Advances in passive sampling in environmental studies

Passive sampling is based on the phenomenon of mass transport due to the difference between chemical potentials of analytes in a given environmental compartment and the collection medium inside a dosimeter. The subsequent laboratory procedure (i.e. extraction, identification and determination of analytes) is the same as in the case of classic sampling techniques.Passive sampling techniques are characterized by simplicity with regard to the dosimeter's construction as well as its maintenance. Therefore, they find ever increasing application in the field of environmental research and analytics. When choosing a passive sampling method, one should not forget that some passive samplers require the time-consuming calibration step before being used in the field.Novel solutions and modifications of existing sampler designs have been presented. Practical application of passive dosimetry in environmental analytics, including sampling of water, soil, air and other atypical media are discussed. Some aspects of calibration methods in passive dosimetry are also described. The latest trends in the application of passive sampling are highlighted.     

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.     

Current air quality analytics and monitoring: A review

This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main drawback is the lack of standard procedures. Telemonitoring is another approach to air monitoring, which offers some interesting opportunities, such as ease of coverage of large or remote areas, constituting a complementary approach to traditional strategies; however, it requires huge costs.     

表面增强拉曼光谱检测环境污染物的研究进展

随着环境问题的日益严重,环境污染物成为威胁人类健康和生态环境的世界性重大问题。表面增强拉曼光谱以其独特的“光谱指纹”、快速响应和无损分析等优点,成为检测环境污染物的一种有效工具。SERS基底的纳米结构和便携式拉曼光谱仪的发展将促进这一新兴检测技术在未来的快速现场检测中发挥重要作用。本文介绍了表面增强拉曼光谱应用于多环芳烃、农药、抗生素、重金属和大气颗粒物五个方面的检测技术研究进展,并提出了该技术在环境领域的可能发展方向,希望为相关领域的研究提供参考。     

Accurate quantification of freely dissolved organochlorine pesticides in water in the presence of dissolved organic matter using triolein-embedded cellulose acetate membrane

A novel method is described using triolein-embedded cellulose acetate membrane (TECAM) for accurate determination of the freely dissolved fraction of organochlorine pesticides (OCPs) in waters rich in dissolved organic matter (DOM). The performance of the method was tested with an air-bridge system for extracting OCPs from aqueous solutions with and without humic acid. In addition, the partition coefficients between humic acid and water (K _docs) for 20 OCPs were determined by TECAM with negligible depletion extraction. Results show that TECAM predominantly extracts the freely dissolved compounds and its extraction efficiency decreases significantly with an increase in concentration of humic acid in water. The proposed methodology is suitable for facile laboratory K _doc measurement for moderate to high hydrophobic compounds (log K _ow > 4). The linear relationship between log K _ow and log K _doc obtained in this study agrees well with the results reported earlier. The kinetic uptake rate constants (k _us) and TECAM–water partition coefficients (K _TECAMs) for the 20 OCPs were obtained using the controlled laboratory continuous-flow and static exposure system, respectively. These calibration parameters were used in the field experiment to estimate the freely dissolved concentrations of OCPs in the water of Taihu Lake in China. Our results show that TECAM can be used successfully to determine the freely dissolved OCPs in aquatic environments containing DOM, and the method is particularly suited for long-term water sampling. Figure Schematic diagram of water sampling with a triolein-embedded cellulose acetate membrane (TECAM)     

Air quality monitoring network design to control nitrogen dioxide and ozone, applied in Malaga, Spain

Air monitoring networks are necessary to assess air quality in order to reduce pollution to levels which minimize harmful effects on human health and the environment. This paper describes a method to design or optimize air quality monitoring networks for nitrogen dioxide and ozone and its application in Malaga, a medium large city located in Andalusia, southern Spain, with traffic being the main source of air pollution. The completion of this method revealed that the old assessment network in Malaga was badly designed and made it possible to determine that one traffic-orientated and one background control station were necessary for NO₂ assessment in Malaga, as well as two control stations for O₃. First the number of stations necessary is obtained from historical data. Sampling campaigns with passive diffusion samplers at 74 sites were then carried out to obtain information on the pollution distribution in Malaga. The average concentrations found for NO₂ and O₃ were 22.8 μg/m³ and 64.3 μg/m³ respectively. Maximum values of up to 42.2 μg/m³ NO₂ were found in Malaga city centre and O₃ reached 91.5 μg/m³ downwind from the emission source. After spatial interpolation of the obtained values with Geographical Information Systems, a selection of the best locations for the monitoring stations was made, in line with the macro- and microscale siting requirements of the European Directive 2008/50/EC on ambient air quality and cleaner air for Europe.     

