Determination of hydroxylated metabolites of polycyclic aromatic hydrocarbons in sediment samples by combining subcritical water extraction and dispersive liquid–liquid microextraction with derivatization

Unraveling the mechanisms of benzo[a]pyrene degradation by Pigmentiphaga kullae strain KIT-003 using a multi-omics approach

Polycyclic aromatic hydrocarbons (PAHs), notably benzo[a]pyrene (BaP), are environmental contaminants with multiple adverse ecological implications. Numerous studies have suggested the use of BaP biodegradation using various bacterial strains to remove BaP from the environment. This study investigates the BaP biodegradation capability of Pigmentiphaga kullae strain KIT-003, isolated from the Nak-dong River (South Korea) under specific environmental conditions. The optimum conditions of biodegradation were found to be pH 7.0, 35°C, and a salinity of 0 %. GC-MS analysis suggested alternative pathways by which KIT-003 produced catechol from BaP through several intermediate metabolites, including 4-formylchrysene-5-carboxylic acid, 5,6-dihydro-5,6-dihydroxychrysene-5-carboxylic acid (isomer: 3,4-dihydro-3,4-dihydroxychrysene-4-carboxylic acid), naphthalene-1,2-dicarboxylic acid, and 2-hydroxy-1-naphthoic acid. Proteomic profiles indicated upregulation of enzymes associated with aromatic compound degradation, such as nahAc and nahB, and of those integral to the tricarboxylic acid cycle, reflecting the strain's adaptability to and degradation of BaP. Lipidomic analysis of KIT-003 demonstrated that BaP exposure induced an accumulation of glycerolipids such as diacylglycerol and triacylglycerol, indicating their crucial role in bacterial adaptation mechanisms under BaP stress. This study provides significant scientific knowledge regarding the intricate mechanisms involved in BaP degradation by microorganisms.

A Review: Subcritical Water Extraction of Organic Pollutants from Environmental Matrices

Most organic pollutants are serious environmental concerns globally due to their resistance to biological, chemical, and photolytic degradation. The vast array of uses of organic compounds in daily life causes a massive annual release of these substances into the air, water, and soil. Typical examples of these substances include pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Since they are persistent and hazardous in the environment, as well as bio-accumulative, sensitive and efficient extraction and detection techniques are required to estimate the level of pollution and assess the ecological consequences. A wide variety of extraction methods, including pressurized liquid extraction, microwave-assisted extraction, supercritical fluid extraction, and subcritical water extraction, have been recently used for the extraction of organic pollutants from the environment. However, subcritical water has proven to be the most effective approach for the extraction of a wide range of organic pollutants from the environment. In this review article, we provide a brief overview of the subcritical water extraction technique and its application to the extraction of PAHs, PCBs, pesticides, pharmaceuticals, and others form environmental matrices. Furthermore, we briefly discuss the influence of key extraction parameters, such as extraction time, pressure, and temperature, on extraction efficiency and recovery.

Biomarkers for polycyclic aromatic hydrocarbons in human excreta: recent advances in analytical techniques-a review

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants that are generated by the incomplete combustion of organic materials. The main anthropogenic sources of PAHs are the combustion of solid fuels for heating purposes, illegal waste incineration, road transport and industries based on fossil fuels. PAHs can easily enter the body because they are present in all elements of the environment, including water, soil, air, and food. Due to their ubiquitous presence, PAHs, may exert a harmful effect on human health. Assessing PAH exposure through biomonitoring mostly involve techniques to measure the concentration of 1-hydroxypyrene in human urine. Nevertheless, through recent progress in analytical techniques, other common metabolites of PAHs in human biospecimens can be detected. A scientific literature search was conducted to determine which hydroxy derivatives of PAHs are markers of PAHs exposure and to reveal the leading sources of these compounds. Techniques for analyzing biological samples to identify OH-PAHs are also discussed. The most frequently determined OH-PAH in human urine is 1-hydroxypyrene, the concentration of which reaches up to a dozen ng/L in urine. Apart from this compound, the most frequently determined biomarkers were naphthalene and fluorene metabolites. The highest concentrations of 1- and 2-hydroxynaphthalene, as well as 2-hydroxyfluorene, are associated with occupational exposure and reach approximately 30 ng/L in urine. High molecular weight PAH metabolites have been identified in only a few studies. To date, PAH metabolites in feces have been analyzed only in animal models for PAH exposure. The most frequently used analytical method is HPLC-FLD. However, compared to liquid chromatography, the LOD for gas chromatography methods is at least one order of magnitude lower. The hydroxy derivatives naphthalene and fluorene may also serve as indicators of PAH exposure.

