Appraisal of “classic” and “novel” extraction procedure efficiencies for the isolation of polycyclic aromatic hydrocarbons and their derivatives from biotic matrices

Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) by Murraya paniculata (L.) Jack in South Kolkata, West Bengal, India: spatial and temporal variations

Attempts have been made in the present study for ascertaining the concentrations of atmospheric polycyclic aromatic hydrocarbons (PAHs) using passive biosamplers in preference to conventional air sampling methods. Mechanical stirring, sonication, Soxhlet technique and microwave-assisted Soxhlet extraction (MASE) were employed to extract PAHs from an evergreen plant (Murraya paniculata) leaves (having long life-span) sampled from polluted places of South Kolkata, India, with dense population and heavy traffic. Effects of extraction methods and operational parameters (solvent and time) on the recovery levels of PAHs were also investigated. Purified extracts, acquired through adsorption chromatography, were subjected to GC-MS and HPLC-UV analyses for qualitative and quantitative assessment of PAHs. Spatio-temporal distribution of accumulated PAHs across the sampling sites was monitored over premonsoon, postmonsoon and winter supported by pollutant source characterization. The results displayed that the extraction yields of Soxhlet (272.07 ± 26.15 μg g-1) and MASE (280.17 ± 15.46 μg g-1) were the highest among the four techniques. Conditions of extraction with toluene for 6 h were found to be most favorable for PAHs. In spatio-temporal analysis, total concentrations of PAHs in the foliar samples varied from 200.98 ± 2.72 to 550.79 ± 10.11 μg g-1 dry weight, and the highest values being recorded in the samples of Exide More because of daylong inexorable traffic flow/crowding increasing the burden of ambient PAHs. Widespread changes in meteorology exerted influence on seasonal concentrations of PAHs in plant leaves, and extent of leaf contamination by PAHs was observed extreme in winter followed by postmonsoon and then, premonsoon. Foliar accretion of PAHs differed in the study sites with diverse sources of emission from motor vehicles, fossil fuel and biomass burning along with other human interferences.

Pollution of water in Africa: a review of contaminants and fish as biomonitors and analytical methodologies-the case of Senegal

Environmental pollution is one of the major problems facing human health, ecosystems, and biodiversity. This is particularly the case for water quality in Senegal. Fish can be used as a biomonitor of pollution by accumulating pollutants from the environment through their tissues. Fish is an indispensable element in the assessment of the quality of the environment due to the diversity of biological cycles and their position in the food chain. Fish, which is very sensitive to chemical and bacterial pollution, concentrates pollutants and is a good indicator of water quality. This review presents water pollution in Senegal and the possibility of using fish as an ideal monitoring matrix for marine environments, to detect the concentration of heavy metals and organic pollutants. The different extraction and analytical techniques used for fish biomonitoring will be also described.

Solid-phase microextraction combined with gas chromatography/triple quadrupole tandem mass spectrometry for determination of nitrated polycyclic aromatic hydrocarbons in sediments

Nitro-polycyclic aromatic hydrocarbons have been detected in various environmental media. However, determination in sediment matrix is challenging due to the lack of a suitable method. In this study, a reliable method for determining 15 nitro-polycyclic aromatic hydrocarbons in sediments was developed based on accelerated solvent extraction and solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry. The accelerated solvent extraction and solid-phase microextraction are sample pre-treatment techniques that have advantages, such as rapid operation and minimal sample volume. Initially, the solid-phase microextraction was optimized using five commercial fibers and from that 65 μm polydimethylsiloxane/divinylbenzene fiber was selected as the best fiber. Further, the accelerated solvent extraction conditions were optimized by Taguchi experimental design, such as extraction temperature (120℃), extraction solvent (dichloromethane), number of cycles (two), static extraction period (4 min), and rinse volume (90%). The method parameters, such as limits of quantitation, and intraday and interday accuracy and precision, were in the range of 0.067-1.57 ng/g, 75.2-115.2%, 69.9-115.4%, and 1.0-16.5%, respectively. Upon meeting all the quality criteria, the method was applied successfully to analyze real sediment samples. Therefore, our study creates a new prospect for the future application of direct immersion solid-phase microextraction in sediment analysis.