An evaluation of ferrihydrite- and Metsorb™-DGT techniques for measuring oxyanion species (As,Se, V,P): Effective capacity,competition and diffusion coefficients

This study investigated several knowledge gaps with respect to the diffusive gradients in thin films (DGT) technique for measurement of oxyanions (As(III), As(V), Se(IV), Se(VI), PO₄³⁻, and V(V)) using the ferrihydrite and Metsorb™ binding layers. Elution efficiencies for each binding layer were higher with 1:20 dilutions, as analytical interferences for ICP-MS were minimised. Diffusion coefficients measured by diffusion cell and by DGT time-series experiments were found to agree well and generally agreed with previously reported values, although a range of diffusion coefficients have been reported for inorganic As and Se species. The relative binding affinity for both ferrihydrite and Metsorb™ was PO₄³⁻ ≈ As(V) > V(V) ≈ As(III) > Se(IV) ? Se(VI) and effective binding capacities were measured in single ion solutions, and spiked synthetic freshwater and seawater, advising practical decisions about DGT monitoring. Under the conditions tested the performance of both ferrihydrite and Metsorb™ binding layers was directly comparable for As(V), As(III) Se(IV), V(V) and PO₄³⁻ over a deployment spanning ≤2 days for both freshwater and seawater. In order to return quantitative data for several analytes we recommend that the DGT method using either ferrihydrite or Metsorb™ be deployed for a maximum of 2 days in marine waters likely to contain high levels of the most strongly adsorbing oxyanions contaminants. The high pH, the competitive ions present in seawater and the identity of co-adsorbing ions affect the capacity of each binding layer for the analytes of interest. In freshwaters, longer deployment times can be considered but the concentration and identity of co-adsorbing ions may impact on quantitative uptake of Se(IV). This study found ferrihydrite-DGT outperformed Metsorb-DGT while previous studies have found the opposite, with variation in binding materials masses used being a likely reason. Clearly, preparation of both binding layers should always be optimised to produce the highest capacity possible, especially for seawater deployments.     

Uncovering seasonal patterns of 56 pesticides in surface coastal waters of the Ria Formosa lagoon (Portugal), using a GC-MS method

This study describes the simultaneous quantification of 56 pesticides in surface coastal water, supported by the development and validation of a gas chromatography (GC)–ion trap (IT) mass spectrometry (MS) method. Samples (500 mL) were pre-concentrated 2500 times by solid phase extraction (OASISTMHLB). The compounds were identified and quantified, within 35 minutes, by GC tandem mass spectrometry (GC-MS/MS) and GC-MS, respectively. The methodology proved to be highly specific for all target pesticides, with an average linearity of 0.99. Detection limits and recovery rates ranged from 0.4 to 1.3 ng L^?1 and 71% to 120%, respectively. The performance of the method was checked using water samples collected from nine sampling sites along the Ria Formosa Lagoon Natural Park (south of Portugal, n = 54) in each season (2010). The total annual concentrations of all pesticides in each category (fungicides, herbicides and insecticides) were 1.4, 0.6 and 9.0 µg L^?1, respectively. Moreover, 89% of the pesticides tested for were detected, 84% could be quantified and 25% had concentrations above the European recommended levels (2013/39/EU). The highest total loads of pesticides were found in the spring, which is in agreement with their seasonal application. Physicochemical parameters such as, nitrites, nitrates, ammonia and phosphates, also indicate poor water quality, supporting the fact that the Ria Formosa lagoon actually needs an effective monitoring programme for effective preservation of its natural reserve status.     