Miniaturized method for the quantification of persistent organic pollutants and their metabolites in HepG2 cells: assessment of their biotransformation

Biotransformation can greatly influence the accumulation and, subsequently, toxicity of substances in living beings. Although traditionally these studies to quantify metabolization of a compound have been carried out with in vivo species, currently, in vitro test methods with very different cell lines are being developed for their evaluation. However, this is still a very limited field due to multiple variables of a very diverse nature. So, an increasing number of analytical chemists are working with cells or other similar biological samples of very small size. This makes it necessary to address the development of analytical methods that allow determining their concentration both inside the cells and in their exposure medium. The aim of this study is to develop a set of analytical methodologies for the quantification of polycyclic aromatic hydrocarbons, PAHs (phenanthrene, PHE), and polybrominated diphenyl ethers, PBDEs (2,2',4,4'-tetrabromodiphenyl ether, BDE-47), and their major metabolites in cells and their exposure medium. Analytical methodologies, based on miniaturized ultrasound probe-assisted extraction, gas chromatography-mass spectrometry-microelectron capture detector (GC-MS-µECD), and liquid chromatography-fluorescence detector (LC-FL) determination techniques, have been optimized and then applied to a biotransformation study in HepG2 at 48 h of exposure. Significant concentrations of the major metabolites of PHE (1-OH, 2-OH, 3-OH, 4-OH-, and 9-OH-PHE) and BDE-47 (5-MeO-, 5-OH-, and 3-OH-BDE-47) were detected and quantified inside the cells and in the exposure medium. These results provide a new method for determination and improve information on the metabolization ratios for a better knowledge of the metabolic pathways and their toxicity.

Temporal-spatial variation, source forensics of PAHs and their derivatives in sediment from Songhua River, Northeastern China

The distribution patterns and health risk assessment of nitrated polycyclic aromatic hydrocarbons (NPAHs), hydroxy polycyclic aromatic hydrocarbons (OH-PAHs), and regular 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediment from the Songhua River in northeastern China were investigated in this research. During dry seasons, concentrations of 16 USEPA priority PAHs, OH-PAHs, and NPAHs were extremely high, with average values of 1220 ± 288, 317 ± 641, 2.54 ± 3.98, and 12.2 ± 22.1 ng/g (dry weight, dw). The dry period level was confirmed to be 4 times greater than the wet period concentration. Modeling with positive matrix factorization (PMF) and estimation of diagnostic isomeric ratios were applied for identifying sources, according to the positive matrix factorization model: vehicle emissions (38.1%), biomass burning (25%), petroleum source (23.4%), and diesel engines source (13.5%) in wet season as well as wood combustion (44.1%), vehicle source (40.2%), coke oven (10.8%), and biomass burning (4.9%) in the dry season. The greatest seasonal variability was attributed to high molecular weight compounds (HMW PAHs). BaP was confirmed to be 81% carcinogenic in this study, which offers convincing proof of the escalating health issues.

MOF-74/polystyrene-derived Ni-doped hierarchical porous carbon for structure-oriented extraction of polycyclic aromatic hydrocarbons and their metabolites from human biofluids

Polycyclic aromatic hydrocarbons (PAHs), as a major source that significantly increase the risk of developing lung cancer, severely jeopardize public health in modern society. The analysis of PAHs and their metabolites (hydroxylated PAHs, OH-PAHs) is important for biomonitoring and exposure assessment. However, due to the difference in their physico-chemical properties and matrix interference, realizing high-performance extraction of both PAHs and OH-PAHs is still a challenge. Herein, a nickel-doped hierarchical porous carbon (Ni/HPC) is synthesized by carbonizing the polystyrene (PS) infiltrated metal-organic frameworks (MOF-74(Ni)). The obtained Ni/HPC exhibits hierarchical pores and evenly distributed Ni atoms, providing efficient diffusion pathways and adsorption sites. The custom Ni/HPC-coated solid-phase microextraction (SPME) fiber shows superior enrichment capabilities for PAHs and their metabolites under various interfering conditions, verifying its practicability in real sample analysis. The proposed method provides a new strategy to synthesize carbon-based adsorbents that achieves matrix-resistant enrichment of PAHs and OH-PAHs, which simplifies the related sample preparation process for environmental analysis and clinical diagnosis.

