Dry ice-originated supercritical and liquid carbon dioxide extraction of organic pollutants from environmental samples

Packed in a high-pressure vessel and under calculated conditions, dry ice can be used as a source of carbon dioxide for supercritical CO₂ extraction or liquid CO₂ of organic compounds from environmental samples. Coupled with a fluid modifier such as toluene, dry ice-originated supercritical CO₂ (Sc CO₂) achieves quantitative extraction of many volatile organic compounds (VOCs) and semivolatile organic compounds (SOCs) including polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and polychlorinated biphenyls (PCBs) from solid matrices. Compared to contemporary manual or automated supercritical fluid extraction (SFE) technologies, this novel technique simplifies SFE to a minimum requirement by eliminating the need of a high-pressure pump and any electrical peripherals associated with it. This technique is highly suitable to analytical areas where sample preservation is essential but difficult in the sampling field, or where sample collection, sample preparation, and analysis are to be done in the field.     

Comparative tests on the efficiency of three methods of methylmercury extraction in environmental samples

Mercury is used in gold mining in the Brazilian Amazon and released in significant amounts to the environment as Hg⁰. After its oxidation it may be methylated, mainly in bottom sediments and in the rhizosphere of floating aquatic macrophytes. Methylmercury (MeHg) is highly bioavailable and subject to biomagnification. The objective of this work was to evaluate the efficiency of three methylmercury extraction techniques, applied to replicates of environmental samples (stream sediments from Floresta ­da Tijuca, Rio de Janeiro; and roots of the floating macrophyte Eichhornia crassipes from Lagoinha, Rio de Janeiro) previously incubated with ²⁰³Hg²⁺. Method A is based on acid leaching and extraction of Me²⁰³Hg in toluene. Method B uses alkaline digestion, extraction in dithizone–benzene and separation of organic and inorganic ²⁰³Hg dithizonates by thin‐layer chromatography (TLC). Method C consists in separating the Me²⁰³Hg from the sample matrix by distillation. Total ²⁰³Hg and Me²⁰³Hg were detected by gamma spectrometry or liquid scintillation. For both matrices, Me²⁰³Hg extraction efficiency was better for smaller samples (range: 0.08–0.5 g for sediment, 0.1–0.5 g for E. crassipes roots). For the sediment samples, the three selected methods presented similar Me²⁰³Hg extraction efficiencies: 7–13, 5–14 and 4–17% of total added ²⁰³Hg was found as MeHg for procedures A, B and C, respectively. For E. crassipes roots, on the other hand, a lower extraction efficiency was obtained for the procedure C (11–28% of total ²⁰³Hg present as Me²⁰³Hg) than for methods B (22–36%) and A (20–44%). In all the root samples prepared with procedure B, a strong and durable chemiluminescence effect was observed, which required measuring the final Me²⁰³Hg extracts by gamma spectrometry only. In the specific conditions we used, extraction via distillation required re‐extraction of Me²⁰³Hg in the distillate, due to the presence of traces of inorganic ²⁰³Hg in the latter. Copyright © 1999 John Wiley & Sons, Ltd.     

Supercritical fluid extraction of microbial phospholipid fatty acids from activated sludge

Supercritical carbon dioxide (scCO₂) extraction was applied for the determination of microbial phospholipid fatty acids (PLFA) in activated sludge. Quantification was performed by using gas chromatography–mass spectrometry (GC–MS). The highest extraction yields of PLFA, at a concentration of 7.28 nmol/mg-dry activated sludge, was obtained at a temperature of 80 °C, pressure of 25 MPa and 10% (v/v) methanol for a 15-min extraction time. ScCO₂ extraction results obtained in these conditions were comparable with those obtained by liquid organic solvent extraction (LSE) based on diversity and equalibility indices. The repeatability test showed that the relative standard deviation values were less than 13%. The experimental results show that the scCO₂ extraction saves time and uses much less organic solvent. In addition, scCO₂ extraction is a promising and alternative method for the analysis of microbial community structure in environmental assessment using the PLFA profile.     

