Accelerated solvent extraction and gas chromatography/mass spectrometry for determination of polycyclic aromatic hydrocarbons in smoked food samples

Occurrence, distribution and sources of petroleum contamination in reef-associated sediments of the Gulf of Mannar, India

The distribution of saturated hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) was assessed in superficial sediment samples collected from Mandapam island groups, Gulf of Mannar, India. The hydrocarbon distribution pattern and the n-alkane indices (e.g., carbon preference index (CPI) and natural n-alkanes ratio (NAR)) were deployed to differentiate between the biogenic and anthropogenic sources. Petroleum pollution was indicated by the pristane/phytane ratio close to 1. Presence of a prominent unresolved complex mixture (UCM) as well as hopane concentrations further supported this assertion. The evaluation of petrogenic sources of contamination were also comprehended by various diagnostic ratios of PAHs. The sites associated with shipping activities, tourism, and located near the mainland and accessible portions of the islands exhibited high petroleum contamination. Correlation analysis underlines the significance of combining petroleum-specific marker compounds and diagnostic ratios to improve the assessment of human influence on marine ecosystems.

Optimization of the Efficient Extraction of Organic Components in Atmospheric Particulate Matter by Accelerated Solvent Extraction Technique and Its Application

Organic components in atmospheric fine particulate matter have attracted much attention and several scientific studies have been performed, although most of the sample extraction methods are time consuming and laborious. Accelerated solvent extraction (ASE) is a new sample extraction method offering number of advantages, such as low extraction cost, reduced solvent and time consumption, and simplified extraction protocols. In order to optimize ASE methods to determine the concentrations of organic compounds in atmospheric fine particulate matter, different parameters were set out for the experiment, and the optimal method was selected according to the recoveries of the standard (i.e., n−alkanes and polycyclic aromatic hydrocarbons (PAHs)). This study also involves a comparison of the optimal method with the traditional method of ultrasonic extraction (USE). In addition, the optimized method was applied to measure the mass concentrations of organic compounds (n−alkanes and PAHs) in fine particulate matter samples collected in Beijing. The findings showed that the average recovery of target compounds using ASE was 96%, with the majority of compounds falling within the confidence levels, and the ASE recoveries and precision were consistent with the USE method tested. Furthermore, ASE combines the advantages of high extraction efficiency, automation, and reduced solvent use. In conclusion, the optimal ASE methods can be used to extract organic components in atmospheric particulate matter and serve as a point of reference for the development of analytical methodologies for assessing organic compounds in atmospheric particulate matter in China.

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.

Levels and risk assessment of polycyclic aromatic hydrocarbons in wood vinegars from pyrolysis of biomass

A method quantifying 16 polycyclic aromatic hydrocarbons (PAHs) in wood vinegars (WVs) obtained from slow pyrolysis of biomass with ultrasonic-assisted liquid-liquid extraction/gas chromatography-mass spectrometry (USALLE/GC-MS) was established. The recovery range was 83-128%, and the relative standard deviations (RSD%) were less than 15% except naphthalene, acenaphthylene and acenaphthene. Acenaphthylene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, and pyrene were observed in all samples and the other 9 compounds, including benzopyrene (B[a]P), were not detected. The concentration of ∑PAHs referred to the sum total of 7 PAHs mentioned above was 22.0-498.3 μg L^-1. The PAHs concentration increased with the increasing pyrolysis temperature in bamboo willow WV, pinus sylvestris WV, and corncob WV, while it increased initially, and then decreased with a maximum at 550 °C in rice husk WV. The ∑PAHs concentration increased with a higher heating rate in the white pine WV, while rice husk WV and cornstalk WV showed the opposite trend. The varied condensed aromatic ring number showed that 3-ring PAHs relatively were the main component in all kind WVs. 3-ring PAHs increased with increasing temperatures, while 4-ring PAHs showed an opposite trend in sawdust WV and corncob WVs. A higher cellulose content in sawdust enhanced the reaction of lignin leading to a higher concentration of PAHs than that in straws and leaves. Calculations of the toxicity equivalents of PAHs in WVs indicated that anthracene was the most toxic among the PAHs, and the pinus sylvestris WV had the highest risk of ∑PAHs toxicity in all WVs.

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.