A polymer-based dispersive solid phase extraction combined with deep eutectic solvent based-dispersive liquid-liquid microextraction for the determination of four hydroxylated polycyclic aromatic hydrocarbons from urine samples

A new and efficient extraction procedure was proposed and used for the simultaneous extraction of four hydroxylated metabolites polycyclic aromatic hydrocarbons from urine samples. The extraction procedure was started by dissolving an organic polymer into a water-miscible organic solvent (iso-propanol) and its injection into the sample solution. The sorbent was re-precipitated in all parts of the solution as tiny particles and the analytes were adsorbed onto the sorbent. After that, the sorbent was separated and the adsorbed analytes were eluted by choline chloride: dichloroacetic acid deep eutectic solvent. The elution solvent was mixed with choline chloride-3,3-dimethyl butyric acid deep eutectic solvent and the mixture was applied in dispersive liquid-liquid microextraction procedure for more concentration of the analytes. After optimization, the method validation was followed according to International Council Harmonization guidelines and the results showed that wide linear ranges (26-500 000 ng/L) and low limits of detection (3.6-7.2 ng/L) and quantification (11-26 ng/L) were obtained. Satisfactory enrichment factors (435-475) and extraction recoveries (87-95%), and acceptable relative standard deviations (equal or less than 8.6%) were obtained. Finally, the introduced method was successfully applied for determination of the analytes in urine samples obtained from tobacco smokers.

Facile fabrication of composited solid phase microextraction thin membranes for sensitive detections of trace hydroxylated polycyclic aromatic hydrocarbons in human urine

Solid phase microextraction (SPME) has potential to be used for the high-performance enrichments of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs), which are important biomarkers of PAH exposure. By choosing suitable adsorbent, it is conducive to fabricate new-type of SPME device for improved extraction efficiencies towards OH-PAHs. In this study, a novel method of surface solvent evaporation has been proposed to fabricate SPME thin membrane, integrating the advantages of polydimethylsiloxane (PDMS) and different porous adsorbents. The powdery metal organic framework (Uio66-NH₂), porous polymer (powdery polymer aerogel, PPA) and ordered mesoporous carbon (OMC) have been chosen as typical adsorbents and fabricated as thin membranes successfully, indicating the universality of the proposed method for membrane fabrication. Comparing the extraction efficiencies of three prepared membranes towards OH-PAHs, the OMC-PDMS membrane has demonstrated best enrichment efficiencies. The OMC-PDMS membrane was used for the enrichments of trace OH-PAHs in human urine of both smokers and nonsmokers, combining with liquid chromatographic tandem mass spectrometry (LC-MS/MS). The detection limits were in the range of 0.15-0.39 ng L^-1, and satisfactory recoveries were found to be 82.1%-115%. It can be seen that the universal strategy to fabricate SPME membrane is helpful to achieve broad-spectrum or selective enrichments of target analytes from complex matrix by simple modulation of membrane components.

Recovery of polycyclic aromatic hydrocarbons and their oxygenated derivatives in contaminated soils using aminopropyl silica solid phase extraction

