Determination of trace PAHs in seawater and sediment pore-water by solid-phase microextraction (SPME) coupled with GC/MS

A fast and reliable method for the determination of trace PAHs (polynuclear aromatic hydrocarbons) in seawater by solid-phase microextraction (SPME) followed by gas chromatographic (GC) analysis has been developed. The SPME operational parameters have been optimized, and the effects of salinity and dissolved organic matter (DOM) on PAHs recoveries have been investigated. SPME measures only the portion of PAHs which are water soluble, and can be used to quantify PAH partition coefficient between water and DOM phases. The detection limits of the overall method for the measurement of sixteen PAHs range from 0.1 to 3.5 ng/g, and the precisions of individual PAH measurements range from 4% to 23% RSD. The average recovery for PAHs is 88.2±20.4%. The method has been applied to the determination of PAHs in seawater and sediment porewater samples collected in Jiaozhou Bay and Laizhou Bay in Shandong Peninsula, China. The overall levels of PAHs in these samples reflect moderate pollution compared to seawater samples reported elsewhere. The PAH distribution pattern shows that the soluble PAHs in seawater and porewater samples are dominated by naphthalenes and 3 ring PAHs. This is in direct contrast to those of the sediment samples reported earlier, in which both light and heavy PAHs are present at comparable concentrations. The absence of heavy PAHs in soluble forms (<0.1-3.5 ng/L) is indicative of the strong binding of these PAHs to the dissolved or solid matters and their low seawater solubility.     

A comparison of the performance of two chromatographic and three extraction techniques for the analysis of PAHS in sources of drinking water

The aim of this work is to establish a sensitive and reliable method for the analysis of the 16 priority Environmental Protection Agency-defined polycyclic aromatic hydrocarbons (PAHs) found in water samples. Gas chromatography (GC)-mass spectrometry (MS) and high-performance liquid chromatography (HPLC)-fluorescence detection (FLD)-UV techniques are optimized to obtain an adequate resolution of all compounds. Validation of the methods is carried out, and a good performance is observed for both techniques. The HPLC-FLD-UV technique is somewhat more sensitive than the GC-MS technique for the determination of PAHs; thus, the HPLC-FLD-UV method is used to follow up both the solid-phase extraction (SPE) analysis using cartridges and discs and the liquid-liquid extraction (LLE), which are also evaluated for the extraction of the PAHs. Low recoveries between 43% and 79% are obtained using SPE cartridges, and higher values are obtained using SPE discs (56-96%) and LLE (60-105%). Better results are obtained using the LLE technique, and, thus, analysis of real water samples is carried out using this technique. LODs between 0.6 and 21 ng/L and relative standard deviations less than 15% are obtained using a spiked water sample analyzed using the full LLE HPLC-FLD-UV method.     

Determining PAHs and PCBs in aqueous samples: finding and evaluating sources of error

This work describes the problems that occur during routine multi-step determinations of polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), which can be present at trace levels in water, and identifies sources of analyte losses at particular steps during the analytical procedure. PAH and PCB adsorption onto the walls of the container ranged from 0 to 70%. PAH and PCB recoveries of >70% were achieved during the LLE and SPE extraction steps. During the process of enriching the dichloromethane extract with PAHs and PCBs, based on the gentle evaporation of solvent, losses were <24% and <19%, respectively. Model experiments show that neither isolation of PAHs and PCBs (performed using either LLE or SPE) nor extract enrichment reduce the reliability of PAH and PCB determination. The steps that lead to the greatest loss of analyte are the ones that involve sampling, transport and storage of the water samples.     

