Quantitative determination of 16 polycyclic aromatic hydrocarbons in soil samples using solid-phase microextraction

Solid-phase microextraction - a future technique in pharmacology and coating trends

Traditional sample preparation techniques based on liquid-liquid extraction (LLE) or solid-phase extraction (SPE) often suffer from a major error due to the matrix effects caused by significant co-extraction of matrix components. The implementation of a modern extraction technique such as solid-phase microextraction (SPME) was aimed at reducing analysis time and the use of organic solvents, as well as eliminating pre-analytical and analytical errors. Solid-phase microextraction (SPME) is an innovative technique for extracting low molecular weight compounds (less than 1500 Da) from highly complex matrices, including biological matrices. It has a wide range of applications in various types of analysis including pharmaceutical, clinical, metabolomics and proteomics. SPME has a number of advantages over other extraction techniques. Among the most important are low environmental impact, the ability to sample and preconcentrate analytes in one step, simple automation, and the ability to extract multiple analytes simultaneously. It is expected to become, in the future, another method for cell cycle research. Numerous available literature sources prove that solid-phase microextraction can be a future technique in many scientific fields, including pharmaceutical sciences. This paper provides a literature review of trends in SPME coatings and pharmacological applications.

Using solid-phase microextraction during ultrasound reveals higher aqueous PAHs release from contaminated sediment

Ultrasound (US) releases polycyclic aromatic hydrocarbons (PAHs) from contaminated creosote sediments and degrades PAHs in aqueous solution. However, it is unclear how much PAHs release occurs during active US compared to after US is stopped. In this study, solid-phase microextraction (SPME) was used to determine aqueous PAH concentrations desorbed from Little Scioto River creosote contaminated sediment during exposure to 20 kHz ultrasound (US) at a power of 430 W L^-1. First, SPME fiber-water partition coefficients,K_SPME, were experimentally determined and shown to be comparable with previous studies. Next, PAH concentrations released into aqueous solution were determined by sequentially exposing fresh, conditioned SPME fibers in a reactor containing the contaminated sediment and DI for 10 min periods. Three consecutive 10 min periods each were measured during US and after US. Compared to mixing only, PAHs desorbed during ultrasound was significantly higher. In addition, for phenanthrene, anthracene, and fluoranthene, US showed significantly higher aqueous concentrations during US compared with after US. For these less soluble PAHs, desorption into the aqueous phase reaches and surpasses expected equilibrium aqueous concentrations. However, when US is ceased, PAHs appear to resorb onto sediment resulting in the lower concentrations measured in these PAH compounds after US that are similar to expected equilibrium aqueous concentrations. Typical analytical extraction methods for determining the effects of US require stopping treatment and may underestimate the potential US has for release of contaminants from sediment during US. Using SPME during US treatment reveals that the concentration of PAHs during US may surpass the expected equilibrium aqueous concentration of some PAHs congeners. To our knowledge, this higher concentration observed during US compared to after US has not been shown previously.

In Vivo Solid-Phase Microextraction and Applications in Environmental Sciences

Solid-phase microextraction (SPME) is a well-established sample-preparation technique for environmental studies. The application of SPME has extended from the headspace extraction of volatile compounds to the capture of active components in living organisms via the direct immersion of SPME probes into the tissue (in vivo SPME). The development of biocompatible coatings and the availability of different calibration approaches enable the in vivo sampling of exogenous and endogenous compounds from the living plants and animals without the need for tissue collection. In addition, new geometries such as thin-film coatings, needle-trap devices, recession needles, coated tips, and blades have increased the sensitivity and robustness of in vivo sampling. In this paper, we detail the fundamentals of in vivo SPME, including the various extraction modes, coating geometries, calibration methods, and data analysis methods that are commonly employed. We also discuss recent applications of in vivo SPME in environmental studies and in the analysis of pollutants in plant and animal tissues, as well as in human saliva, breath, and skin analysis. As we show, in vivo SPME has tremendous potential for the targeted and untargeted screening of small molecules in living organisms for environmental monitoring applications.