The formation, fate, and toxicology of oxy-, hydroxy-, and carboxy- substituted PAH (OPAH, OHPAH, COOHPAH, respectively) alongside PAH in contaminated soils have received increasing attention over the past two decades; however, there are still to date no standardized methods available for their identification and quantitation in soil. Here we investigated and developed the first method using aminopropylsilica solid phase extraction (SPE) for these compounds. We further investigated the efficacy of the developed method for three soils representing a range of contamination levels and soil textural characteristics and evaluated the impact of different sample preparation steps on the recovery of targeted compounds. Average recovery of PAH, OPAH, and OHPAH standards were 99%, 84%, and 86%, respectively for the SPE method. In contrast, COOHPAH exhibited the lowest recovery (0-82%) and poor inter-batch reproducibility. Soil texture and contamination levels influenced full method efficiency. Specifically, soils with higher proportion of clay contributed to the loss of the higher molecular weight OHPAH prior to SPE. Soil with the highest contamination showed enhanced recovery of some lower-concentration mid weight PAH and OPAH, while the least contaminated soil showed greater sensitivity to evaporative losses during sample preparation. Recommendations for reducing matrix effects as well as the practice of using deuterated PAH surrogate standards for OPAH analysis are further discussed. Quantitation of recovered PAH and oxygenated PAH across the three soils showed high reproducibility (<10% relative standard deviation for a majority of compounds), supporting the use of this method for PAH, OPAH, and OHPAH at contaminated sites.

Pressurized liquid extraction followed by liquid chromatography coupled to a fluorescence detector and atmospheric pressure chemical ionization mass spectrometry for the determination of benzo(a)pyrene metabolites in liver tissue of an animal model of colon cancer

Since metabolism is implicated in the carcinogenesis of toxicants, an efficient extraction method together with an analytical method is warranted to quantify tissue burdens of a carcinogen and/or its metabolites. Therefore, the aim of this study was to validate a pressurized liquid extraction (PLE) method for measuring metabolites of benzo(a)pyrene [B(a)P; a food-borne carcinogen] from tissue samples. The sample extraction was performed separately by PLE and liquid-liquid extraction (LLE). PLE followed by high-performance liquid chromatography coupled to online fluorescence detector (HPLC-FLD) was used to quantify separated analytes; and by ultra-high-performance liquid chromatography (UHPLC) coupled to atmospheric pressure chemical ionization tandem mass spectrometry (UHPLC-APCI-MS/MS) were used for confirmation purposes. The UHPLC-MS/MS was set-up in the atmospheric pressure chemical ionization (APCI) positive interface with selective reaction monitoring (SRM). The analytical performance characteristics of the PLE technique was assessed at different temperatures, pressure, number of cycles and solvent types. A methanol + chloroform + water mixture (30:15:10, v/v/v) yielded greater recoveries at an extraction temperature range of 60-80°C, pressure of 10 MPa and an extraction time of 10 min. The PLE method was validated by the analysis of spiked tissue samples and measuring recoveries and limits of quantitation for the analytes of interest using HPLC-FLD equipment. The optimized PLE-HPLC-FLD method was used to quantify the concentrations of B(a)P metabolites in liver samples obtained from a colon cancer animal model. Overall, PLE performed better in terms of extraction efficiency, recovery of B(a)P metabolites and shortened sample preparation time when compared with the classic LLE method.

Critical review of micro-extraction techniques used in the determination of polycyclic aromatic hydrocarbons in biological, environmental and food samples

Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous environmental contaminants and their accurate determination is very important to human health and environment safety. In this review, sorptive-based micro-extraction techniques [such as Solid-Phase Micro-extraction (SPME), Stir Bar Sorptive Extraction (SBSE), Micro-extraction in Packed Sorbent (MEPS)] and solvent-based micro-extraction [Membrane-Mediated Liquid-Phase Micro-extraction (MM-LPME), Dispersive Liquid-Liquid Micro-extraction (DLLME), and Single Drop Micro-extraction (SDME)] developed for quantification of PAHs in environmental, biological and food samples are reviewed. Moreover, recent micro-extraction techniques that have been coupled with other sample extraction strategies are also briefly discussed. The main objectives of these micro-extraction techniques are to perform extraction, pre-concentration and clean up together as one step, and the reduction of the analysis time, cost and solvent following the green chemistry guidelines.

Comprehensive database of Manufactured Gas Plant tars. Part B. Aliphatic and aromatic compounds

RATIONALE

Coal tars are a mixture of organic and inorganic compounds that were produced as a by-product from the manufactured gas and coke making industries. The composition of the tar produced varies depending on many factors; these include the temperature of production and the type of retort used. As different production processes produce different tars, a comprehensive database of the compounds present within coal tars from different production processes is a valuable resource. Such a database would help to understand how their chemical properties differ and what hazards the compounds present within these tars might pose. This study focuses on the aliphatic and aromatic compounds present in a database of 16 different tars from five different production processes.