Polycyclic aromatic hydrocarbons in seasoned-roasted laver and their reduction according to the mixing ratio of seasoning oil and heat treatment in a model system

In food processing, polycyclic aromatic hydrocarbons (PAHs) can be generated during heat treatment, and the PAHs in seasoned-roasted (SR) laver can be reduced by checking points during manufacturing. Benzo (a) anthracene, chrysene, benzo (b) fluoranthene, and benzo (a) pyrene have been identified in SR laver via GC/MS. We confirmed that in practice, the PAHs in SR laver form from the mixed oil (57%) and roasting process (43%). To mitigate the formation of PAHs, we used a model system to change the mixing ratio of oil, roasting temperature, and time. A significant reduction (35%) was observed in the PAH level as the perilla oil was removed from the mixed oil composition and roasting continued at 350 °C for 10 s. These results show that the composition of the mixing oil and the parameters of the heat treatment are crucial factors that contribute to the formation of PAHs in roasted laver.

Bioaccumulation of Polycyclic Aromatic Hydrocarbons for Forensic Assessment Using Gas Chromatography-Mass Spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are considered xenobiotics of a potentially carcinogenic nature, being accumulated in the fatty tissue of the body. The objective of this work was the development and validation of a new analytical method to check the bioaccumulation of these toxic compounds in human organs obtained from autopsies. The contaminants were first isolated from the tissues by salt-assisted liquid-liquid extraction in acetonitrile. Because of the low concentrations of these compounds in the human body, a dispersive liquid-liquid microextraction procedure was included. The preconcentrated samples were analyzed by gas chromatography-mass spectrometry to identify the compounds. Principal component analysis was applied to show the natural clustering of forensic samples and orthogonal partial least-squares discriminant analysis to develop a multivariate regression method, which permitted the classification of samples. The quantification limits for the 13 PAHs (acenaphthylene, fluorene, phenanthrene, anthracene, pyrene, benzo(a)anthracene, chrysene, 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) analyzed were in the 0.06-0.44 ng g^-1 range, depending on the compound, while the mean intraday relative standard deviation of about 7% demonstrated the high precision of the method. Linearity was verified in the 0.5-200 ng g^-1 range, and the enrichment factors were between 55 and 122. The results provided by the analysis of seven different human organs (brain, liver, kidney, lung, heart, spleen, and abdominal fat) from eight autopsies confirmed the PAH-bioaccumulation capacity of human body, fat showing the highest degree of bioaccumulation. The present work is the first study on PAH contamination in different organs obtained from autopsies, being PAH detected in most human samples at values ranged from 0 to 19 ng g^-1.

Aroma Profile Characterization of Mahi-Mahi and Tuna for Determining Spoilage Using Purge and Trap Gas Chromatography-Mass Spectrometry

Alcohols, aldehydes, ketones, amines, and sulfur compounds are essential aroma compounds related to fish flavor and spoilage. Gas chromatography-mass spectrometry (GC-MS) is an instrument that is widely used to identify and quantify volatile and semi-volatile compounds in fish products. In this research, a simple and accurate GC-MS method was developed to determine the aroma profile of mahi-mahi and tuna for chemical indicators of spoilage. In the developed GC-MS method, trichloroacetic acid (TCA) solution was used to extract analytes from homogenized fish samples. The purge and trap system was used for sample introduction, and the GC-MS with an RTX-Volatile Amine column was able to separate compounds without a derivatization procedure. The created purge and trap gas chromatography-mass spectrometry (PT-GC-MS) method could identify and quantify twenty aroma compounds in mahi-mahi (Coryphaena hippurus) and 16 volatile compounds in yellowfin tuna (Thunnus albacares) associated with fish spoilage. The amines (dimethylamine, trimethylamine, isobutylamine, 3-methylbutylamine, and 2-methylbutanamine), alcohols (2-ethylhexanol, 1-penten-3-ol and isoamyl alcohol, ethanol), aldehydes (2-methylbutanal, 3-methylbutanal, benzaldehyde), ketones (acetone, 2,3-butanedione, 2-butanone, acetoin), and dimethyl disulfide strongly statistically correlated with poorer quality tuna and mahi-mahi and were considered as the key spoilage indicators. PRACTICAL APPLICATION: A simplified and rapid purge and trap gas chromatography-mass spectrometry (PT-GC-MS) method developed in this research was able to identify and quantify important spoilage compounds in mahi-mahi and yellowfin tuna. This method is an efficient analytical method for determining volatile profiles of fish samples for industry analytical labs or the government. The identified analytical quality markers can be used to monitor the spoilage level of tuna and mahi-mahi.