6-Phenylhexyl silane derivatized, sputtered silicon solid phase microextraction fiber for the parts-per-trillion detection of polyaromatic hydrocarbons in water and baby formula

We report the fabrication of 6-phenylhexylsilane derivatized, sputtered silicon, solid phase microextraction fibers that show parts per trillion detection limits for polyaromatic hydrocarbons, and negligible carry over and phase bleed. Their fabrication involves sputtering silicon on silica fibers under various conditions. Six different fibers were evaluated by generating three different thicknesses of sputtered silicon at two different throw distances, which altered the morphologies of the silicon surfaces. All of the fibers were coated with similar thicknesses of 6-phenylhexylsilane (ca. 2 nm). These fibers were characterized with multiple analytical techniques. The optimum fiber configuration was then used to analyze polyaromatic hydrocarbons via direct immersion, gas chromatography mass spectrometry. Our best fiber for the extraction of low molecular weight polyaromatic hydrocarbons in water had similar performance to that of a commercial fiber. However, our fiber demonstrated ca. 3 times the extraction efficiency for higher molecular weight polyaromatic hydrocarbons. In addition, it outperformed the commercial fiber by showing better linearity, repeatability, and detection limits. A method for analyzing polyaromatic hydrocarbons in baby formula was developed, which showed very good linearity (0.5-125 ppb), repeatability (2-26%), detection limits (0.12-0.81 ppb), and recoveries (103-135%). In addition, our fiber showed much less (negligible) carry over and phase bleed than the commercially available fibers.

Boron nitride modified reduced graphene oxide as solid-phase microextraction coating material for the extraction of seven polycyclic aromatic hydrocarbons from water and soil samples

A novel hexagonal boron nitride modified reduced graphene oxide material was synthesized and used as the adsorbent for the solid-phase microextraction of seven polycyclic aromatic hydrocarbons from water and soil samples prior to their detection by gas chromatography-flame ionization detector. Under optimal conditions, the linear response range of the analytes for water sample is 0.25-50 ng/mL with the correlation coefficients (r) ranging between 0.9953 and 0.9996. The linear range for soil sample is 1.0-400 ng/g with r ranging from 0.9959 to 0.9999. On the basis of the signal-to-noise ratio of 3, the limits of detections for the analytes ranged from 0.05 to 0.15 ng/mL for water samples, and from 0.3 to 0.5 ng/g for soil samples. The relative recoveries of the seven polycyclic aromatic hydrocarbons for water and soil samples were in the range of 79.55-120.0 and 78.76-120.8%, respectively. The relative standard deviations for the determination of the analytes in water and soil samples were lower than 11 and 10%, respectively. The method is simple and suitable for the determination of polycyclic aromatic hydrocarbon residues in water and soil samples.

Evaluation of Reductions in Fume Emissions (VOCs and SVOCs) from Warm Mix Asphalt Incorporating Natural Zeolite and Reclaimed Asphalt Pavement for Sustainable Pavements

Conventional asphalt mixtures used for road paving require high manufacturing temperatures and therefore high energy expenditure, which has a negative environmental impact and creates risk in the workplace owing to high emissions of pollutants, greenhouse gases, and toxic fumes. Reducing energy consumption and emissions is a continuous challenge for the asphalt industry. Previous studies have focused on the reduction of emissions without characterizing their composition, and detailed characterization of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) in asphalt fumes is scarce. This communication describes the characterization and evaluation of VOCs and SVOCs from asphalt mixtures prepared at lower production temperatures using natural zeolite; in some cases, reclaimed asphalt pavement (RAP) was used. Fumes were extracted from different asphalt mix preparations using a gas syringe and then injected into hermetic gas sample bags. The compounds present in the fumes were sampled with a fiber and analyzed by gas-liquid chromatography coupled to mass spectrometry (GC/MS). In general, the preparation of warm mix asphalts (WMA) using RAP and natural zeolite as aggregates showed beneficial effects, reducing VOCs and SVOCs compared to hot mix asphalts (HMA). The fumes captured presented a similar composition to those from HMA, consisting principally of saturated and unsaturated aliphatic hydrocarbons and aromatic compounds but with few halogenated compounds and no polycyclic aromatic hydrocarbons. Thus, the paving mixtures described here are a friendlier alternative for the environment and for the health of road workers, in addition to permitting the re-use of RAP.