Extracting syringe for extraction of phthalate esters in aqueous environmental samples

The use of the extracting syringe (ESy), a fully automated membrane-based extraction technique, for analysis of phthalate esters in complex aqueous samples has been investigated. The ESy, working as an autosampler that combines the extraction process and injection into the gas chromatograph (GC) in one single step, is placed on top of the GC equipped with a flame ionisation detector. The aqueous samples are loaded in a tray and automatically extracted by employing microporous membrane liquid-liquid extraction principle. After the extraction, the extract is directly injected into the GC's programmable temperature vaporisation injector. Six different phthalate esters were used as model compounds. Four extraction solvents were tested and the addition of sample organic modifier was examined.Toluene was the optimal solvent to use for extraction. Due to the large variation in polarity of phthalate esters, 50% methanol as organic modifier had to be added to the samples so as to extract the most nonpolar phthalate esters; di-2-ethylhexylphthalate and di-n-octylphthalate, whereas the other four relatively polar phthalate esters were extracted from unmodified samples. No significant difference between extraction of river water, leachate water from a landfill and reagent water was noted, except for minor deviations. The extraction time was 20 min for extraction of a 1-mL sample, resulting in a good linearity for all aqueous media investigated, good enrichment factors (54-110 folds) and low LOD values (0.2-10 ng mL⁻¹) and relative standard deviation (%R.S.D.; 0.9-3.7%).     

Preparation of alumina-coated magnetite nanoparticle for extraction of trimethoprim from environmental water samples based on mixed hemimicelles solid-phase extraction

In this study, a new type of alumina-coated magnetite nanoparticles (Fe₃O₄/Al₂O₃ NPs) modified by the surfactant sodium dodecyl sulfate (SDS) has been successfully synthesized and applied for extraction of trimethoprim (TMP) from environmental water samples based on mixed hemimicelles solid-phase extraction (MHSPE). The coating of alumina on Fe₃O₄ NPs not only avoids the dissolving of Fe₃O₄ NPs in acidic solution, but also extends their application without sacrificing their unique magnetization characteristics. Due to the high surface area of these new sorbents and the excellent adsorption capacity after surface modification by SDS, satisfactory concentration factor and extraction recoveries can be produced with only 0.1 g Fe₃O₄/Al₂O₃ NPs. Main factors affecting the adsolubilization of TMP such as the amount of SDS, pH value, standing time, desorption solvent and maximal extraction volume were optimized. Under the selected conditions, TMP could be quantitatively extracted. The recoveries of TMP by analyzing the four spiked water samples were between 67 and 86%, and the relative standard deviation (RSD) ranged from 2 to 6%. Detection and quantification limits of the proposed method were 0.09 and 0.24 μg L⁻¹, respectively. Concentration factor of 1000 was achieved using this method to extract 500 mL of different environmental water samples. Compared with conventional SPE methods, the advantages of this new Fe₃O₄/Al₂O₃ NPs MHSPE method still include easy preparation and regeneration of sorbents, short times of sample pretreatment, high extraction yields, and high breakthrough volumes. It shows great analytical potential in preconcentration of organic compounds from large volume water samples.     

Sample preparation of sewage sludge and soil samples for the determination of polycyclic aromatic hydrocarbons based on one-pot microwave-assisted saponification and extraction

A microwave-assisted sample preparation (MASP) procedure was developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge and soil samples. The procedure involved the simultaneous microwave-assisted extraction of PAHs with n-hexane and the hydrolysis of samples with methanolic potassium hydroxide. Because of the complex nature of the samples, the extracts were submitted to further cleaning with silica and Florisil solid-phase extraction cartridges connected in series. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene, were considered in the study. Quantification limits obtained for all of these compounds (between 0.4 and 14.8 μg kg⁻¹ dry mass) were well below of the limits recommended in the USA and EU. Overall recovery values ranged from 60 to 100%, with most losses being due to evaporation in the solvent exchange stages of the procedure, although excellent extraction recoveries were obtained. Validation of the accuracy was carried out with BCR-088 (sewage sludge) and BCR-524 (contaminated industrial soil) reference materials.     

Comparison of two extraction methods for the analysis of per- and polyfluorinated chemicals in digested sewage sludge

A rapid and reliable analytical method, based on ion-pair extraction, clean-up on Envicarb cartridge and detection by liquid chromatography–tandem mass spectrometry (LC–MS/MS), was developed for determination of 17 per- and polyfluorinated chemicals (PFCs) in digested sewage sludge. Envicarb cartridge and six labeled internal standards were selected for the elimination/reduction and correction of matrix effects, respectively. As a result, the matrix effect for perfluorooctane sulfonamides (FOSAs) and perfluorocarboxylic acids (PFCAs) with carbon chain length from C6 to C14 was lowered to a range of −14% to +28%. However, the matrix effect for other analytes was still great mainly due to the absence of appropriate internal standard. Mean recoveries of the target analytes based on matrix spikes, at different spike levels (10–300 ng/g), ranged from 70% to 169%. Relative standard deviations (RSDs) were in the range of 2–20% at different spike levels. The limit of quantification (LOQ) ranged between 0.6 and 30 ng/g. The method was successfully applied to several sewage sludge samples from wastewater treatment plants nearby Zürich, Switzerland. In addition, by comparing the accuracy and precision of ion-pair extraction method and methanol extraction method, we further demonstrated that the ion-pair extraction method can be used for the analysis of PFCs in sludge samples. To our knowledge, this is the first study to extract the PFCs in sewage sludge with ion-pair method and to find unsaturated fluorotelomer carboxylic acids (FTUCAs) in sewage sludge.     