METHODS

Samples of coal tar were extracted using accelerated solvent extraction (ASE) and derivatised post-extraction using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS). The derivatised samples were analysed using two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GCxGC/TOFMS).

RESULTS

A total of 198 individual aliphatic and 951 individual aromatic compounds were detected within 16 tar samples produced by five different production processes. The polycyclic aromatic hydrocarbon (PAH) content of coal tars varies greatly depending on the production process used to obtain the tars and this is clearly demonstrated within the results. The aliphatic composition of the tars provided an important piece of analytical information that would have otherwise been missed with the detection of petrogenic compounds such as alkyl cyclohexanes.

CONCLUSIONS

The aromatic compositions of the tar samples varied greatly between the different production processes investigated and useful analytical information was obtained about the individual production process groups. Alkyl cyclohexanes were detected in all samples from sites known to operate Carbureted Water Gas plants and not detected in those that did not. This suggests that petrogenic material may be expected at many UK gaswork sites.

Comprehensive composition of Creosote using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS)

Creosote is a distillation product of coal tar and is widely used as wood preservative for railway sleepers, utility poles and for other applications. Creosote can have potentially negative effects on the environment and many of the components are toxic. This study presents the analysis of a Creosote sample from a former wood impregnation plant located in the UK. The sample was analysed using two dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) and a database of compounds that could be detected was produced. The GCxGG-TOFMS was capable of detecting 1505 individual compounds, which is far more than previous estimates for the number of compounds present within Creosote. Post extraction derivatization using BTSFA with 1% TMCS was employed to increase the potential number of compounds detected with 255 derivatized compounds detected, 231 of which would not have been detected without prior derivatization. Selected derivatized compounds were quantified with limits of detection ranging from 0.6 mg/kg to 1.6 mg/kg from a concentrated dense non-aqueous phase liquid (DNAPL). This work presents the first published full analysis of a Creosote using GCxGC-TOFMS combined with derivatization.

Development of a subcritical water extraction approach for trace analysis of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in poultry tissues

Subcritical water extraction was investigated as a novel and alternative technology for the separation of trace amounts of chloramphenicol, thiamphenicol, florfenicol and its major metabolite florfenicol amine from poultry tissues and its results were compared with those of conventional shaking extraction, ultrasonic extraction, and pressurized liquid extraction. Decreasing the polarity of water by successively increasing the extraction temperature from 50°C to 200°C at the moderate pressure enabled selective, highly effective extractions to be performed. Rapid quantification of the target compounds was carried out by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). The critical parameters of subcritical water extraction such as solvent modifier, temperature, pressure, extraction time, and static cycles were varied with control. The optimized extraction procedures using subcritical water as extraction solvent, were carried out on a pressurized liquid extractor operated at 150°C and 100bar, applying two static cycles for 3min. Average recoveries of the four analytes from fortified samples ranged between 86.8% and 101.5%, with relative standard deviations (RSDs) lower than 7.7%. The limits of detection (LODs) and quantification (LOQs) for the target compounds were in the ranges of 0.03-0.5μgkg(-1) and 0.1-2.0μgkg(-1), respectively. The proposed method is fast, sensitive, water-based thus more environmental acceptable, making it a suitable replacement for conventional organic solvent extraction in veterinary drug residue analysis.

Characterizing the parent and oxygenated polycyclic aromatic hydrocarbons in mangrove sediments of Hong Kong

Parent and oxygenated polycyclic aromatic hydrocarbons (PAHs) were investigated in mangrove sediments of Hong Kong. Most of the analytes were detected, and the dominant carbonylic and hydroxylated PAHs in mangrove sediments were 9-fluorenone and 2-hydroxy fluorene, respectively. The concentration of 9-fluorenone and 9,10-anthraquinone was higher than their parent PAHs. Moreover, the concentration of total organic matter (TOM) related with those of the parent PAHs and carbonylic PAHs, except for hydroxylated PAHs, which indicated that TOM was not the only factor regulating the distribution of oxygenated PAHs. Nevertheless, the parent PAHs in mangrove sediments was correlated positively with carbonylic PAHs which demostrated not only the similar source but also the fate of these two compound class. However, hydroxylated PAHs had different source by comparing with parent PAHs and carbonylic PAHs, they were probably originated from biodegradation and accumulated in mangrove sediments.