Green solid-phase microextraction fiber coating based on the metal-organic framework CIM-80(Al): Analytical performance evaluation in direct immersion and headspace using gas chromatography and mass spectrometry for the analysis of water, urine and brewed coffee

A new solid-phase microextraction (SPME) fiber coating was prepared by the immobilization of the metal-organic framework (MOF) CIM-80(Al) on nitinol wires by a green in situ growth approach, using an aqueous synthetic approach, and without the need of any additional material to ensure the attachment of the MOF to the nitinol support. The coating was used for the development of headspace (HS) and direct immersion (DI) SPME methods in combination with gas chromatography and mass spectrometry (GC-MS) for the determination of polycyclic aromatic hydrocarbons (PAHs) as model compounds. Both methods were optimized and validated using the MOF-based fiber together with the commercial polydimethylsiloxane (PDMS) fiber. The MOF extraction phase exhibited superior analytical performance for most of the PAHs in HS-SPME mode (and particularly for less volatiles), while the PDMS fiber presented better results in the DI-SPME method. The analytical performance of the MOF sorbent coating in HS- and DI-SPME methods was also evaluated in urine and brewed coffee samples, without requiring any pretreatment step apart from dilution for DI-SPME experiments, thus showing suitability of the novel coatings for the analysis of complex samples. The proposed CIM-80(Al) fiber was efficient and biocompatible (for using a low cytotoxic sorbent and a biocompatible core support), and it also demonstrated stability and robustness, with inter-fiber (and inter-day) relative standard deviation values lower than 19%, and reusability for more than 80 extraction cycles using 280 °C as desorption temperature.

The ecological impact of mineral exploitation in the Russian Arctic: A field-scale study of polycyclic aromatic hydrocarbons (PAHs) in permafrost-affected soils and lichens of the Yamal-Nenets autonomous region

Forty soil and lichen samples and sixteen soil horizon samples were collected in the mining and surrounding areas of the Yamal-Nenets autonomous region (Russian Arctic). The positive matrix factorization (PMF) model was used for the source identification of PAHs. The results of the source identification showed that the mining activity was the major source of PAHs in the area, and that the mining influenced the surrounding natural area. The 5+6-ring PAHs were most abundant in the mining area. The lichen/soil (L/S) results showed that 2+3-ring and 4-ring PAHs could be transported by air and accumulated more in lichens than in the soil, while 5+6-ring PAHs accumulated more in the soil. Strong relationships between the quotient of soil/lichen (Q_SL) and Log K_OA and Log P_L and between the quotient of lichen/histic horizon soil and K_OW were observed. In addition, hydrogeological conditions influenced the downward transport of PAHs. Particularly surprising is the discovery of the high levels of 5 + 6 rings in the permafrost table (the bottom of the active layer). One hypothesis is given that the global climate change may lead to further depth of active layer so that PAHs may migrate to the deeper permafrost. In the impact area of mining activities, the soil inventory for 5+6-ring PAHs was estimated at 0.14 ± 0.017 tons on average.

Concentration and Source Assessment of Polycyclic Aromatic Hydrocarbons in the Street Soil of Ma'an City, Jordan

In this study, the levels of polycyclic aromatic hydrocarbons (PAHs) were determined in the street soil of Ma'an City, Jordan. The probable sources of PAHs in the soils were estimated by using diagnostic ratios. PAHs were extracted from soil samples via the ultrasonic extraction method using three portions of 20 mL of n-hexane/acetone mixture. The most priority environmental protection agency 13 PAHs were determined in the extract using gas chromatography-mass spectrometer. The results showed that average concentrations of ∑13PAHs ranged from 77.0 to 917.4 ng/g, and the 3- and 4-rings PAHs were the most abundant PAHs detected in the soil samples (~ 60% of the PAH total concentrations). The ratios showed that the PAHs in Ma'an's street soil have both petrogenic and pyrogenic sources. Pearson's correlation coefficient analysis showed that the content of ∑13PAHs is directly correlated to the total organic matter (TOM) in the soil. Analysis of variance indicated that Ma'an city mostly had the same sources for ∑13PAHs.