竹炭为高效吸附剂的固相萃取分析环境水样中的痕量三氯生

建立了一种由竹炭作为固相萃取高效吸附剂富集环境水样中痕量三氯生的新方法. 研究并优化了几个影响富集效率的参数. 在优化条件下, 三氯生的检测限为0.08 μg/L, 在1～100 μg/L 范围内有良好的线性关系, 相对标准偏差为2.9% (n=7). 方法可应用于实际废水样品的分析.     

Supported liquid membrane extraction with single hollow fiber for the analysis of fluoroquinolones from environmental surface water samples

In this work, the simple analytical method for the determination of four fluoroquinolone antibiotics: ciprofloxacin, enrofloxacin, norfloxacin and danofloxacin, in environmental surface water samples is described. Sample pretreatment step was performed by the application of a technique based on supported liquid membrane extraction with the configuration of single hollow fiber (HF-SLM). The HPLC system with diode array detection was used for final analysis of studied analytes. Various parameters affecting the extraction efficiency during HF-SLM enrichment, such as type of membrane diluent, pH of donor (sample) and acceptor phases, as well as an enrichment time and salt content of sample were studied. Using the presented hollow-fiber extraction high recovery (70–80%) was achieved. It gave enrichment factor above 100. The detection limits in surface water samples, for the four target antibiotics, were at range 0.01–0.02 μg/l, when 10 ml samples were processed. The obtained results demonstrate the applicability of presented method for the selective extraction of fluoroquinolones in environmental water samples at ultratrace level. Errors, expressed as relative standard deviation (RSD) were below 8%, for all tested concentration levels.     

Clean-up techniques in the pressurized liquid extraction of abiotic environmental solid samples

Pressurized liquid extraction (PLE) uses high pressure and temperature to perform exhaustive extraction and is one of the extraction techniques widely used for determining contaminants in environmental solid samples. However, under these conditions, compounds from the matrix are also extracted. Therefore, clean-up strategies must be often applied to remove interferences and avoid matrix effect in the subsequent determination. There are different clean-up strategies that can be used in PLE, some of which are applied during the extraction procedure and some are applied to the PLE extract. The aim of this review is to critically discuss these clean-up techniques used in PLE of abiotic environmental solid samples in the last 10 years. We provide the readers with information about the weaknesses and strengths of each strategy so they can select the most suitable clean-up technique for a specific environmental analytical problem.     

Simultaneous extraction and purification of fucoxanthin from Tisochrysis lutea microalgae using compressed fluids

The marine microalga Tisochrysis lutea, a Haptophyta with a thin cell wall and currently used mainly in aquaculture is a potential source of several bioactive compounds of interest such as carotenoids. In the present study, the simultaneous extraction and purification of fucoxanthin, the main carotenoid from T. lutea, was optimized using pressurized fluid extraction followed by in‐cell purification. An experimental design was employed to maximize carotenoids’ extraction; the experimental factors chosen were: (i) percentage of ethanol/ethyl acetate (0–100 %), (ii) temperature (40–150°C), and (iii) number of static extraction cycles (1–3). The maximum carotenoids’ recovery, mainly fucoxanthin, was obtained with pure ethyl acetate at 40°C using one extraction cycle, achieving values of 132.8 mg of carotenoids per gram of extract. Once the optimum extraction conditions were confirmed, in‐cell purification strategies using different adsorbents were developed to obtain fucoxanthin‐enriched extracts. Activated charcoal showed potential retention of chlorophylls allowing an effective purification of fucoxanthin in the obtained extracts. Chemical characterization of extracts was carried out by reversed‐phase high‐performance liquid chromatography with diode array detection. Therefore, a selective fractionation of high value compounds was achieved using the proposed green downstream platform based on the use of compressed fluids.     