Adsorption characteristics of polycyclic aromatic hydrocarbons from non-aqueous media using activated carbon derived from phenol formaldehyde resin: kinetics and thermodynamic study

Porous carbons were prepared by carbonization and activation of phenol formaldehyde resin by gasification with CO₂ at 900 °C. Prepared activated carbon from phenol formaldehyde was characterized by measuring thermogravimetry (TG), differential thermal analysis (DTA), pH, surface area, porosity, and pore size distribution. The specific surface area (SSA) of these carbons ranges from 562 to 1904 m²/g, while their point of zero charge (pHPZC) varies from 2.6 to 8.8. The ability of the prepared activated carbon by gasification with CO₂ at 900 °C from phenol formaldehyde resin (PFAC) to remove a series of polycyclic aromatic hydrocarbons (PAHs), e.g., naphthalene, fluorene, phenanthrene, pyrene, and fluoranthene, from mixtures of organic solvents with different polarities and chemical structures was tested. The adsorption capacity increases with the increasing the SSA and pHPZC of the carbons, confirming the roles of dispersive interactions. The kinetics and thermodynamics of the adsorption of phenanthrene as a model compound of PAH on PFAC in the organic solvent were studied. The adsorption capacity became notably greater with an increase in contact time and initial phenanthrene concentration.

A Critical Review about the Health Risk Assessment of PAHs and Their Metabolites in Foods

Polycyclic aromatic hydrocarbons (PAHs) are a family of toxicants that are ubiquitous in the environment. These contaminants generate considerable interest, because some of them are highly carcinogenic in laboratory animals and have been implicated in breast, lung, and colon cancers in humans. Dietary intake of PAHs constitutes a major source of exposure in humans. Factors affecting the accumulation of PAHs in the diet, their absorption following ingestion, and strategies to assess risk from exposure to these hydrocarbons following ingestion have received very little attention. This review, therefore, focuses on concentrations of PAHs in widely consumed dietary ingredients along with gastrointestinal absorption rates in humans. Metabolism and bioavailability of PAHs in animal models and the processes, which influence the disposition of these chemicals, are discussed. Finally, based on intake, disposition, and tumorigenesis data, the exposure risk to PAHs from diet is presented. This information is expected to provide a framework for refinements in risk assessment of PAHs.

Triacylglycerol Analysis in Human Milk and Other Mammalian Species: Small-Scale Sample Preparation, Characterization, and Statistical Classification Using HPLC-ELSD Profiles

In this work, a method for the separation of triacylglycerols (TAGs) present in human milk and from other mammalian species by reversed-phase high-performance liquid chromatography using a core-shell particle packed column with UV and evaporative light-scattering detectors is described. Under optimal conditions, a mobile phase containing acetonitrile/n-pentanol at 10 °C gave an excellent resolution among more than 50 TAG peaks. A small-scale method for fat extraction in these milks (particularly of interest for human milk samples) using minimal amounts of sample and reagents was also developed. The proposed extraction protocol and the traditional method were compared, giving similar results, with respect to the total fat and relative TAG contents. Finally, a statistical study based on linear discriminant analysis on the TAG composition of different types of milks (human, cow, sheep, and goat) was carried out to differentiate the samples according to their mammalian origin.

Analytical performance of two miniaturised extraction methods for triclosan and methyltriclosan, in fish roe and surimi samples