Ratiometric SERS detection of polycyclic aromatic hydrocarbons assisted by β-cyclodextrin-modified gold nanoparticles

A surface-enhanced Raman scattering (SERS) method is described for the determination of trace polycyclic aromatic hydrocarbons (PAHs) in the environment efficiently and economically. Detection sensitivity is improved by modifying gold nanoparticles (AuNPs) with 4-mercaptophenylboronic acid (4-MPBA) conjugated to β-cyclodextrin (β-CD) as a new method for ratiometric determination of PAHs in solution. Pyrene (with a Raman band at 580 cm^-1) and anthracene (750 cm^-1) were used as the model analytes, while 4-MPBA (1570 cm^-1) was used as the internal reference to normalize the SERS signals. The intensity ratios of pyrene/4-MPBA increase linearly in the 2 to 10 nM pyrene concentration range, and the intensity ratios of anthracene/4-MPBA increase linearly in the 10 to 100 nM anthracene concentration range. The detection limits are 0.4 nM for pyrene and 4.4 nM for anthracene. This method was applied to the determination of the two analytes in soil sample extracts and the recoveries of pyrene (at levels of 236 ng∙g^-1 and 170 ng∙g^-1) and anthracene (334 ng∙g^-1 and 510 ng∙g^-1) agreed well with the results from GC-MS analyses. The good recovery rates (101.8% and 102.5% for pyrene and 106.4% and 101.7% for anthracene) confirmed the reliability of the method. Graphical abstract Schematic illustration of SERS signal enhancement of pyrene, as an example of polycyclic aromatic hydrocarbons, by β-cyclodextrin modified gold nanoparticles.

Environmentally friendly solid-phase microextraction coupled with gas chromatography and mass spectrometry for the determination of biogenic amines in fish samples

In this work, a facile and environmentally friendly solid-phase microextraction assay based on on-fiber derivatization coupled with gas chromatography and mass spectrometry was developed for determining four nonvolatile index biogenic amines (putrescine, cadaverine, histamine, and tyramine) in fish samples. In the assay, the fiber was firstly dipped into a solution with isobutyl chloroformate as derivatization reagent and isooctane as extraction solvent. Thus, a thin organic liquid membrane coating was developed. Then the modified fiber was immersed into sample solution to extract four important bioamines. Afterwards, the fiber was directly inserted into gas chromatography injection port for thermal desorption. 1,7-Diaminoheptane was employed as internal standard reagent for quantification of the targets. The limits of detection of the method were 2.98-45.3 μg/kg. The proposed method was successfully applied to the detection of bioamines in several fish samples with recoveries ranging 78.9-110%. The organic reagent used for extraction was as few as microliter that can greatly reduce the harm to manipulator and environment. Moreover, the extraction procedures were very simple without concentration and elution procedures, which can greatly simplify the pretreatment process. The assay can be extended to the in situ screening of other pollutant in food safety by changing the derivatization reagent.

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.

Simultaneous determination of 16 polycyclic aromatic hydrocarbons in reclaimed water using solid-phase extraction followed by ultra-performance convergence chromatography with photodiode array detection

A new fast and effective analysis method has been developed to simultaneously determine 16 polycyclic aromatic hydrocarbons in reclaimed water samples by ultra-performance convergence chromatography with photodiode array detection and solid-phase extraction. The parameters of ultra-performance convergence chromatography on the separation behaviors and the crucial condition of solid-phase extraction were investigated systematically. Under optimal conditions, the 16 polycyclic aromatic hydrocarbons could be separated within 4 min. The limits of detection and quantification were in the range of 0.4-4 and 1-10 μg/L in water, respectively. This approach has been applied to a real industrial wastewater treatment plant successfully. The results showed that polycyclic aromatic hydrocarbons were dramatically decreased after chemical treatment procedure, and the oxidation procedure was effective to remove trace polycyclic aromatic hydrocarbons.

