Evaluation of the Soil Contamination of Tangier (Morocco) by the Determination of BTEX,PCBs, and PAHs

Benzene, toluene, ethylbenzene, and xylenes (BTEX), twelve polycyclic aromatic hydrocarbons (PAHs) and seven polychlorinated biphenyls (PCBs), were selected as pollutants to evaluate the contamination of soils in the urban and industrial areas of Tangier (Morocco). PAHs and PCBs were determined by gas chromatography-mass spectrometry (GC-MS) after a microwave-assisted extraction (MAE) and gel permeation chromatography (GPC) clean-up. BTEX were directly determined by head-space GC-MS. Results obtained in this study show the presence of high levels of BTEX and PAHs in the soil near the urban waste deposit. However, the analysis of pollutants in the other sampling sites provided comprehensive evidence that soils of Tangier city are not contaminated.     

A Rapid Screening Method for the Determination of Seventy Pesticide Residues in Soil Using Microwave-Assisted Extraction Coupled to Gas Chromatography and Mass Spectrometry

A rapid screening method using microwave-assisted extraction (MAE) in combination with gas chromatography and mass spectrometry for the determination of 70 pesticide residues in soil was established. The pesticides included 27 organophosphorus pesticides (OPPs), 29 organochlorine pesticides (OCPs), nine pyrethroids, and five carbamates. Parameters that could affect the efficiency of extraction, such as temperature, time, and solvent, were investigated. The condition of the extraction, under which recoveries of all 70 pesticides ranged from 70% to 120%, was optimized with a 1:1 (V/V) mixture of acetone and hexane, a temperature of 100°C, and an extraction time of 10 min. All compounds studied could be recovered in good yields and with relative standard deviations (RSDs) lower than 20%. The linearity of the method for all the pesticides was greater than 0.99 over a concentration range of 0.1–5 μg/g. The detection limits varied from 0.5 to 211.25 ng/g. Interday and intraday precision analyses yielded RSDs of 1.2%–11.7% and 3.6%–15.1%, respectively. This method, which was as effective as Soxhlet extraction and accelerated solvent extraction (ASE), proved to be accurate and precise. When the proposed method was used to examine environmental samples, the obtained results were in good agreement with those obtained using Soxhlet extraction.     

Distribution characteristics,sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments from Haizhou Bay,China

Sixteen USEPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography–mass spectrometry. Twenty samples were collected from the surface sediments of Haizhou Bay in this survey. This research aimed to identify the PAHs' contamination level, composition pattern, pollution sources, and assess the ecological risk of PAHs. The results showed that the sum of PAH concentrations ranged from 116.6 ng g^?1 to 2414.9 ng g^?1 (mean: 662.42 ng g^?1), which is higher than the reported values for different wetlands worldwide. Three- and four-ring PAHs (accounts for more than 70% of the total PAH content) were predominant in the wetland sediment. The PAHs source distribution in the surface sediments were determined using diagnostic ratio and PCA/MLR. Consequently, multiple PAHs sources were found. Of the total PAH, 79.25% was derived from vehicular emission, 20.75% from coal combustion. The effect range low/effect range median (ERL/ERM) values indicated a low toxicity risk level. However, the fluoranthene concentrations exceeded the ERL level, and even the ERM level, in some stations. The mean effects range–median quotient (M-ERM-Q) suggests a low ecological risk for the PAHs in the sediments.     

Optimized extraction of polycyclic aromatic hydrocarbons from contaminated soil samples

A comparison of Soxhlet extraction and a new extraction technique, fluidized-bed extraction, has been conducted. The extraction of polycyclic aromatic hydrocarbons (PAHs) by this new technique has been optimized considering as experimental variables the variation of the number of extraction cycles and the holding time after reaching the heating temperature by means of a surface response design. The significance of the operational parameters of the fluidized-bed extraction onto the performance characteristics has been investigated. For the determination of the analytes, a cleanup of the extracts followed by gas chromatography with mass spectrometric detection was used. The accuracy of the method was established by extraction and analysis of a reference material, supplied from the European Commission's Joint Research Centre.     