Characterization and ecological risk of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in sediments of Shadegan international wetland, the Persian Gulf

The distribution and sources of PAHs and n-alkanes were determined in the surface sediments from 202 locations in Shadegan international wetland with 537,700ha. The concentrations of total n-alkanes and PAHs ranged from 395.3 to 14933.46μgg^-1dw and 593.74 to 53393.86ngg^-1dw, respectively. Compared with other worldwide surveys, the concentration and contamination of sedimentary hydrocarbons were classified very high. A common petrogenic hydrocarbon source was strongly suggested in all sites by n-alkanes' profile with a Cmax at n-C₂₀, Pr/Ph and CPI ratios<1 in all sites, and high percentage of UCM. Typical profile of petrogenic PAHs with alkyl-substituted naphthalenes and phenanthrenes predominance, various PAH ratios and multivariate analysis indicated that PAHs were mainly derived from petrogenic source. Naphthalene-derived compounds in all sites were significantly above their ERL, and adversely affected benthic biota. 92% of the sites had mean ERM values<0.1, indicating high ecological risk on the wildlife of the wetland.

The Occurrence of 16 EPA PAHs in Food - A Review

Occurrence and toxicity of polycyclic aromatic hydrocarbons (PAHs) have been extensively studied in countries all over the world. PAHs generally occur in complex mixtures which may consist of hundreds of compounds. The U.S. Environmental Protection Agency (EPA) proposed in the 1970 to monitor a set of 16 PAHs which are frequently found in environmental samples. This article reviews the suitability of the 16 EPA PAHs for the assessment of potential health threats to humans stemming from the exposure to PAHs by food ingestion. It presents details on analysis methods, the occurrence of PAHs in food, regulatory aspects, and related risk management approaches. In addition, consideration is given to newer evaluations of the toxicity of PAHs and the requirements for risk assessment and management stemming from them.

Quantitation of polycyclic aromatic hydrocarbons (PAH4) in cocoa and chocolate samples by an HPLC-FD method

As a consequence of the PAH4 (sum of four different polycyclic aromatic hydrocarbons, named benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) maximum levels permitted in cocoa beans and derived products as of 2013, an high-performance liquid chromatography with fluorescence detection method (HPLC-FD) was developed and adapted to the complex cocoa butter matrix to enable a simultaneous determination of PAH4. The resulting analysis method was subsequently successfully validated. This method meets the requirements of Regulation (EU) No. 836/2011 regarding analysis methods criteria for determining PAH4 and is hence most suitable for monitoring the observance of the maximum levels applicable under Regulation (EU) No. 835/2011. Within the scope of this work, a total of 218 samples of raw cocoa, cocoa masses, and cocoa butter from several sample years (1999-2012), of various origins and treatments, as well as cocoa and chocolate products were analyzed for the occurrence of PAH4. In summary, it is noted that the current PAH contamination level of cocoa products can be deemed very slight overall.

Determination of light-medium-heavy polycyclic aromatic hydrocarbons in vegetable oils by solid-phase extraction and high-performance liquid chromatography with diode array and fluorescence detection

A new method for determination of 16 polycyclic aromatic hydrocarbons (PAHs)-naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, 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-in vegetable oils was developed. Solid-phase extraction (SPE) prior to high-performance liquid chromatography with fluorescence detection could be used for all those PAHs except acenaphthylene. Acenaphthylene could be detected using a diode array detector at 228 nm. The parameters and variables that affect the extraction were investigated. Under optimum conditions: the extract reagent was centrifuged at 4 °C and evaporated. After that a SPE procedure was used for further cleanup. The limits of detection and limits of quantification were in the range of 0.01-2.35 and 0.04-7.00 μg kg(-1) in vegetable oil, respectively. The relative standard deviations were under 5%.