Sensitive Solid Reagent For Formaldehyde,And A New Formaldehyde Generator

Abstract

A solid reagent of Purpald®-acetone aminal on sodium or potassium bicarbonate responds to formaldehyde in the sub-ppm concentration range. A purple color (λ=560 nm) is developed proportional to concentration of formaldehyde and time of exposure after wetting with a 90% acetone-10% water solution. The reagent should be of value as a semi-quantitative warning device for the presence of formaldehyde. A device is described which generates formaldehyde in air in the sub-ppm concentration range at room temperature with desired relative humidity. This generator could be used in the same manner to generate low concentrations of other substances of low volatility.     

Passive sampling and/or extraction techniques in environmental analysis: a review

The current state-of-the-art of passive sampling and/or extraction methods for long-term monitoring of pollutants in different environmental compartments is discussed in this review. Passive dosimeters that have been successfully used to monitor organic and inorganic contaminants in air, water, sediments, and soil are presented. The application of new approaches to the determination of pollutants at the sampling stage is discussed. The main milestones in the development of passive techniques for sampling and/or extraction of analytes, and in biomonitors used in environmental analysis, are summarized in this review. Passive samplers and biomonitors are compared.     

Development of a new passive sampler based on diffusive milligel beads for copper analysis in water

A new passive sampler was designed and characterized for the determination of free copper ion (Cu²⁺) concentration in aqueous solution. Each sampling device was composed of a set of about 30 diffusive milligel (DMG) beads. Milligel beads with incorporated cation exchange resin (Chelex) particles were synthetized using an adapted droplet-based millifluidic process. Beads were assumed to be prolate spheroids, with a diameter of 1.6 mm and an anisotropic factor of 1.4. The milligel was controlled in chemical composition of hydrogel (monomer, cross-linker, initiator and Chelex concentration) and characterized in pore size. Two types of sampling devices were developed containing 7.5% and 15% of Chelex, respectively, and 6 nm pore size. The kinetic curves obtained demonstrated the accumulation of copper in the DMG according to the process described in the literature as absorption (and/or adsorption) and release following the Fick's first law of diffusion. For their use in water monitoring, the typical physico-chemical characteristics of the samplers, i.e. the mass-transfer coefficient (k₀) and the sampler-water partition coefficient (K_sw), were determined based on a static exposure design. In order to determine the copper concentration in the samplers after their exposure, a method using DMG bead digestion combined to Inductively Coupled Plasma – Atomic Emission Spectrometry (ICP-AES) analysis was developed and optimized. The DMG devices proved to be capable to absorb free copper ions from an aqueous solution, which could be accurately quantified with a mean recovery of 99% and a repeatability of 7% (mean relative uncertainty).     

A novel approach for monitoring of cyanobacterial toxins: development and evaluation of the passive sampler for microcystins

We have investigated the ability of an integrative sampler for polar organic chemicals to sequestrate a group of common and highly hazardous cyanobacterial toxins—microcystins. In a pilot experiment, commercially available passive samplers were shown to effectively accumulate microcystins after 7 days’ exposure in the field. To find the most efficient configuration for sequestration of microcystins, four different porous membranes (polycarbonate, polyester, polyethersulfone and nylon) and two sorbents (Oasis HLB and Bondesil-LMS) were evaluated in the laboratory experiments, where samplers of different configuration were exposed to microcystins (microcystin-RR and microcystin-LR) for 14 days under steady conditions. We observed differences in sampling rates and amounts of accumulated microcystins depending on the sampler configurations. The samplers constructed with the polycarbonate membrane and Oasis HLB sorbent (2.75 mg/cm²) provided the highest sampling rates (0.022 L/day for microcystin-RR and 0.017 L/day for microcystin-LR). To the best of our knowledge, the present study is the first reporting application of passive samplers for microcystins, and our results demonstrate the suitability of this tool for monitoring cyanotoxins in water.     