Determination of Polycyclic Aromatic Hydrocarbons in Mangrove Sediments: Comparison of Two Internal Standard Surrogate Methods and Quality-Control Procedures

Two internal standard surrogate (ISS) methods, ISS-I (with m-terphenyl as a single ISS) and ISS-2 (using five deuterated PAHs as a multi-ISS), for the determination of polycyclic aromatic hydrocarbons (PAHs) in mangrove sediments were compared. The recovery percentages of 16 PAHs except naphthalene in HS-6 (a certified reference material) were high, ranging from 69.3 to 111.8% for ISS-1 and from 71.8 to 120.3% for the ISS-2 method. Similarly, the PAH recovery percentages in spiked mangrove sediments and clean sand were lower for ISS-I than for ISS-2, but both methods met the accurate acceptance criteria for PAH recoveries. The reproducibility (i.e. the method precision) between the two ISS methods was also comparable and satisfactory, with relative standard deviation values in most cases within 20% of the data variability. These results indicate that both ISS methods were acceptable for the determination of PAHs in mangrove sediments, despite the fact that the matrix of mangrove sediments may interfere with the PAH recovery efficiency.     

Analysis of 27 polycyclic aromatic hydrocarbons by matrix solid-phase dispersion and isotope dilution gas chromatography-mass spectrometry in sewage sludge from the Spanish area of Madrid

A method for the determination of 27 polycyclic aromatic hydrocarbons (PAHs) in sludge from wastewater treatment plants (WWTPs) located in urban, industrial or rural zones is presented. PAHs were extracted by matrix solid-phase dispersion (MSPD) assisted by sonication. Purification of extracts was carried out by solid-phase extraction with C(18) and PAHs were eluted with acetonitrile. PAHs were determined by isotope dilution gas chromatography with electron impact mass spectrometric detection in the selected ion-monitoring mode (GC-MS-SIM), using deuterated PAHs as internal standards. The limits of detection ranged from 0.03 ng/g for acenaphthylene to 0.45 ng/g for benzo[b]naphtho[2,1-d]thyophene. After optimization, the method was validated with a certified reference sludge. The proposed analytical method was applied to determine PAH levels in sewage sludge samples collected from 19 water treatment plants located in the province of Madrid (Spain). In most of the examined samples, phenanthrene was the main compound with a mean concentration of 1062 ng/g. PAHs were detected in all of the samples, with total concentrations between 390 and 6390 ng/g dry weight for the 27 PAHs analyzed and from 310 to 5120 ng/g dry weight for the sum of the 10 PAHs considered in the draft European Union directive.     

Static subcritical water extraction with simultaneous solid-phase extraction for determining polycyclic aromatic hydrocarbons on environmental solids

A rapid and very simple method for extracting polycyclic aromatic hydrocarbons (PAHs) from soils, sediments, and air particulate matter has been developed by coupling static subcritical water extraction with styrene-divinylbenzene (SDB-XC) extraction discs. Soil, water, and the SDB-XC disc are placed in a sealed extraction cell, heated to 250 degrees C for 15 to 60 min, cooled, and the PAHs recovered from the disc with acetone/methylene chloride. If the cells are mixed during heating, all PAHs with molecular weights from 128 to 276 are quantitatively (>90%) extracted and collected on the sorbent disc and are then recovered by shaking with acetone/methylene chloride. After water extraction, the sorbent discs can be stored in autosampler vials without loss of the PAHs, thus providing a convenient method of shipping PAH extracts from field sites to the analytical laboratory. The method gives good quantitative agreement with standard Soxhlet extraction, and with certified reference materials for PAH concentrations on soil, sediment (SRM 1944), and air particulate matter (SRM 1649a).     

Determination of polycyclic aromatic hydrocarbons in sediment using solid-phase microextraction with gas chromatography-mass spectrometry

Manual solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) is applied for the determination of polycyclic aromatic hydrocarbons (PAHs) from natural matrix through a distilled water medium. Seven of the 16 PAH standards (naphthalene, acenaphthene, fluorene, anthracene, fluoranthene, pyrene, benzo[a]anthracene) are spiked on a marine muddy sediment. The samples, containing PAHs in the range of 10-20 ppm, are then aged at room temperature more than 10 days before analysis. The influence of the matrix, SPME adsorption time, pH, salt content, and SPME adsorption temperature are investigated. The reproducibility of the technique is less than 13% (RDS) for the first 6 considered PAHs and 28% (RDS) for benzo(a)anthracene with a fiber containing a 100-micron poly dimethylsiloxane coating. Linearity extended in the range of 5-50 picograms for PAHs direct injection, 5-70 picograms for PAHs in water, and 1-170 picograms for PAHs in sediment. The detection limit is estimated less than 1 microgram/kg of dry sample for the first 6 considered PAHs in sediment and 1.5 micrograms/kg of dry sample for benzo(a)anthracene using the selected ion monitoring mode in GC-MS. The recoveries of the considered PAHs are evaluated.     