Overview on polycyclic aromatic hydrocarbons: occurrence, legislation and innovative determination in foods

Polycyclic aromatic hydrocarbons are ubiquitous compounds, well-known to be carcinogenic, which can reach the food in different ways. Thus the analysis of such compounds has always been of great importance. The aim of the present review, is not only to give an overview of the most recent sample preparation and analytical approaches (such as pressurized liquid extraction, solid-phase microextraction, supercritical fluid extraction, etc.), but also to introduce such a topic to researchers who want to approach it for the first time; therefore, the most significant references related to general aspects, such as formation, toxicity, risk assessment, occurrence in food, are reported and briefly discussed.

Response surface modeling and optimization of accelerated solvent extraction of four lignans from fructus schisandrae

A new method based on accelerated solvent extraction (ASE) combined with response surface methodology (RSM) modeling and optimization has been developed for the extraction of four lignans in Fructus Schisandrae (the fruits of Schisandra chinensis Baill). The RSM method, based on a three level and three variable Box-Behnken design (BBD), was employed to obtain the optimal combination of extraction condition. In brief, the lignans schizandrin, schisandrol B, deoxyschizandrin and schisandrin B were optimally extracted with 87% ethanol as extraction solvent, extraction temperature of 160 °C, static extraction time of 10 min, extraction pressure of 1,500 psi, flush volume of 60% and one extraction cycle. The 3D response surface plot and the contour plot derived from the mathematical models were applied to determine the optimal conditions. Under the above conditions, the experimental value of four lignans was 14.72 mg/g, which is in close agreement with the value predicted by the model.

Genotoxic and enzymatic effects of fluoranthene in microsomes and freshly isolated hepatocytes from sole (Solea solea)

The fluoranthene (Fluo) is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) in human food and in marine compartments. However, the existing data on its genotoxicity is poor and controversial. The aim of this study was to assess in vitro the potential genotoxicity of Fluo in sole and its possible effect on CYP450 modulation. Freshly isolated hepatocytes were exposed for 24 h to a range of Fluo concentrations from 0.5 to 50 μM in both culture flasks and microplate wells. The ethoxyresorufin-O-deethylase (EROD) activity was measured as an indicator of the activity of the cytochrome P450 1A1 (CYP1A1). The genotoxic effects were evaluated by measuring both DNA strand breaks and DNA adducts by the alkaline comet assay and the postlabeling technique respectively. Calf thymus DNA was also exposed to Fluo in the presence of sole liver microsomes in order to check for Fluo DNA adduct formation. In sole hepatocytes, Fluo was shown to induce a decrease in the EROD activity in a concentration-dependent manner. A significant genotoxic effect was observed in terms of DNA strand breakage from an exposure concentration of 5 μM: despite a concentration-dependent effect was observed, it did not follow a linear dose-response. The response was similar whatever the way of exposure in flasks or in wells. One reproducible adduct was detected in the hepatocytes exposed to the highest concentrations of Fluo. The formation of Fluo adducts was confirmed by the detection of one reproducible adduct following in vitro exposure of calf thymus DNA to 100 and 200 μM of Fluo in the presence of sole microsomes. These results demonstrate the potential of sole hepatocytes to metabolize Fluo in 24 h into reactive species, able to induce genotoxicity by DNA strand breakage and DNA adduct formation. Moreover, a miniaturized cell exposure system was validated for further experiments using fewer amounts of hepatocytes and contaminants, and allowing exposure to PAH metabolites.

Determination of parent and substituted polycyclic aromatic hydrocarbons in high-fat salmon using a modified QuEChERS extraction, dispersive SPE and GC-MS

A fast and easy modified QuEChERS (quick, easy, cheap, rugged and safe) extraction method has been developed and validated for determination of 33 parent and substituted polycyclic aromatic hydrocarbons (PAHs) in high-fat smoked salmon that greatly enhances analyte recovery compared to traditional QuEChERS procedures. Sample processing includes extraction of PAHs into a solution of ethyl acetate, acetone and isooctane followed by cleanup with dispersive SPE and analysis by GC-MS in SIM mode. Method performance was assessed in spike recovery experiments (500 μg/g wet weight) in three commercially available smoked salmon with 3-11% fat. Recoveries of some 2-, 3- and 5-ring PAHs were improved 50-200% over traditional methods, while average recovery across all PAHs was improved 67%. Method precision was good with replicate extractions typically yielding relative standard deviations <10%, and detection limits were in the low ng/g range. With this method, a single analyst could extract and clean up ≥60 samples for PAH analysis in an 8 h work day.