Assessment of Chemcatcher passive sampler for the monitoring of inorganic mercury and organotin compounds in water

Abstract

Molecularly imprinted polymers (MIPs) for 4-nitrophenol have been successfully prepared by a thermal polymerization method using 4-vinylpyridine (4-VP) and ethylene glycol dimethacrylate (EDMA) as functional monomer and cross-linker, respectively. The obtained materials were evaluated with respect to their selective recognition properties for 4-nitrophenol by HPLC using organic and aqueous eluents. Furthermore, the specific binding sites that have been created during the polymerization process were analyzed via radioligand binding assays. The successful imprinting against 4-nitrophenol provides a new opportunity for advanced separation materials used in environmental analysis.     

Low temperature sampling techniques for the determination of less volatile compounds in gaseous mixtures

Summary The analysis of trace quantities of the less volatile polar compounds (H₂O, NH₃, HCN, amines, alcohols, esters etc.) is frequently seriously affected by dubious sampling procedures. In the present contribution two different sampling techniques at dry ice temperature (195 K) are described which both claim considerable and predictable efficacy. Depending on whether the matrices of the samples are still gaseous or condensable at 195 K and ambient pressure, a scrubbing technique may be used or condensation in the presence of a suitable solvent with subsequent evaporation of the matrix. Some solvents and solvent mixtures with FP<195 K are compiled. The normally disadvantageous low volatility can be exploited for enrichment. The scrubbing technique enables detection limits of 1 ppb(V/V) to be achieved, the condensation technique 1 ppm(m/m). Simple checking methods for both techniques are described. Thermodynamic considerations for ideal mixtures enable the calculation of upper limits for possible deviations. Examples are presented.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Chemometric interpretation of pesticide occurence in soil samples from an intensive horticulture area in north Portugal

An extensive monitoring programme of pesticides was carried out in soil samples from an intensive horticulture area in north of Portugal, putting into practice the needs for increased control of soil quality as far as organic pollution is concerned. The area under investigation was additionally defined as vulnerable to nitrates due to local soil and aquifer characteristics, which might be extended to pesticides contamination. Five sampling sites were selected and soils analysed at three depths in eight sampling campaigns, for the period of 2 years. A stepwise multivariate statistical approach was selected to uncover most relevant patterns inside a complex environmental data matrix. Cluster analysis was applied both to group pesticides and samples, giving a primary and unsupervised overlook of privileged relationships. Clusters of persistent pesticides and selected herbicides were identified, whereas sample classes were also formed and disposed geographically. Thirty eight percent of analysed soils samples fell into one class characterized by low contamination (class 1 in cluster analysis), which is entirely representative of the sampling site no. 1. Afterwards, linear discriminant analysis was applied to identify those pesticides, which had a higher impact in the definition of classes. Finally, factor analysis using a five component model was implemented in order to bring to light the constitution and data variance explained by each of the five main principal components, as well as, their relation to pest management practices. A factor was identified (PC1 – 22% variance) composed of chlorinated pesticides, which was representative of one of the investigated sites indicating its high contamination status. Qualitative main findings and class average concentration values were obtained through this multivariate statistical approach.     

Qualitative and quantitative analysis of polar pesticide multiresidues in leaf samples with a liquid chromatography–ion-trap mass-selective detector

Since 1995, in Austria, an agricultural programme (ÖPUL) has promoted an environmentally friendly and extensive production with restricted pesticide use. To observe the achievement of this goal, the pesticides in leaf samples are monitored. This study aimed to develop a multiresidue method for the qualitative and quantitative analysis of 46 pesticides in leaf samples with HPLC-IT-MS equipped with an electrospray ionization in positive mode after extraction with the QuECheRS method. The method has been validated for leaf samples based on the SANCO European Guideline at two fortification levels (LOQ and 10 times LOQ). The recoveries of the pesticides, with a few exceptions, were between 70 and 110% at both fortification levels and modes (full scan and selected reaction monitoring, SRM) with acceptable precision (RSD??1 and between 4.8 and 725?µg?kg^?1 in full scan, respectively) compared with the Austrian authorized value of 100?µg?kg^?1 fresh leaf sample defined in the ÖPUL programme.