Analysis of polycyclic aromatic hydrocarbons in pine needles by gas chromatography-mass spectrometry: comparison of different extraction and clean-up procedures

Three extraction methodologies (Soxhlet, ultrasonic and pressurized liquid extraction) and several clean-up procedures (Florisil, silica and alumina in cartridges or glass column format) were tested and compared to extract 16 US Environmental Protection Agency (EPA) polycyclic aromatic hydrocarbons (PAHs) from Pinus pinea L. needles. Quantification was done by gas chromatography with mass spectrometry, by internal standard method using five deuterated PAH surrogate standards. Among the several extraction and clean-up procedures tested, ultrasonic extraction followed by alumina cartridge clean-up was the preferred method, yielding recoveries between 72 and 100% and limits of detection between 0.22 and 0.71 ng/g dry weight. The performance of the method was tested to determine PAHs in naturally contaminated samples.     

Ultrasonication extraction and gel permeation chromatography clean-up for the determination of polycyclic aromatic hydrocarbons in edible oil by an isotope dilution gas chromatography–mass spectrometry

An analytical method for the determination of US EPA priority pollutant 16 polycyclic aromatic hydrocarbons (PAHs) in edible oil was developed by an isotope dilution gas chromatography–mass spectrometry (GC–MS). Extraction was performed with ultrasonication mode using acetonitrile as solvent, and subsequent clean-up was applied using narrow gel permeation chromatographic column. Three deuterated PAHs surrogate standards were used as internal standards for quantification and analytical quality control. The limits of quantification (LOQs) were globally below 0.5 ng/g, the recoveries were in the range of 81–96%, and the relative standard deviations (RSDs) were lower than 20%. Further trueness assessment of the method was also verified through participation in international cocoa butter proficiency test (T0638) organised by the FAPAS with excellent results in 2008. The results obtained with the described method were satisfying (z ≤ 2). The method has been applied to determine PAH in real edible oil samples.     

Optimization and validation of HPLC-UV-DAD and HPLC-APCI-MS methodologies for the determination of selected PAHs in water samples

Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants resulting from emissions of a variety of sources including industrial combustion, discharge of fossil fuels, and residential heating. Because of their mutagenic and carcinogenic properties, the study of PAHs in environmental matrices is of great importance. In this work, the extraction of 9 out of the 16 PAH priority pollutants according to the U.S. Environmental Protection Agency is carried out through liquid-liquid extraction (LLE) and solid-phase extraction (SPE). The determination of PAHs is made by high-performance liquid chromatography with diode-array detection and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. Between the extraction techniques used, LLE is revealed to be efficient in the extraction of the higher molecular weight PAHs, though SPE is adequate for the extraction of all PAHs. In the real water samples analyzed, no PAH is detected under the analysis conditions used.     

Multifactorial optimization approach for the determination of polycyclic aromatic hydrocarbons in river sediments by gas chromatography-quadrupole ion trap selected ion storage mass spectrometry