Determination of selected monohydroxy metabolites of 2-, 3- and 4-ring polycyclic aromatic hydrocarbons in urine by solid-phase microextraction and isotope dilution gas chromatography-mass spectrometry

Eighteen monohydroxy polycyclic aromatic hydrocarbon metabolites (OH-PAHs) representing polycyclic aromatic hydrocarbons (PAHs) containing up to four rings in human urine have been measured. The method includes the addition of carbon-13 labeled internal standards, enzymatic hydrolysis, and solid-phase microextraction followed by gas chromatography with high-resolution mass spectrometry. By using response factors calculated with the carbon-13 labeled standards, results are presented for calibration, relative standard deviations and analyte levels from an unspiked human urine pool. The method detection limits ranged from 0.78 ng/l for hydroxyphenanthrenes to 15.8 ng/l for 1-hydroxynaphthalene, and the recoveries ranged between 6% for hydroxychrysene and 47% for 1-hydroxypyrene. The relative standard deviation was lowest for 3-hydroxyphenanthrene at 2.4% and went up to 18.7% for 6-hydroxychrysene. The method was calibrated from 10 to 1200 ng/l. Eleven of the 18 metabolites were found in background pooled urine samples. This validated method is a convenient and reliable tool for determining urinary OH-PAHs as biomarkers of exposure to eight PAHs.     

Extraction Efficiency and HPLC Determination of Imidacloprid in Soil

Two extraction methods were successfully applied to study the extraction of imidacloprid from soil. The first method, using a mix of acetone and hexane, was based on Soxhlet extraction, and the second method, using acetonitrile, methanol, and water, was a modified version of a liquid extraction method. Quantification was performed by reversed-phase High Performance Liquid Chromatography (HPLC) with Diode Array Detection (DAD) at 270 nm using 40:60 (v/v) acetonitrile/water as a mobile phase. The mean recoveries for imidacloprid from soil ranged from 82.6 to 109%, with a relative standard deviation between 1.9 and 5.6% for both extraction methods. The detector linearity and the reproducibility of the method proved to be very precise. The limits of detection were 0.08 and 0.06 mg kg^?1 for liquid extraction and Soxhlet extraction, respectively. Overall, the efficiency of the Soxhlet extraction at lower concentrations was better than at higher concentrations, while liquid extraction proved efficient for all spiked levels. Liquid extraction performed better at higher concentrations compared to Soxhlet extraction. Taken together, our study suggests that the analysis of imidacloprid in soil can be performed with the modified liquid extraction method with a higher recovery and a lower RSD than Soxhlet extraction.     

Polycyclic Aromatic Hydrocarbon Profiles of Some Brands of Canned Fish in the Nigerian Market

Concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) were determined in selected popular brands of canned fish (mackerel, sardine, and tuna) consumed in Nigeria with a view to providing information on the health risk associated with consumption of these products. The concentrations of PAHs were measured by gas chromatography equipped with flame ionization detection (GC-FID) after dichloromethane/hexane extraction and clean-up. The concentrations of Σ16 PAHs in these brands of canned fish varied from 174.6 to 350.8 μg/kg, 187.4 to 592.5 μg/kg, and 204 to 264.6 μg/kg for mackerel, sardine, and tuna, respectively. Benzo(a)pyrene was detected in 48% of the investigated brands at concentrations higher than the maximum tolerable limit of 5 μg/kg. The daily intake of PAHs from the consumption of any brand of these canned fish ranged from not detected (nd) to 54.3 ng BaP/kg bw/day, nd to 56.4 ng PAH2/kg bw/day, nd to 86.4 ng PAH4/kg bw/day, and nd to 153.7 ng PAH8/kg bw/day. The estimated margin of exposure (MOE) values (BaP-MOE, PAH2-MOE, PAH4-MOE, and PAH8-MOE) in a significant proportion of the brands was less than 10,000, which indicates a potential health risk for the consumers of these brands of canned fish.     

Pilot-scale supercritical carbon dioxide extractions for the recovery of triacylglycerols from microalgae: a practical tool for algal biofuels research

We describe the preliminary extractions from a pilot-scale supercritical carbon dioxide (SC-CO₂) extractor for the isolation of algal lipids suitable for small-scale conversion to liquid hydrocarbon fuels. Flowable oils were recovered from SC-CO₂ extractions of lyophilized Nannochloropsis granulata. The extracted oils were determined to be composed primarily of triacylglycerols (TAG) by liquid chromatography–mass spectrometry analysis. Gravimetric lipid yield was increased significantly from 15.56 to 28.45 mg g^?1 ash-free dry weight (AFDW) with an increase in temperature from 50°C to 70°C, at 35 MPa over 270 min. Varying pressure had no significant effect on lipid yield. Liquid chromatography–mass spectrometry analysis of the SC-SO₂ extracts indicated that the TAG profile remained constant regardless of extraction pressure, and analysis of fatty acid methyl esters (FAME) revealed a uniform profile throughout all extraction conditions. Our optimized gravimetric lipid yields from N. granulata (28.45 mg g^?1 AFDW) were approximately half of the yields obtained by Soxhlet extraction with hexane (57.53 mg g^?1 AFDW); however, the FAME yields were similar regardless of extraction technique (18.23 mg FAME g^?1 and 17.35 mg FAME g^?1 AFDW from SC-CO₂ extraction and hexane extraction, respectively). Further extractions with Botryococcus braunii indicated that fatty acid extraction by SC-CO₂ was as efficient as hexane extraction. These results highlight the suitability of SC-CO₂ for large-scale oil extraction of microalgae for biofuel or biojet analyses due to its selectivity for TAG extraction.     

