoted to the environment and health protection. Our research group has been involved in monitoring the presence and distribution of agrochemicals by monitoring beehives distributed throughout the area studied. Honeybees have been used both as biosensors, because the pesticides affect their viability, and as “contaminant collectors” for all environmental pollutants. We focused our research on the development of analytical procedures able to reveal and quantify pesticides in different samples but with a special attention to the complex honeybee matrix. Specific extraction and purification procedures have been developed and some are still under optimization. The analytes of interest were determined by gas or liquid chromatographic methods and by compound-specific or group-specific immunoassays in the ELISA format, the analytical performance of which was improved by introducing luminescence detection. The range of chemiluminescent immunoassays developed was extended to include the determination of completely different pollutants, for example explosives, volatile organic compounds (including benzene, toluene, ethylbenzene, xylenes), and components of plastics, for example bisphenol A. An easier and portable format, a lateral flow immunoassay (LFIA) was added to the ELISA format to increase application flexibility in these assays. Aspects of the novelty, the specific characteristics, the analytical performance, and possible future development of the different chromatographic and immunological methods are described and discussed.

Selective and sensitive detection of organic contaminants in water samples by on-line trace enrichment–gas chromatography–mass spectrometry

Liquid chromatographic (LC) type trace enrichment is coupled online with capillary gas chromatography (GC) with mass spectrometric (MS) detection for the analysis of aqueous samples. A volume of 1–10 ml of an aqueous sample is preconcentrated on a trace-enrichment column packed with a polymeric stationary phase. After cleanup with HPLC-grade water the precolumn is dried with nitrogen and subsequently desorbed with ethyl acetate. A fraction of 60 μl is introduced on-line into a diphenyltetramethyldisilazane-deactivated retention gap under partially concurrent solvent evaporation conditions and using an early solvent vapor exit. The analytes are separated and detected by means of GC–MS. The potential of the LC–GC–MS system for monitoring organic pollutants in river and drinking water is studied. Target analysis is carried out with atrazine and simazine as model compounds; the detection limits achieved under full-scan and multiple ion detection conditions are 30 pg and 5 pg, respectively. Identification of unknown compounds (non-target analysis), is demonstrated using a river water sample spiked with 168 pollutants varying in polarity and volatility.     

Boron nitride nanotubes as novel sorbent for solid-phase microextraction of polycyclic aromatic hydrocarbons in environmental water samples

Boron nitride nanotube (BNNT) is a novel material that shows potential ability in capturing organic pollutants. In this study, BNNTs fixed on a stainless steel fiber by a sol–gel technique were used as sorbent for solid-phase microextraction. Five polycyclic aromatic hydrocarbons with different numbers of aromatic rings were selected as target analysts. Gas chromatography coupled with tandem mass spectrometry was used for detection and quantitative determination. Under optimized conditions, the experimental results show a wide range of linearity (1 to 1,000 ng L^?1), less than 10.1 % repeatability of relative standard deviation, and low detection limits (0.08 to 0.39 ng L^?1). In addition, the fabricated fiber offered good thermal and chemical stability. The proposed method was successfully applied for the analysis of real water samples, and satisfactory results were obtained with relative recoveries ranging from 80.2 to 116.8 %. The results demonstrated that BNNTs could be used as sorbent for the analysis of environmental pollutants at trace levels.     

Simultaneous analysis of neutral and acidic pharmaceuticals as well as related compounds by gas chromatography-tandem mass spectrometry in wastewater

This work presents a new multi-residue analytical method based on solid phase extraction (SPE) with Oasis HLB sorbent, followed by gas chromatography tandem mass spectrometry (GC-MS/MS) for the simultaneous determination of a group of 10 acidic and neutral pharmaceuticals and related compounds in wastewaters. The typical derivation step was avoided, allowing the determination of acidic and neutral pollutants in a single analysis as well as providing a fast and easy method suitable for routine monitoring. Target pollutants include: anti-inflammatory drugs (ibuprofen, acetaminophen and diclofenac); an antiepileptic agent (carbamazepine); stimulants (caffeine and nicotine); an antiseptic (triclosan); a plasticizer (bisphenol A) and two of their more relevant metabolites (2,8-dichlorodibenzo-p-dioxin and 1,7-dimethylxanthine). Recoveries between 66 and 112% were achieved for all the target compounds (except for 2,8-dichlorodibenzo-p-dioxin). Good linearity was observed within the studied ranges (R² > 0.993). Acceptable intra and inter-day precision was obtained, with relative standard deviation between 2 and 18%. The application of the optimized MS/MS mode allowed method detection limits in the range of 0.2-16 ng/L, with the exception of ibuprofen (120 ng/L). Finally, the methodology was successfully applied to the analysis of hospital effluent samples. All target analytes were detected at concentrations between 1 ng/L and 83215 μg/L. Even in the absence of derivatization, all the analytes showed good peak shape, except acetaminophen, which exhibited peak tailing. However, the method proved to be repetitive and reproducible, and the peak shape did not represent a problem for the reliable quantification of this compound. For most of the analytes studied, the detection limits achieved compare well against values reported in previously published methods.     