A new and reliable miniaturised QuEChERS-based extraction method combined with a dispersive SPE cleanup procedure for extracting triclosan and methyltriclosan from fish roe and surimi samples was proposed. The effectiveness of different extraction/partition conditions for QuEChERS method was systematically investigated, and the use of acetonitrile extraction solvent and MgSO4, PSA, C18 and Florisil as cleanup reagents was recommended in the final method. Other method based on ultrasonic extraction with ethylacetate and clean-up with SPE was also evaluated for these samples. Different polymeric and silica sorbents for clean up were tested and the combination of Florisil and PSA was finally selected. The performance of these miniaturised sample preparation methods combined with GC-MS with quadrupole detection were compared. Extraction efficiency as well as cleaning effectiveness, laboriousness and speed were taken as criteria for method evaluation. Satisfactory validation parameters, such as linearity, recovery, precision and LODs and LOQs for both developed analytical methods were obtained from fish roe and surimi samples. Finally, both methods were applied to real samples. The sensitivity of the proposed methods was good enough to ensure reliable determination of target analytes at concentration levels commonly found in this kind of samples.

Pressurised liquid extraction of volatile compounds in coffee bean

In this work, we reported a novel application of pressurised liquid extraction (PLE) on coffee bean. The condition of PLE was carefully optimised with the aid of response surface methodology (RSM) including adjustment of experimental parameters (solvent type and sample to hydromatrix ratio) and other operating parameters (i.e. temperature (50-100°C), pressure (1000-2000 psi) and static extraction time (5-15 min)). The coffee extracts obtained under three different extraction conditions were evaluated through descriptive sensory analysis. Then, the results showed that those targeted compounds obtained from PLE were nearly three times higher (1473 ppm) than conventional solvent extraction (571 ppm). Thus, PLE demonstrated the feasibility of producing a series of coffee extracts under controllable extraction conditions in correlation with desirable sensory attributes. This approach has not previously reported to characterise the aroma of coffee bean.

Optimization and validation of an extraction method for the analysis of polycyclic aromatic hydrocarbons in chocolate candies

Chocolate is a key ingredient in many foods such as milk shakes, candies, bars, cookies, and cereals. Chocolate candies are often consumed by mankind of all age groups. The presence of polycyclic aromatic hydrocarbons (PAHs) in chocolate candies may result in health risk to people. A rapid, precise, and economic extraction method was optimized and validated for the simultaneous determination of polycyclic aromatic hydrocarbons in chocolate candy by high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GS-MS) as a confirmatory technique. The method was optimized by using different solvents for liquid-liquid extraction, varying volume of de-emulsifying agent, and quantity of silica gel used for purification. The HPLC separation of 16 PAHs was carried out by C-18 column with mobile phase composed of acetonitrile : water (70 : 30) in isocratic mode with runtime of 20 min. Limit of detection, limit of quantification (LOQ), and correlation coefficients were found in the range of 0.3 to 4 ng g⁻¹, 0.9 to 12 ng g⁻¹, and 0.9109 to 0.9952, respectively. The exploration of 25 local chocolate candy samples for the presence of PAHs showed the mean content of benzo[a]pyrene as 1.62 ng g⁻¹, which representing the need to evaluate effective measures to prevent more severe PAHs contamination in chocolate candies in future.

PRACTICAL APPLICATION

Chocolate is one of the most favorite food items among people, especially children. Chocolate candies are often consumed by mankind of all age groups. Chocolate candies are often consumed by children in large quantities. The presence PAHs in chocolate candies may result in health risk to people. In the present study, a precise and cost effective rapid method was employed for the determination of PAHs, which can be employed for daily routine analysis of PAHs in chocolate products.

Evaluation of solid-phase microextraction conditions for the determination of polycyclic aromatic hydrocarbons in aquatic species using gas chromatography

This paper describes a headspace solid-phase microextraction (HS-SPME) procedure coupled to gas chromatography with mass spectrometric detection (GC-MS) for the determination of eight PAHs in aquatic species. The influence of various parameters on the PAH extraction efficiency was carefully examined. At 75 degrees C and for an extraction time of 60 min, a polydimethylsiloxane-divinylbenzene (PDMS/DVB) fiber coating was found to be most suitable. Under the optimized conditions, detection limits ranged from 8 to 450 pg g(-1), depending on the compound and the sample matrix. The repeatability varied between 7 and 15% (RSD). Accuracy was tested using the NIST SRM 1974b reference material. The method was successfully applied to different samples, and the studied PAHs were detected in several of the samples.