Optimization of an accelerated solvent extraction dispersive liquid-liquid microextraction method for the separation and determination of essential oil from Ligusticum chuanxiong Hort by gas chromatography with mass spectrometry

In this study, an accelerated solvent extraction dispersive liquid-liquid microextraction coupled with gas chromatography and mass spectrometry was established and employed for the extraction, concentration and analysis of essential oil constituents from Ligusticum chuanxiong Hort. Response surface methodology was performed to optimize the key parameters in accelerated solvent extraction on the extraction efficiency, and key parameters in dispersive liquid-liquid microextraction were discussed as well. Two representative constituents in Ligusticum chuanxiong Hort, (Z)-ligustilide and n-butylphthalide, were quantitatively analyzed. It was shown that the qualitative result of the accelerated solvent extraction dispersive liquid-liquid microextraction approach was in good agreement with that of hydro-distillation, whereas the proposed approach took far less extraction time (30 min), consumed less plant material (usually <1 g, 0.01 g for this study) and solvent (<20 mL) than the conventional system. To sum up, the proposed method could be recommended as a new approach in the extraction and analysis of essential oil.

Determination of Urinary PAH Metabolites Using DLLME Hyphenated to Injector Port Silylation and GC-MS-MS

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants and well-known carcinogens. Hydroxy derivatives of PAH are considered as biomarkers of PAH exposure, and there is a need to measure these metabolites at low concentrations. So, a precise and eco-friendly analytical method has been developed for rapid determination of PAH metabolites. For the first time, a new analytical method based on coupling of dispersive liquid-liquid microextraction (DLLME) with auto-injector port silylation (auto-IPS) followed by gas chromatography-tandem mass spectrometry (GC-MS-MS) analysis is reported for the analysis of seven urinary PAH metabolites. Factors affecting DLLME and IPS, such as type and volume of extraction and disperser solvent, pH, ionic strength, injector port temperature, volume of N,O-bis(trimethylsilyl)trifluoroacetamide and type of solvent were investigated. Under optimized conditions, the limit of detection and limit of quantification were found to be in the range of 1-9 and 3-29 ng/mL, respectively. Satisfactory recoveries of metabolites in urine samples in the range of 87-95% were found. The developed method has been successfully applied for the determination of PAH metabolites in urine samples of exposed workers. DLLME-auto-IPS-GC-MS-MS method is time, labor, solvent and reagent saving, which can be routinely used for the analysis of urinary PAH metabolites.

Characterizing the parent and alkyl polycyclic aromatic hydrocarbons in the Pearl River Estuary, Daya Bay and northern South China Sea: influence of riverine input

Distributions of 31 parent polycyclic aromatic hydrocarbons (PAHs) and 29 alkyl PAHs in surface sediments of the Pearl River Estuary (PRE), Daya Bay (DYB) and northern South China Sea (SCS) were examined to study the influence of riverine input. It was found that the contributions of riverine input to sediment PAHs in PRE was much higher than other areas. However, higher proportion of alkyl PAHs and low molecular weight PAHs in DYB and the northern SCS was observed, indicating their different sources. Nevertheless, the sediment PAHs in PRE were heterogeneous and affected by the hydrodynamic conditions. The high molecular weight PAHs were dominant in PRE and enriched in the depositional area of suspended particular matter (SPM). Moreover, the concentration of PAHs in SPM was similar to those in surface sediments and dominated in water columns. Therefore, SPM played a very important role in transportation and distribution of PAHs in PRE.