Spatial distribution and health risk of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in the water of the Luanhe River Basin, China

The objectives of this study were to investigate the contamination levels and dispersion patterns of heavy metals and polycyclic aromatic hydrocarbons (PAHs) and to estimate the risk to health effects within the Luanhe river basin of northern Hebei Province, China. Samples of water were collected from upstream to downstream locations, and also from the main tributaries of Luanhe river. After appropriate preparation, all samples were analyzed for eight metals (As, Hg, Cd, Cr, Pb, Cu, Zn, and Fe) and 16 PAHs. Mean concentrations of As, Cd, Cu, and Zn were within the permissible levels, but Hg, Pb, and Fe concentrations were exceeded at some sites. The results indicated that the metal levels of upriver sites were higher than lower river sites; the metal levels of the main river were higher than ones of the tributaries except for Goutaizi at Xiaoluanhe. Only seven out 16 PAH components, which were mostly three- to four-ring compounds, were detected. Predominance of three- to four-ring PAHs suggests relatively recent local sources of PAHs in the study area. The combined hazard index for all metals and PAHs was from 2.26E - 02 to 1.18E - 01, which was lower than 1, suggesting minimal risk to humans. Only Arsenic (As) was evaluated with potential carcinogenic risks of 7.27E - 06 to 2.50E - 05. The study represents the preliminary implementation of a well-defined methodology into the environmental management process and provides a scientific basis for the pollutant controlment order.

Determination of benzo[a]pyrene in charcoal grilled meat samples by HPLC with fluorescence detection

In this study, an HPLC procedure for the quantitative determination of benzo[a]pyrene (BaP) in charcoal grilled meat samples has been applied to the analysis of the Turkish meat samples. The grilled meat samples were first treated in alkaline medium, then BaP was extracted into n-hexane phase, purified on XAD-2 column and eluted with n-hexane/dichloromethane mixture (9:1,v/v). Separation and quantitative determination of BaP has been carried out by a C18 reversed phase column mounted HPLC with a fluorescence detection of 254-355 nm (excitation-emission). The BaP levels determined in grilled and over-grilled lamb and beef meats were 43.80 +/- 1.80 microg/kg, 31.33 +/- 0.94 microg/kg and 62.60 +/- 3.72 microg/kg, 37.60 +/- 3.84 microg/kg, respectively.

Optimisation of the GC-MS conditions for the determination of the 15 EU foodstuff priority polycyclic aromatic hydrocarbons

European legislation has recently established a list of 15 priority polycyclic aromatic hydrocarbons (PAHs) to be monitored in foodstuff. Thus, the accurate determination of these compounds has become a highly relevant issue. The fact that some of these European Union (EU) PAHs differ from those typically analysed, requires the re-evaluation of the instrumental conditions for the proper determination of the new target compounds. In this study, the influence of the stationary phase and dimensions of the GC capillary column on the chromatographic resolution of the 15 EU PAHs has been investigated. Apolar (DB-5 type) and medium polar (DB-17 type) stationary phases with different lengths and film thickness have been evaluated for the separation of the target compounds, with special emphasis on those coelutions involving isomers such as the three benzofluoranthenes included in the EU PAHs. In addition, the influence of the injection technique and the column dimensions on the recovery of the high molecular mass PAHs has been studied. A programmable temperature vaporising (PTV) injector has been used in three different operational modes and the results were compared to those obtained using on-column injection. The experimental parameters involved in the injection step were optimised by using experimental design.

Application of surfactants and microemulsions to the extraction of pyrene and phenanthrene from soil with three different extraction methods

In the present work, the use of surfactants and oil-in-water (O/W) microemulsions as alternative extractants in accelerated solvent extraction (ASE) for the extraction of polycyclic aromatic hydrocarbons (pyrene and phenanthrene) from soils was investigated. In particular, the effect of each individual component within the microemulsions, i.e., oil phase, surfactant and co-surfactant, and extraction conditions on the percentage recovery was systematically studied. When compared to the water and organic solvent, the important findings were that the common surfactant solutions at the concentrations above their critical micelle concentrations (CMC) were shown to enhance the percentage recovery at the lower extraction temperature. Moreover, the highest percentage recovery can be obtained using microemulsion as the extractant. The chemical component within the microemulsions and relative amounts of the oil phase appeared to play a much more significant role in ensuring high percentage recovery. Finally, an overall comparison between the percentage recoveries obtained with ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and ASE using organic solvents, surfactants and microemulsions as extractants was exhibited.