DNA purification from crude samples for human identification using gradient elution isotachophoresis

Gradient elution isotachophoresis (GEITP) was demonstrated for DNA purification, concentration, and quantification from crude samples, represented here by soiled buccal swabs, with minimal sample preparation prior to human identification using STR analysis. During GEITP, an electric field applied across leading and trailing electrolyte solutions resulted in isotachophoretic focusing of DNA at the interface between these solutions, while a pressure‐driven counterflow controlled the movement of the interface from the sample reservoir into a microfluidic capillary. This counterflow also prevented particulates from fouling or clogging the capillary and reduced or eliminated contamination of the delivered DNA by PCR inhibitors. On‐line DNA quantification using laser‐induced fluorescence compared favorably with quantitative PCR measurements and potentially eliminates the need for quantitative PCR prior to STR analysis. GEITP promises to address the need for a rapid and robust method to deliver DNA from crude samples to aid the forensic community in human identification.     

Fluidized-bed extraction of polycyclic aromatic hydrocarbons from contaminated soil samples

Summary Due to the carcinogenity and ubiquity of polycyclic aromatic hydrocarbons in the environment they are of ongoing interest to analytical chemistry. In this study, a comparison of the classic Soxhlet extraction and, fluidized-bed extraction, has been conducted. The extraction of polycyclic aromatic hydrocarbons by this technique has been optimized considering as experimental variables the variation of the number of extraction cycles and the holding time after reaching the heating temperature by means of a surface response design. The significance of the operational parameters of the fluidized-bed extraction on the performance characteristics has been investigated. For the determination of the analytes a selective clean-up of the extracts followed by a fast gas chromatography method with mass spectrometric detection was used, resulting in low limits of detection (0.2 pg μL⁻¹). The accuracy of the complete analytical method was established by extraction and analysis of reference materials.     

Occurrence of pharmaceuticals and their metabolites in sewage sludge and soil: A review on their distribution and environmental risk assessment

The recycling and recovery of organic matter and nutrients from sewage sludge for application in agricultural soils is gaining interest, while the presence of pharmaceutically active compounds (PhACs) in this matrix may have a great impact on the environment and human health. The aim of this review paper is to outline recent research on the occurrence of PhACs and their metabolites in sewage treatment lines. A total of 32 classes of therapeutic groups including 180 PhACs and 45 metabolites have been included. In a first part, a summary of the analytical methods with a critical overview of the extraction and determination techniques, quality control issues and methodological challenges for their determination is included. Subsequently, the study gives a snapshot of the concentration levels and distribution patterns found in primary, secondary, digested (aerobically and anaerobically), dehydrated and composted sludge. Data have been systematically summarized and categorized according to matrix type, treatment processes available for PhAC degradation in sludge, and geographical areas. Our literature review showed that antimicrobials, antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), antidepressants and antidiabetics were the most abundant PhACs found in sludge matrices.Overall, attenuation of PhACs concentrations occurs during sludge stabilization, in particular during anaerobic digestion and composting. PhAC sorption onto sludge is strongly affected by the physicochemical properties, the sludge matrix and the operating and environmental conditions. Lastly, the paper discusses the impact of PhACs on sludge-amended agricultural land. The potential ecotoxicological risk associated with the presence of PhACs in amended soil is medium-low for most PhACs. The most critical compounds found in sludge-amended soil are ciprofloxacin, 17α-ethinylestradiol, 17β-estradiol, and triclocarban and triclosan.     

A two-step electrodialysis method for DNA purification from polluted metallic environmental samples

Extracting DNA from samples of polluted environments using standard methods often results in low yields of poor-quality material unsuited to subsequent manipulation and analysis by molecular biological techniques. Here, we report a novel two-step electrodialysis-based method for the extraction of DNA from environmental samples. This technique permits the rapid and efficient isolation of high-quality DNA based on its acidic nature, and without the requirement for phenol-chloroform-isoamyl alcohol cleanup and ethanol precipitation steps. Subsequent PCR, endonuclease restriction, and cloning reactions were successfully performed utilizing DNA obtained by electrodialysis, whereas some or all of these techniques failed using DNA extracted with two alternative methods. We also show that his technique is applicable to purify DNA from a range of polluted and nonpolluted samples.     

Solid-phase extraction of room-temperature imidazolium ionic liquids from aqueous environmental samples

Owing to their favorable properties, ionic liquids have recently gained recognition as possibly environmentally benign solvents. Now among the most promising industrial chemicals, they have already been labeled green, but this appellation seems due entirely to their very low vapor pressure. This growing interest in the various applications of ionic liquids will soon result in their presence in the environment. Therefore, reliable analytical tools for the environmental analysis of ionic liquids need to be developed urgently. This paper presents a newly developed analytical procedure for the enrichment of 1-alkyl- and 1-aryl-3-methylimidazolium ionic liquids from water samples. The method is based on cation exchange solid-phase extraction followed by selective elution. Pre-concentrated samples are subjected to high-performance liquid chromatography (HPLC) with an advanced methodology for qualitative and quantitative analysis. The overall procedure was verified by using standard spiked samples of tap water, seawater, and freshwater.     