Determination of low levels of polycyclic aromatic hydrocarbons in soil by high performance liquid chromatography with tandem fluorescence and diode-array detectors

Risk assessment of polycyclic aromatic hydrocarbons (PAHs) contaminated soil and source apportionment require accurate analysis of the concentration of each PAH congener in the soil. However, determination of low level PAH congeners in soil is difficult because of similarity in the chemical properties of 16 PAHs and severe matrix interferences due to complex composition of soils. It is therefore imperative to develop a sensitive and accurate method for determination of low level PAHs in soil. In this work, high performance liquid chromatography equipped with fluorescence and diode-array detectors (HPLC-FLD-DAD) was used to determine the concentration of 16 PAHs in soil. The separation of the 16 PAHs was achieved by optimization of the mobile phase gradient elution program and FLD wavelength switching program. Qualitative analysis of the 16 PAHs was based on the retention time (RT) and each PAH specific spectrum obtained from DAD. In contrast, the quantitative analysis of individual PAH congeners was based on the peak areas at the specific wavelength with DAD and FLD. Under optimal conditions the detection limit was in the range 1.0-9.5 μg L(-1) for 16 PAHs with DAD and 0.01-0.1 μg L(-1) for 15 PAHs with FLD, and the RSD of PAHs was less than 5% with DAD and 3% with FLD. The spiked recoveries were in the range 61-96%, with the exception of NaP (<40%). The results show that HPLC-FLD-DAD can provide more accurate and reliable analysis of low level PAH congeners in soil samples.

Microwave-assisted headspace solid-phase microextraction to quantify polycyclic aromatic hydrocarbons in pine trees

A methodology for the extraction and quantification of 16 polycyclic aromatic hydrocarbons (PAHs) based on microwave-assisted extraction coupled with headspace solid-phase microextraction followed by gas chromatography/mass spectroscopy was validated for needles and bark of two pine species (Pinus pinaster Ait. and Pinus pinea L.). The limits of detection were below 0.92 ng g(-1) (dry weight) for needles and below 0.43 ng g(-1) (dw) for bark. Recovery assays were performed with two sample masses spiked at three levels and the overall mean values were between 70 and 110 % for P. pinaster and 75 and 129 % for P. pinea. In the first species, the increase in sample mass lowered the recoveries slightly for most PAHs, whereas for the second, the recoveries were higher for the needles. Naturally contaminated samples from 4 sites were analysed, with higher levels for urban sites (1,320 and 942 ng g(-1) (dw) vs. 272 and 111 ng g(-1) (dw) for needles and 696 and 488 ng g(-1) (dw) vs. 270 and 103 ng g(-1) (dw) for bark) than for rural ones and also for P. pinaster samples over P. pinea. It is also shown that gas-phase PAHs are predominant in the needles (over 65 % of the total PAHs) and that the incidence for particulate material in bark, reaching 40 % as opposed to a maximum below 20 % for the needles. The method has proved to be fit and improved some of the existing approaches, on the assessment of particulate PAHs and bark levels.

Spray desorption collection of free fatty acids onto a solid phase microextraction fiber for trap grease analysis in biofuel production

Spray desorption collection (SDC) is a sample collection and preparation method that allows for the collection of soluble chemical compounds directly from solid surfaces. Here the analysis of trap grease, a potential biofuel feedstock, is demonstrated by combining SDC with solid phase micro-extraction (SPME) collection followed by direct GC-MS analysis. The SPME fiber collects droplets of solvent, which has picked up analytes from the solid sample surface. It is found that the SDC-SPME combination is a simple and convenient method to collect sample components from surfaces when they are less volatile than heptanoic acid, while the collection efficiency of highly volatile compounds is increasingly reduced due to the purging effect of the nebulising gas. In a real trap grease analysis the SDC-SPME method was able to analyze both the longer chain fatty acids in the sample, important for energy production evaluation of the sample, as well as volatile sample components down to pentanoic acid, which may add to off-odours produced during biofuel use.