Exposure to airborne formaldehyde: Sampling and analytical methods—A review

Air monitoring is the quantitative-qualitative assessment of the extent of pollutants. It is performed to ensure compliance with legislation and to evaluate control measures and mitigation solutions. There are numerous approaches to measure airborne formaldehyde (FA), ranging from passive sampling techniques to remote sensing devices. Research of sampling procedures and analytical methods was performed in a scientific database and on the web to offer a scenario of the devices and techniques that can be used to assess FA exposure. Moreover, in the design of FA assessment, some crucial aspects were considered, such as standard atmosphere generation for devices calibration. This review summarizes the tools and basics used in FA air monitoring, useful to organize a functional monitoring strategy for assessment of FA concentration levels. An insight into the sampling and analysis of FA is provided. Recent advances in solid sorbent technology allow analysts to use these devices coupled to chromatographic instruments. A comparison of the strengths and weaknesses of analytical methods (gas-/liquid-chromatography coupled with mass spectrometry or UV detection, chromogenic, colorimetric, electrochemical determination) and sampling devices (impregnated papers, solid sorbents, liquid sorbents, bubblers, impingers, micro-impingers, denuder samplers, sealed bags, canisters) methods are illustrated. This survey found that a monitoring strategy should be planned considering the most appropriate methodology in terms of costs and practicability. Therefore, it is necessary to know the aspects that can make the chosen strategy suitable and valid for the exposure scenario under investigation.     

电化学酶传感器在环境污染监测中的应用

电化学酶传感器是一种应用广泛的生物传感器,它将酶及其底物相互作用的特异性与电化学的强大分析功能相结合,已经被广泛应用于药理学、临床、食品、农业以及环境监测中。制备电化学酶传感器的关键步骤是酶的固定化,选择用于制备电化学酶传感器的合适的酶固定化方法,在传感器电子转移动力学、稳定性和重现性等方面起着主要作用。本文在阐述电化学酶传感器工作原理的基础上,简要介绍了用于电化学酶传感器制备过程中的酶固定化方法,重点讨论了电化学酶传感器在监测环境中广泛存在的有机污染物、无机污染物和重金属等方面的应用,并对电化学酶传感器的发展方向进行了展望。     

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.     

Recent progress in surface enhanced Raman spectroscopy for the detection of environmental pollutants

Surface enhanced Raman spectroscopy (SERS) has emerged as one of the most promising analytical tools in recent years. Due to advantageous features such as sensitivity, specificity, ease of operation and rapidity, SERS is particularly well suited for environmental analysis. We summarize here some considerations with respect to the detection of pollutants by SERS and provide an overview on recent achievements in the determination of organic pollutants, heavy metal ions, and pathogens. Following an introduction into the topic and considering aspects of sensitivity, selectivity, reproducibility and portability, we are summarizing applications of SERS in the detection of pollutants, with sections on organic pollutants (pesticides, PAHs and PCBs, explosives), on heavy metal ions, and on pathogens. In addition, we discuss current challenges and give an outlook on applications of SERS in environmental analysis. Contains 174 references.

Solid-phase extraction—Thermal desorption—Gas chromatography with mass selective detection for the determination of drugs in urine

Summary Solid-phase extraction (SPE) was combined with thermal desorption (TD) and gas chromatographic (GC) analysis to determine drugs in urine. The extrattion was performed inside a fritted GC liner using about 5 mg TENAX that was inserted into the liner on top of the frit. After extraction, the liner was placed into the injector of the GC and the analytes were thermally desorbed by using a programmed-temperature vaporiser. Several sorbent materials were investigated for the applicability of SPETD-GC analysis. TENAX proved to be the most suitable sorbent, since hardly any interferences were observed and acceptable absolute recoveries (73 and 74%) were obtained for lidocaine and diazepam. A mass selective detector (MSD) in the selected ion monitoring mode allowed detection of lidocaine and diazepam down to 0.5 ng·mL⁻¹ using 50μL urine. The use of only 5 mg of extraction material allowed rapid extraction, while a 10 m GC column provided a fast chromatographic system. As a results, the total analysis time was less than 20 min, including 5 min for drying the TENAX and 5 min for thermal desorption. Thus, SPETD-GC-MS appears to be a powerful tool for the rapid analysis of biological samples.     

Estimation of unsaturated hydrocarbon pollutants in air based on selective gas chromatography with ozone

Regular monitoring of toxic organic pollutants in air is a very important issue in environmental pollution control. Among these, unsaturated hydrocarbon pollutants (UHP) such as ethylene and beta-propylene and another 18 olefins are of prime importance. A very fast method for the individual identification of UHPs in air is proposed. This method is based on gas-chromatographic separation with selective detection of unsaturated organic compounds (UOC) and on the chemical reaction of UOC with ozone in the gas phase. In view of the mathematical model derived for this ozonation process, a comparison of FID-chromatogram and ozonogram can be carried out for identification of the contaminants. This identification can be performed without preliminary separation in the presence of the main components. The method provides a high sensitivity (< 0.005 to 0.72 mass %) and selectivity.