Sample preparation

A panorama of sample preparation methods has been composed from 481 references, with a highlight of some promising methods fast developed during recent years and a somewhat brief introduction on most of the well-developed methods. All the samples were commonly referred to molecular composition, being extendable to particles including cells but not to organs, tissues and larger bodies. Some criteria to evaluate or validate a sample preparation method were proposed for reference. Strategy for integration of several methods to prepare complicated protein samples for proteomic studies was illustrated and discussed.

Innovative method for determination of 19 polycyclic aromatic hydrocarbons in food and oil samples using gas chromatography coupled to tandem mass spectrometry based on an isotope dilution approach

An efficient and selective analytical method for the determination and the quantification of 19 polycyclic aromatic hydrocarbons (PAHs) in food and oil has been developed. This method includes the monitoring of 15 PAHs stated as a priority by the EU in their 2005/108 recommendation. The samples were extracted according to a selective extraction step using pressurized liquid extraction followed by a purification with polystyrene-divinylbenzene SPE. Identification and quantification were performed using GC-MS/MS, with an isotope dilution approach using (13)C-labelled PAHs. The novel combination of selective extraction followed by purification provides highly purified analytes combined to a fast and automated method. The advantages of GC-MS/MS as compared to other detection methods are tremendous in terms of sensitivity, selectivity and interpretation facilities. Limits of detection varied between 0.008 and 0.15 microg kg(-1), limits of quantification between 0.025 and 0.915 microg kg(-1) for PAHs in food. The calibration curves showed a good linearity for all PAHs (R(2)>0.99) and precision and recovery were fit for purpose. Trueness of the method was carried out using the US National Institute of Standards and Technology SRM 2977 reference material.

Sample handling strategies for the determination of persistent trace organic contaminants from biota samples

Even after emergence of most advanced instrumental techniques for the final separation, detection, identification and determination of analytes, sample handling continues to play a basic role in environmental analysis of complex matrices. In fact, sample preparation steps are often the bottleneck for combined time and efficiency in many overall analytical procedures. Thus, it is not surprising that, in the last two decades, a lot of effort has been devoted to the development of faster, safer, and more environment friendly techniques for sample extraction and extract clean up, prior to actual instrumental analysis. This article focuses on the state of the art in sample preparation of environmental solid biological samples dedicated to persistent organic pollutants (POPs) analysis. Extraction techniques such as Soxhlet extraction, sonication-assisted extraction, supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), pressurised liquid extraction (PLE) and matrix solid-phase dispersion (MSPD) are reviewed and their most recent applications to the determination of POPs in biota samples are provided. Additionally, classical as well as promising novel extraction/clean-up techniques such as solid phase microextraction (SPME) are also summarized. Finally, emerging trends in sample preparation able to integrate analytes extraction and their adequate clean-up are presented.

Induction of cytochrome P450 1A1 as a biomarker of Benzo-a-pyrene pollution in Egyptian fresh water fish

The activity of Ethoxyresorufin-o-dealkylase (EROD) in the liver of Oreochromis niloticus and Clarias gariepinus was evaluated as a response to experimental and natural contamination of water with Benzo-a-pyrene and/or cadmium. The activity was measured fluorimetrically in the hepatic S9 fraction while the content of the enzyme was measured by ELISA. The response appeared as early as six hours post exposure. This study also reveled that Oreochromis niloticus exhibits higher values of EROD activity than that of Clarias gariepinus. CYP450 1A1 content showed lower responsiveness when compared to EROD activity measurements. The present study also estimated the inhibitory effect of cadmium on CYP450 1A1 induction. The current results demonstrate that EROD activity reflects contamination of water with benzo-a-pyrene as a polycyclic aromatic hydrocarbon compound. Consequently it is a useful biomarker for monitoring this type of pollution.