Determination of 13 endocrine disrupting chemicals in sediments by gas chromatography-mass spectrometry using subcritical water extraction coupled with dispersed liquid-liquid microextraction and derivatization

In this study, a sample pretreatment method was developed for the determination of 13 endocrine disrupting chemicals (EDCs) in sediment samples based on the combination of subcritical water extraction (SWE) and dispersed liquid-liquid microextraction (DLLME). The subcritical water that provided by accelerated solvent extractor (ASE) was the sample solution (water) for the following DLLME and the soluble organic modifier that spiked in the subcritical water was also used as the disperser solvent for DLLME in succession. Thus, several important parameters that affected both SWE and DLLME were investigated, such as the extraction solvent for DLLME (chlorobenzene), extraction time for DLLME (30s), selection of organic modifier for SWE (acetone), volume of organic modifier (10%) and extraction temperature for SWE (150 °C). In addition, good chromatographic behavior was achieved for GC-MS after derivatisation by using N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA). As a result, proposed method sensitive and reliable with the limits of detection (LODs) ranging from 0.006 ng g(-1) (BPA) to 0.639 ng g(-1) (19-norethisterone) and the relative standard deviations (RSDs) between 1.5% (E2) and 15.0% (DES). Moreover, the proposed method was compared with direct ASE extraction that reported previously, and the results showed that SWE-DLLME was more promising with recoveries ranging from 42.3% (dienestrol) to 131.3% (4,5α-dihydrotestosterone), except for diethylstilbestrol (15.0%) and nonylphenols (29.8%). The proposed method was then successfully applied to determine 13 EDCs sediment of Humen outlet of the Pearl River, 12 of target compounds could be detected, and 10 could be quantitative analysis with the total concentration being 39.6 ng g(-1), and which indicated that the sediment of Humen outlet was heavily contaminated by EDCs.

Applications of liquid-phase microextraction in the sample preparation of environmental solid samples

Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

Longer-term and short-term variability in pollution of fluvial sediments by dioxin-like and endocrine disruptive compounds

Changes in pollutant loads in relatively dynamic river sediments, which contain very complex mixtures of compounds, can play a crucial role in the fate and effects of pollutants in fluvial ecosystems. The contamination of sediments by bioactive substances can be sensitively assessed by in vitro bioassays. This is the first study that characterizes detailed short- and long-term changes in concentrations of contaminants with several modes of action in river sediments. One-year long monthly study described seasonal and spatial variability of contamination of sediments in a representative industrialized area by dioxin-like and endocrine disruptive chemicals. There were significant seasonal changes in both antiandrogenic and androgenic as well as dioxin-like potential of river sediments, while there were no general seasonal trends in estrogenicity. Aryl hydrocarbon receptor-dependent potency (dioxin-like potency) expressed as biological TCDD-equivalents (BIOTEQ) was in the range of 0.5-17.7 ng/g, dry mass (dm). The greatest BIOTEQ levels in sediments were observed during winter, particularly at locations downstream of the industrial area. Estrogenicity expressed as estradiol equivalents (EEQ) was in the range of 0.02-3.8 ng/g, dm. Antiandrogenicity was detected in all samples, while androgenic potency in the range of 0.7-16.8 ng/g, dm dihydrotestosterone equivalents (DHT-EQ) was found in only 30 % of samples, most often during autumn, when antiandrogenicity was the least. PAHs were predominant contaminants among analyzed pollutants, responsible, on average, for 13-21 % of BIOTEQ. Longer-term changes in concentrations of BIOTEQ corresponded to seasonal fluctuations, whereas for EEQ, the inter-annual changes at some locations were greater than seasonal variability during 1 year. The inter- as well as intra-annual variability in concentrations of both BIOTEQ and EEQ at individual sites was greater in spring than in autumn which was related to hydrological conditions in the river. This study stresses the importance of river hydrology and its seasonal variations in the design of effective sampling campaigns, as well as in the interpretation of any monitoring results.

Ultrasound assisted dispersive liquid–liquid microextraction followed by injector port silylation: a novel method for rapid determination of quinine in urine by GC–MS

Background: Silylation is a widely used derivatization method for the analysis of polar analytes by GC–MS. Ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) is an ecofriendly, rapid and simple microextraction method. For the first time, a novel approach has been developed and applied for the analysis of quinine in urine by combining UA-DLLME with injection port silylation. Results: The LOD and LOQ were found to be 5.4 and 18 ng/ml. The intra- and inter-day precisions were less than 5 and 8%, respectively. Mean recoveries of quinine were found to be in the range of 87 to 96%. Conclusion: Ultrasound-assisted dispersive liquid–liquid microextraction is rapid, simple and consumes less reagent for the analysis of polar analytes such as quinine.