Ultrasonic solvent extraction of organochlorine pesticides from soil

Ultrasonic solvent extraction of the organochlorine pesticides (OCP) including α-, β-, γ- and Δ-hexachlorocyclohexane (HCH), heptachlor, aldrin, o,p′-DDE, dieldrin, p,p′-DDE, p,p′-DDT, methoxychlor, mirex from soil is reported. The extraction procedure was optimized with regard to the solvent type, amount of solvent, duration of sonication and number of extraction steps. Determination of pesticides was carried out by gas chromatography (GC) equipped with electron capture detection (ECD). Twice ultrasonic extraction using 25 mL of a mixture of petroleum ether and acetone (1/1 v/v) for 20 min of sonication showed satisfactory extraction efficiency. Recoveries of pesticides from fortified soil samples are over 88% for three different fortification levels between 15 and 200 μg kg⁻¹, and relative standard deviations of the recoveries are generally below 6%. Real soil samples were analyzed for OCP residues by optimized ultrasonic solvent extraction and shake-flask as well as soxhlet extraction technique. Investigated all extraction methods showed comparable extraction efficiencies. Optimized ultrasonic solvent extraction is the most rapid procedure because the use of time in ultrasonic extraction was considerably reduced compared to shake-flask and soxhlet extraction.     

Development and validation of methods for the trace determination of phthalates in sludge and vegetables

A routine method which is simple, quick and precise has been set up and validated for phthalate analysis in environmental samples (tomato plants and sewage sludges). Six phthalates have been studied simultaneously: dimethylphthalate, diethylphthalate, di-n-butylphthalate, n-butylbenzylphthalate, di-2-ethyl-hexyl phthalate (DEHP) and di-n-octylphthalate. Optimization of sample, solvent extraction uses a Soxtec apparatus and extract purification with an a solid-phase extraction cartridge allows between 90 and 110% recovery of phthalates. Precise, sensitive and selective identification and quantifying of analytes is by GC-MS in the single ion monitoring mode. This protocol allows analytes with concentrations as low as 10 microg/kg dry matter (DM) to be determined from small (1-2 g DM) samples. This analytical method has been applied to the phthalate transfer study for agricultural recycling of sludges, where phthalate bioavailability has been studied in aquiculture using two types of experiments. Tomatoes have been grown in containers where the trace organics have been directly introduced as pure substances, and in a second experiment under the same growth conditions, sewage sludge has replaced the pure substances. Transfer of these trace organics has been followed into the various parts of the tomato plant and in general only the DEHP is worthy of note although its percentage transfer remains very low even in an experiment designed to maximize this.     

Development and application of a polar coating for stir bar sorptive extraction of emerging pollutants from environmental water samples

In the present study, a stir bar coated with hydrophilic polymer based on poly(N-vinylpyrrolidone-co-divinylbenzene) was prepared for the sorptive extraction of polar compounds. The main parameters affecting the polymerisation of the coating were investigated.The new stir bar was applied successfully in stir bar sorptive extraction with liquid desorption followed by liquid chromatography–mass spectrometry in tandem with a triple quadrupole for the determination of a group of polar pharmaceuticals and personal care products (PPCPs) in environmental water matrices. Different variables affecting extraction and desorption such as agitation speed, temperature, ionic strength and extraction time were optimised. The results showed that the stir bar is able to enrich the selected analytes effectively.The developed method was applied to determine a group of PPCPs in different complex environmental samples, including river, effluent and influent waste water.     

Integrated extraction and purification of total bioactive flavonoids from Toona sinensis leaves

An integrated procedure was developed to extract and purify total flavonoids from Toona sinensis leaves for the first time, in which pressurized liquid extraction was performed in tandem with HPD100 macroporous resin column. Consequently, the total flavonoids can be extracted using 10% EtOH, and the recovery and purity of total flavonoids was 71.05% and 66.60%. Moreover, products of high quality were obtained in an environmentally friendly process with lower consumption of time and solvent. The results demonstrated that the integrated extraction-adsorption procedure was an efficient process for the preparation of total bioactive flavonoids from Toona sinensis leaves.