Use of compressed fluids for sample preparation: Food applications

This review attempts to provide an updated overview (including works published till June 2006) on the latest applications of compressed fluids as sample preparation techniques for food analysis. After a general review of the principles of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE; also called accelerated solvent extraction, ASE or subcritical water extraction, SWE, when water is employed as extraction solvent), the principal applications of such techniques in the mentioned fields of food and natural products are described, discussing their main advantages and drawbacks.

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.

Inhalation and dietary exposure to polycyclic aromatic hydrocarbons and urinary 1-hydroxypyrene in non-smoking university students

OBJECTIVE

To examine which exposure pathway, dietary or inhalation, contribute more to the exposure to, and/or internal dose of, polycyclic aromatic hydrocarbons (PAHs) of non-smoking Japanese.

METHODS

Duplicated diet, personal air samples and 24-h urine were collected from 14 non-smoking male university students without occupational exposure and the concentrations of PAHs in diet and air and that of 1-hydroxypyrene (1-OHP) in urine were measured with HPLC-fluorescence detector.

RESULTS

Daily dietary exposure contributed more than 90% of the total (diet + inhalation) daily exposure level for pyrene (diet/inhalation: 757/1.2 ng/day), benzo[k]fluoranthene (25/1.7 ng/day) and benzo[a]pyrene (91/2.1 ng/day). Urinary excretion of 1-OHP (median: 37 ng/day) was statistically significantly correlated only with dietary PAHs exposure level but not with inhalation.

CONCLUSION

Countermeasures to lower PAHs levels in atmosphere has been successful in Japan and more attention should be directed to dietary exposure to PAHs for reducing cancer risk in general population.

Optimization of a microwave-assisted extraction method for the analysis of polycyclic aromatic hydrocarbons from fish samples

A microwave-assisted extraction (MAE) procedure has been developed and optimized for the extraction of six regulated polycyclic aromatic hydrocarbons (PAHs) from muscle samples of polluted fish. The procedure involves the simultaneous microwave-assisted extraction of PAHs with n-hexane and the lipids hydrolysis with potassium hydroxide. Experimental design methodology allows a quick and robust optimization of operational parameters such as the extraction time, temperature, and solvent volumes. In these final optimized conditions, the procedure can be applied to a vast range of fat containing fish samples without significant changes, thus enabling its routine use. Recoveries around 90% for the studied compounds benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, and indene[1,2,3-cd]pyrene and quantification limits (between 0.07 and 0.53 ng/g dry weight) far below the regulated limits, have been obtained. The procedure is applied to several different fish samples. Further, accuracy validation using NIST SRM 2977 reference material was carried out.

An automated extraction approach for isolation of 24 polyaromatic hydrocarbons (PAHs) from various marine matrixes

An efficient and selective analytical method for determination and quantification of 24 various polyaromatic hydrocarbons (PAHs) in blue mussel (Mytilus edulis), salmon fillet (Salmo salar), fish oil and fish feed has been developed. The samples were extracted by means of accelerated solvent extraction (ASE) technique followed by a purification step with gel permeation chromatography (GPC). Identification and quantification were performed by using GC/MS. The novel combination of silica and alumina in the extraction step furnishes highly purified analytes for the most of the 24 PAHs investigated, and thus a fast and selective analytical method is developed. A small limitation with the method concerns the quantification of acenaphthene (Ace), fluorene (Fl), pyrene (Py) and benzo[a]anthracene (BaA), as the found values for these compounds do not match the certified values (SRM 2977, mussel tissue). Chrysene (Chr) and triphenylene (Tph) give unresolved peaks. The limits of detection (LOD) and limits of quantification (LOQ) found for benzo[a]pyrene (BaP) were 1.7 and 0.44 pg/g (LOD), and 5.8 and 1.5 pg/g (LOQ) for salmon fillet and blue mussel, respectively. This is in a very good accordance with respect to the European Community legislation for official control of BaP levels in foodstuff. The method may be used for qualitative identification of petroleum compounds in marine matrixes.