A procedure for the determination of very low polycyclic aromatic hydrocarbons (PAHs) concentrations in sediment samples has been developed by gas chromatography-quadrupole ion trap mass spectrometry (GC-QIT MS) after extraction with dichloromethane and purification by using silica gel cleanup. Identification and quantification of analytes were based on the selected ion storage (SIS) strategy using deuterated PAHs as internal standards. In order to search out the main factors affecting the SIS mass spectrometry efficiency, four MS parameters, including target total ion count (TTIC), waveform amplitude (WA), transfer line (XLT) and ion trap temperatures (ITT) were subjected to a complete multifactorial design. The most relevant parameters obtained (TTIC and WA) were optimized by a rotatable and orthogonal composite design. Optimum values for these parameters were selected for the development of the method involving PAH determination in sediment samples. The optimized method exhibited a range of 111-760% higher signal-to-noise (S/N) ratios for PAHs in comparison with the method operated by the default conditions, demonstrating that the multifactorial optimization contributed to substantially improve the sensitivity of the GC-QIT MS determination. The accuracy of the method was verified by analyzing NWRI EC-3 certified reference material (Lake Ontario sediment). The selectivity, sensitivity (limits of quantification were in the range of 0.02-11.0 ng g(-1)), accuracy (recoveries >or=77%) and precision (RSD相似文献   

An experimental design approach to optimise the determination of polycyclic aromatic hydrocarbons from rainfall water using stir bar sorptive extraction and high performance liquid chromatography-fluorescence detection

Stir bar sorptive extraction (SBSE) followed by HPLC-fluorescence detection (FLD) was optimised for analysing 15 polycyclic aromatic hydrocarbons (PAHs) from water samples, especially rainfall water with low PAH content. The literature data described widely different experimental conditions for the extraction of PAHs by SBSE. A chemometric approach was therefore used to evaluate the statistically influential and/or interacting factors, among those described in the literature, and to find the best extraction and desorption conditions. Among six factors studied in a 2(6-2) fractional factorial design, only sample volume, extraction time and the interaction between both of them had significant effects on the PAH extraction recoveries. Optimal sample volume of 10 mL and extraction time of 140 min were obtained with a response surface design. For the desorption conditions, a Box-Behnken design showed that desorption time, temperature and PAH concentrations had significant effects. The best conditions were two successive desorptions with 100 microL of acetonitrile for 25 min at 50 degrees C. The optimised method was repeatable (RSD< or =5.3% for 50 ng L(-1) spiked water and < or =12.8% for 5 ng L(-1) spiked water), linear (R(2)> or =0.9956), with quantitative absolute recoveries (> or =87.8% for 50 ng L(-1) spiked water), and with the LOD between 0.2 and 1.5 ng L(-1). The optimised method was successfully applied to six-rainfall water samples collected in a suburban area. The total PAHs concentrations studied ranged from 31 to 105.1 ng L(-1). Seasonal variation was observed and on average three PAHs were at the highest concentrations (phenanthrene, fluoranthene and pyrene).     

Development of solid-phase microextraction to study dissolved organic matter—Polycyclic aromatic hydrocarbon interactions in aquatic environment

Solid-phase microextraction coupled with gas chromatography and mass spectrometry (SPME–GC–MS) was developed for the study of interactions between polycyclic aromatic hydrocarbons (PAHs) and dissolved organic matter (DOM). After the determination of the best conditions of extraction, the tool was applied to spiked water to calculate the dissolved organic carbon water distribution coefficient (K_DOC) in presence of different mixtures of PAHs and Aldrich humic acid. The use of deuterated naphthalene as internal standard for freely dissolved PAH quantification was shown to provide more accuracy than regular external calibration. For the first time, K_DOC values of 18 PAHs were calculated using data from SPME–GC–MS and fluorescence quenching; they were in agreement with the results of previous studies. Competition between PAHs, deuterated PAHs and DOM was demonstrated, pointing out the non-linearity of PAH–DOM interactions and the stronger interactions of light molecular weight PAHs (higher K_DOC values) in absence of high molecular weight PAHs.     