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography–mass spectrometry (GC–MS) analysis. A one-step derivatization using 100 μL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations of all targeted compounds showed good intra- and inter-day (within 7 days) precision (<10 %), and good stability (<20 %) within 4 days at room temperature (23–25 °C), or 7 days when stored at ?20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistical analysis of the concentrations of these targeted metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research.     

Development of a liquid chromatography tandem mass spectrometry method for the simultaneous determination of zearalenone,deoxynivalenol and their metabolites in pig serum

A sensitive and selective liquid chromatography tandem mass spectrometry method using negative electrospray ionisation (LC-ESI-MS/MS) was developed for the simultaneous determination of zearalenone (ZEN), deoxynivalenol (DON) and their metabolites α-zearalenol, β-zearalenol, zearalanone, α-zearalanol, β-zearalanol and de-epoxy-deoxynivalenol in pig serum. For method development, different sample preparation columns were tested for their suitability for extraction and clean up. Finally, preparation of serum samples was carried out using Oasis? HLB solid-phase extraction (SPE) columns. The analyte concentrations were determined by the use of isotopically labelled internal standards (IS). The method was in-house validated for all analytes. Calibration graphs (0.3–480 ng/ml) were prepared and high degree of linearity was achieved (r?≥?0.99). Results for method precision ranged between 2.7 and 21.5 % for inter-day and between 1.1 and 11.1 % for intra-day. The recoveries were in the range of 82–131 %. Limits of detection and quantification ranged 0.03–0.71 and 0.08–2.37 ng/ml, respectively. The method has been successfully used for quantitative determination of ZEN, DON and their metabolites in pig serum from a feeding trial with practically relevant ZEN and DON concentrations. This method is precise and reproducible and can be used as a multi-biomarker method to assess animal exposure to these mycotoxins and for diagnosis of intoxications.     

Concentrations and Health Risk of Polycyclic Aromatic Hydrocarbons in Some Brands of Biscuits in the Nigerian Market

Concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were determined in 40 brands of biscuits in the Nigerian market. The analyses were performed by gas chromatography-flame ionisation detection (GC-FID) after Soxhlet extraction of the sample with hexane/dichloromethane and clean-up of the extract. The concentrations of Σ16 PAHs in these biscuit samples were in the range of 35.7–645.3 μg kg^?1, 75.9–490.7 μg kg^?1, 91.5–537 μg kg^?1, 18.4–522.2 μg kg^?1, 123.5–393.8 μg kg^?1, 167.2–880 μg kg^?1, 136.5–316 μg kg^?1, and 135.5–241.6 μg kg^?1 for shortcake, digestives, cookies, shortbread, wafers, crackers, Pringles, and cabin, respectively. The concentrations of Σ8 carcinogenic PAHs in the samples ranged from not detected (nd)–323.3 μg kg^?1, 15.7–138 μg kg^?1, 9.7–312.9 μg kg^?1, nd–331.7 μg kg^?1, nd–220.9 μg kg^?1, nd–53.3 μg kg^?1, 18.4–56.6 μg kg^?1, and 6.6–170.8 μg kg^?1 for shortcake, digestives, cookies, shortbread, wafers, crackers, Pringles, and cabin, respectively. The margin of exposure (MOE), based on PAH8 as an indicator for the occurrence and effects of PAHs in food, was less than 10,000, the serious health effects value, in 30% and 8% of the brands for the child and adult scenarios, respectively.     

Accelerated Determination of Selenomethionine in Selenized Yeast: Validation of Analytical Method

The purpose of this study was to reduce the extraction time, to hours instead of days, for quantification of the selenomethionine (SeMet) content of selenized yeast. An accelerated method using microwave-assisted enzymatic extraction and ultrasonication was optimized and applied to certified reference material (selenized yeast reference material (SELM)-1). Quantitation of SeMet in the extracts was performed by liquid chromatography with inductively coupled plasma mass spectrometry. The limits of detection and quantitation were 5 ppb SeMet and 15 ppb SeMet respectively and the signal response was linear up to 1,500 ppb SeMet. The average recovery of spiked SeMet from the selenized yeast matrix was 97.7 %. Analysis of an SELM-1 using this method resulted in 100.9 % recovery of the certified value (3448?±?146 ppm SeMet). This method is suitable for fast reliable determination of SeMet in selenized yeast.     