Optimization of the procedure for the determination of polycyclic aromatic hydrocarbons and their derivatives in fish tissue: Estimation of measurements uncertainty

Three alternative procedures were employed for the isolation of polycyclic aromatic hydrocarbons (PAHs; 15 of 16 US EPA priority pollutants and benzo[e]pyrene), their methyl-derivatives and sulphur analogues from fish tissue: (1) Soxhlet extraction, (2) batch extraction enhanced by sonication, and (3) saponification of the sample followed by re-extraction of analytes into hexane. Soxhlet extraction using hexane-acetone (1:1, v/v) was the most efficient extraction technique, with analyte recoveries in the range 70-108%. Within optimization of the clean-up step, several types of gel permeation chromatography (GPC) systems were tested: two types of polystyrene divinylbenzene copolymer gels (PSDVB), both 'soft' gel type (Bio-Beads S-X3) and 'rigid' gels type (PL gel and Envirogel) in combination with various mobile phases were compared. Bio-Beads S-X3 and mobile phase chloroform were the most appropriate for purifying of crude extracts before the final determinative step. High-performance liquid chromatography with fluorimetric detection (HPLC/FLD) was used for identification and quantification of PAHs in purified fish extracts. The uncertainties of PAHs measurements were estimated by employing two alternative approaches. Both provided similar results: the expanded uncertainties obtained for individual PAHs by the 'top-down' approach were in the range 9-53%, their values resulting from application of the 'bottom-up' approach were in the range 16-52%.

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.

Troubleshooting with cell blanks in PLE extraction

The blank extracts obtained from the pressurized liquid extraction (PLE) of a 11 mL empty cell of ASE 200 were analysed by GC-FID and GC-ECD and many interfering peaks were detected, which could difficult the trace analysis of persistent organic pollutants (i.e. polycyclic aromatic hydrocarbons, aliphatic hydrocarbons and organochlorine pesticides). These interfering compounds were identified as phthalates, silicones and organic acids and their sources were established. A solution to this analytical trouble is a previous extraction step of the empty cell under the same conditions optimised for the sample extraction.

Determination of polynuclear aromatic hydrocarbons in marine samples of Siokolo Fishing Settlement

Analysis for the presence of 16 priority polynuclear aromatic hydrocarbons (PAHs) was carried out in fish, sediment and water samples of a fishing settlement in the Niger Delta region of Nigeria which is supposed to be extensively polluted by seepages from oil discharge terminals. The determination and quantification of PAHs in water, fish and sediment samples were done by GC-MS with the aid of isotopically labeled internal standards. The 16 priority PAHs, namely naphthalene, acenaphthylene, acenaphthene, flourene, phenanthrene, anthracene, flouranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]flouranthene, benzo[k]flouranthene, benzo[a]pyrene, benzo[ghi]perylene, dibenz[a,h]anthracene and indeno[1,2,3-cd]pyrene, were found to be present in significant amount in all three samples.

PAHs and metals in the soils of inner-city and suburban New Orleans, Louisiana, USA

Representative soil samples of an inner-city and suburban community (n = 19 each) are evaluated for 16 polycyclic aromatic hydrocarbons-PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo[k]fluoranthene, benzo[j]fluoranthene, benzo(a)pyrene, indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene and benzo[g,h,i]perylene) and nine metals (Pb, Zn, Cd, Mn, Ni, Cu, Cr, Co and V). Surface (2.5cm deep) samples were air-dried and sieved (2mm USGS #10). Accelerated solvent extraction was used for PAH preparation prior to analysis with gas chromatography-mass spectrometry. Metals were extracted at a 5:1 ratio of 1mol nitric acid to soil, shaken at room temperature, centrifuged, filtered and analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Total PAHs (median 2927ngg(-1) versus 731ngg(-1)) and the total metals (median 1323μgg(-1) versus 183μgg(-1)) summarize differences (P < 0.0001) between the inner-city and suburb, respectively. A strong association exists between PAHs and metals for all 38 soil samples (correlation coefficient = 0.831, P < 0.00001). In terms of the specific sites of accumulation, both PAHs and metals show the same pattern: busy streets > foundations > residential streets > open areas. This study provides real-world data about various chemical mixtures which may be a factor of possible health disparities in sensitive populations, especially children, in different communities of New Orleans.