Comparison of solid phase extraction, saponification and gel permeation chromatography for the clean-up of microwave-assisted biological extracts in the analysis of polycyclic aromatic hydrocarbons

The feasibility of different clean-up procedures was studied for the determination of polycyclic aromatic hydrocarbons (PAHs) in biota samples such as oysters, mussels and fish liver. In this sense, once the samples were extracted--essentially with acetone and in a microwave system--and before they could be analysed by gas chromatography-mass spectrometry (GC-MS), three different approaches were studied for the clean-up step: solid phase extraction (SPE), microwave-assisted saponification (MAS) and gel permeation chromatography (GPC). The main aim of this work was to maximise the recoveries of PAHs and to minimise the presence of interfering compounds in the last extract. In the case of SPE, Florisil cartridges of 1, 2 and 5 g, and silica cartridges of 5 g were studied. In that case, and with oysters and mussels, microwave-assisted extraction and 5 g Florisil cartridges provided good results. In addition, the concentrations obtained for Standard Reference Material (SRM) NIST 2977 (mussel tissue) were in good agreement with the certified values. In the case of microwave-assisted saponification, the extracts were not as clean as those obtained with 5 g Florisil and this fact lead to overestimate the concentration of the heaviest PAHs. Finally, the cleanest extracts were obtained by GPC. The method was successfully applied to mussels, oysters and hake liver, and the results obtained for NIST 2977 (mussel tissue) were within the confidence interval of the certified reference material for most of the certified analytes.

Influence of the extraction methodology on the analysis of polycyclic aromatic hydrocarbons in pasture vegetation

Pasture vegetation plays an important role in the air-surface exchange and food chain transfer of polycyclic aromatic hydrocarbons (PAHs). Therefore, considerable research has been focused towards measuring PAHs in vegetation using different analytical methods. However, in most cases information on the efficiencies of the different extraction methods employed is missing. This complicates data interpretation and inter-study comparisons. To address this deficiency, the extraction efficiencies of two commonly used pasture vegetation extraction techniques (sonication and soxhlet) and different solvents (hexane, DCM and hexane:acetone [4:1, v/v]) were compared. The completeness of the extraction was investigated using alkaline saponification in methanol. Soxhlet extraction was able to access between 60 and 90% of the total amount of PAHs in the pasture vegetation. Sonication was less efficient, only being able to extract between 10 and 50% of the PAHs. Extraction efficiencies were found to increase with increasing PAH molecular weight. The implications of these findings on data interpretation are discussed.

Pressurized liquid extraction in the analysis of food and biological samples

Originally, the use of the pressurized liquid extraction technique (PLE) was mainly focused on the extraction of environmental pollutants present in soil matrices, sediments, and sewage sludge. However, more recently the distinct advantages of this technique are being exploited in diverse areas, including biology, and the pharmaceutical and food industries. The aim of the present review is to explore recent analytical applications of this extraction technique (PLE) in the extraction of contaminant compounds and matrix components in food and biological samples, placing special emphasis on the strategies followed to obtain a rapid, selective, efficient and reliable extraction process.

Application of matrix solid-phase dispersion in the analysis of priority polycyclic aromatic hydrocarbons in fish samples

The performance of matrix solid-phase dispersion (MSPD) for the extraction of polycyclic aromatic hydrocarbons (PAHs) in fish tissue is described. The suitability of different solid supports was tested as well as the influence on the extraction efficiency of the natural fat content in samples. Under optimal conditions 0.6-0.8 g of tissue sample, are dispersed with 2 g of octadecylsiloxane (C18) and 0.5 g of anhydrous sodium sulphate and transferred to the top of a polyethylene solid-phase extraction cartridge which already contains 2 g of florisil and 1 g of C18. Cartridges were eluted with acetonitrile. The analysis of the extracts was carried out by high-performance liquid chromatography (HPLC) coupled with fluorescence detection. The proposed method provides detection limits between 0.04 and 0.32 ng/g for the different considered PAHs, below the maximum levels established by the some regulatory bodies for the six PAHs after recent oil spill episodes and European Union regulations. Recoveries over 80% were obtained for all compounds. Accuracy validation was carried out using the US National Institute of Standards and Technology (NIST) SRM 2977 reference material.