Distribution patterns of selected PAHs in bulk peat and corresponding humic acids from a Swiss ombrotrophic bog profile

An ombrotrophic peat core was collected in 2005 from Etang de la Gruère, Jura Mountains, Switzerland. The concentrations of nine among the U.S. Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs) (i.e., acenaphthene, phenanthrene, fluorene, pyrene, fluoranthene, benzo[jbk]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene) were determined in both bulk peat and corresponding humic acids (HA) samples by gas chromatography equipped with a mass spectrometry detector (GC-MS). The maximum PAHs concentrations in peat (around 1,250 μg Σ PAHs kg^?1 dry matter) were found at 28–30 cm of depth, which correspond to ca. 1920–1930, when coal inputs to Switzerland reached their maximum level. Amongst the nine PAHs analyzed in the peat samples, pyrene (Pyr) was the predominant species, accounting for ca. 20–100% of the total PAHs throughout the profile. In the HA fraction, that represents 24.7% (average value) of the bulk peat, only phenanthrene (Phe), and sporadically Pyr and fluoranthene (Fth), were detected. In particular, HA showed Phe concentrations that were ten–150 times higher than corresponding bulk peat samples, thus suggesting its preservation against biodegradation due to the incorporation into HA molecules.     

Organochlorine,Organophosphoric and Organotin Contaminants,Aromatic and Aliphatic Hydrocarbons and Heavy Metals in Sediments of the Ports from the Polish Part of the Vistula Lagoon (Baltic Sea)

The concentrations of polycyclic aromatic and petroleum hydrocarbons, polychlorinated biphenyls, dioxins, organochlorine and organophosphoric pesticides, tributyltin and metals were determined in sediments of the approach fairways to the main ports in the Polish part of the Vistula Lagoon and of the Elbl?g River. Analyzed sediments contained low concentrations of all contaminants, except petroleum hydrocarbons. The average petroleum hydrocarbons’ (PHCs) concentration was 630 mg kg^?1, indicating significant pollution with petroleum hydrocarbons. The highest concentrations of analyzed contaminants were identified in the vicinity of Elbl?g, part of the Vistula Lagoon under the most anthropogenic pressure.     

Determination of polycyclic aromatic hydrocarbons in smoked meat products and smoke flavouring food additives

Formation, factors affecting concentrations, legal limits and occurrence of polycyclic aromatic hydrocarbons in smoked meat products and smoke flavour additives are briefly reviewed. The most used techniques such as thin-layer chromatography (TLC), gas chromatography (GC) and high-performance liquid chromatography (HPLC) are evaluated. Also, sample preparation, pre-separation procedures, separation and detection systems being used for determination are discussed with emphasis to latest development in applied food analysis and the chosen data regarding the concentration of polycyclic aromatic hydrocarbons in smoked meat products and smoke flavour additives are summarised.     

Recent methods for the determination of volatile and non-volatile organic compounds in natural and purified drinking water

Four analytical protocols for the extraction and preconcentration of organic residues in natural or purified drinking water were investigated and compared: closed loop stripping analysis; simultaneous extraction—distillation; purge and trap analysis; continuous liquid—liquid extraction. Organic extracts were submitted to a variety of separation and identification techniques. Volatiles were determined by conventional capillary column gas chromatography with tandem mass spectrometry, using triple-stage quadrupole instruments. Non-volatile and thermally labile molecules were investigated by several different techniques (high-temperature gas chromatography, capillary column supercritical fluid chromatography, pyrolysis gas chromatography—mass spectrometry, thermospray liquid chromatography with tandem mass spectrometry and conventional fast-atom bombardment with tandem mass spectrometry). Several samples recently examined in the laboratory provide examples of this multitechnique approach for a more complete knowledge of the organic carbon distribution in water-dissolved organic matter, taking into account organic substances with widely different volatilities, polarities and thermal stabilities.     

Distribution,sources, and health risk assessment of polycyclic aromatic hydrocarbons in dust from urban environment in the Niger Delta,Nigeria

The concentrations of the 16 U.S. Environmental Protection Agency polycyclic aromatic hydrocarbons (PAHs) were measured in urban street dust with a view to understanding the potential risk to urban residents exposed to street dust, sources, and distribution of the PAHs. Gas chromatography–mass spectrometry was used to measure the concentrations of the PAHs after ultra-sonication with hexane/dichloromethane and clean up. The total concentrations of the ?16 PAHs in the urban street dust from Warri and its environs ranged from 165.1 to 1012 µg kg^?1. The isomeric ratios and the PCA indicated that combustion of petroleum and biomass are the major sources of PAHs in Warri and its environs. The total BaP carcinogenic and mutagenic potency concentrations (?BaP_TEQ and ?BaP_MEQ) were in the range of 0.03 to 219 µg kg^?1 and 0.52 to 182 µg kg^?1, respectively. The incremental life cancer risk from exposure of the residents of Warri and its environs ranged from 4.07 × 10^?7 to 3.11 × 10^?3 and 2.13 × 10^?7 to 1.49 × 10^?3 for the children and adults, respectively, which were higher than the baseline value of acceptable risk of 10^?6 (i.e., one case per million people).     

Degradation of dibenzothiophene by Brevibacterium sp.DO

Dibenzothiophene, a polycyclic aromatic sulfur heterocycle, represents as a model compound the organic sulfur integrated in the macromolecular coal matrix. A pure culture of a Brevibacterium species was isolated, which is able to use dibenzothiophene as sole source of carbon, sulfur and energy for growth. During dibenzothiophene utilization sulfite was released in a stoichiometrical amount and was further oxidized to sulfate. Three metabolites of dibenzothiophene degradation were isolated and identified as dibenzothiophene-5-oxide, dibenzothiophene-5-dioxide and benzoate by cochromatography, UV spectroscopy and gas chromatographymass spectrometry analyses. Based on the identified metabolites a pathway for the degradation of dibenzothiophene by Brevibacterium sp. DO is proposed.Non-standard abbreviations DBT dibenzothiophene - PASH polycyclic aromatic sulfur heterocycle - PAH polycyclic aromatic hydrocarbons - GC-MS gas chromatography-mass spectrometry - HPLC high pressure liquid chromatography - IC ion chromatography     

Residues of Aliphatic and Polycyclic Aromatic Hydrocarbons in Some Fish Species of Lake Temsah,Ismailia, Egypt: An Analytical Search for Hydrocarbon Sources and Exposure Bioindicators

Residues of aliphatic and polycyclic aromatic hydrocarbons (PAHs) were monitored in some fish species collected from Temsah Lake, near Ismailia, Egypt. Fish were selected to represent different feeding habits and ecological niches in the lake's ecosystem. Fish samples were extracted using organic solvents, and residues of aliphatic and PAHs were separated using column chromatography and detected using gas liquid chromatography. Fish species were Clupea sirm, Mugil sehli, Mugil capito, Morone labrax, and Sciasna sp. Clupea sirm, a surface feeder fish had the highest concentration of aliphatic hydrocarbons, 320 ± 54 ng g^?1, while Morone labrax, a predatory fish that live in the water column, had the highest concentration of PAHs, 315.87 ± 46 ng g^?1. Even-number aliphatic hydrocarbons were more frequently detected in all fish species in comparison to odd-number aliphatic hydrocarbons, suggesting a petrogenic origin of these compounds. Meanwhile, the pattern of PAHs detected in the present study suggested that they originate from atmospheric deposition rather than land-based runoff. Morone labrax fish and Clupea sirm fish were the most suitable candidate bioindicators of exposure to aliphatic hydrocarbons and PAHs through fish consumption of the five fish species examined in this study.     

Direct measurement of the glucuronide conjugate of 1-hydroxypyrene in human urine by using liquid chromatography with tandem mass spectrometry

To evaluate human exposure to polycyclic aromatic hydrocarbons (PAHs), we developed a rapid, simple and sensitive method for determining 1-hydroxypyrene-glucuronide (1-OHP-G) in human urine. To improve precision, a deuterated glucuronide was used as an internal standard. The method requires only 1 mL of urine. The urine was treated with a mixed-mode anion-exchange and reversed-phase solid-phase extraction cartridge (Oasis MAX). The analytes were analyzed with a C(18) reversed-phase column with a gradient elution, followed by tandem mass spectrometry with electrospray ionization in negative ion mode. The detection limit of 1-OHP-G (corresponding to a signal-to-noise ratio of 3) was 0.13 fmol/injection. Urinary concentrations of 1-OHP-G determined by this method were strongly correlated (r(2)=0.961) with concentrations of 1-hydroxypyrene by conventional HPLC with fluorescence detection.