Determination of semivolatile organic compounds in environmental samples by gas chromatography/mass spectrometry after extraction by cyclic steam distillation

A method was developed for the multiple determination of semivolatile organic compounds found in groundwater, river water, seawater, sediment, and soil. Forty standard compounds were determined: n-alkenes, cycloalkanes, aromatic hydrocarbons, and polycyclic aromatic hydrocarbons. The compounds were isolated from water and soil samples by using an essential oil distillator (cyclic steam distillator) with hexane as a solvent. The extract was cleaned by using a silica gel cartridge with an acetone-hexane solution. The compounds were determined by using a gas chromatograph/mass spectrometer with 12 stable isotope-labeled compounds (surrogate compounds). The efficiencies of recoveries from water samples were 80.0-106% for groundwater, 80.1-106% for river water, and 81.2-103% for seawater. The relative standard deviation (RSD) values were 2.05-16.0% for groundwater, 3.22-16.6% for river water, and 4.45-16.0% for seawater. The efficiencies of recoveries from sediment and soil were 71.5-96.4% and 70.1-99.8%, respectively. RSD values ranged from 2.27 to 16.0% for sediment and from 2.12 to 15.1% for soil. Adjustment of recovery efficiencies of standard compounds by using surrogate compounds gave more accurate values. The present study proved that an essential oil distillator provides satisfactory results for multiple determinations of the semivolatile compounds in environmental waters, sediment, and soil.     

Determination of polycyclic aromatic hydrocarbons in marine sediments using a new ASE-SFE extraction technique

In order to determine PAHs in marine sediment samples by GC/MS(SIM) a new extraction approach of ASE-SFE was evaluated using combined accelerated solvent extraction (ASE, dynamic and static mode) and supercritical fluid extraction (SFE, dynamic mode) without further purification of the sample. The solvents used for ASE-SFE were methylene chloride and carbon dioxide. The recovery data, precision and accuracy of the whole method were evaluated statistically. The average recoveries of PAHs, based on deuterated internal standards were 77% for 2-3-ring PAHs, 85% for 4-ring PAHs, 88% for 5-ring PAHs and 97% for 6-ring PAHs. The extraction time required for the ASE-SFE technique was 30 min, which is longer than in the case of independent use of ASE and shorter compared to SFE. ASE-SFE recoveries of PAHs from SRM marine sediment are comparable for (2-3-ring, 4-ring PAHs) or higher (5-ring, 6-ring PAHs) than reported for the conventional extraction methods of ASE and SFE. Method detection limits of (MDL) were statistically estimated. MDL values obtained for 15 PAHs compounds vary between 0.06 ngg(-1) and 3.54 ngg(-1).     

全二维气相色谱-飞行时间质谱测定地下水中低环多环芳烃及其衍生物

建立了地下水中低环多环芳烃及其衍生物的全二维气相色谱-飞行时间质谱(GC×GC-TOF MS)检测方法。对比研究了液液萃取(LLE)和固相萃取(SPE)对地下水中低环多环芳烃及其衍生物的提取效率,优选液液萃取为前处理方法。在优化条件下,除1,2,3,4-四氢萘(r=0.987 2)和联苯(r=0.989 9)外,其它目标物在0.1~1 000μg/L范围内具有良好的线性关系,相关系数(r)均大于0.99。地下水的平均加标回收率为63.3%~111%,除喹啉的相对标准偏差(RSD,n=6)为24.9%外,其余目标物的RSD均小于9.5%,方法检出限在1.63~14.7 ng/L之间。该方法用于河北地区6个地下水样中低环多环芳烃及其衍生物的检测,4个样品有检出,最高浓度达353 ng/L。     

Determination of polycyclic aromatic hydrocarbons in marine sediments using a new ASE-SFE extraction technique

In order to determine PAHs in marine sediment samples by GC/MS(SIM) a new extraction approach of ASE-SFE was evaluated using combined accelerated solvent extraction (ASE, dynamic and static mode) and supercritical fluid extraction (SFE, dynamic mode) without further purification of the sample. The solvents used for ASE-SFE were methylene chloride and carbon dioxide. The recovery data, precision and accuracy of the whole method were evaluated statistically. The average recoveries of PAHs, based on deuterated internal standards were 77% for 2–3-ring PAHs, 85% for 4-ring PAHs, 88% for ¶5-ring PAHs and 97% for 6-ring PAHs. The extraction time required for the ASE-SFE technique was 30 min, which is longer than in the case of independent use of ASE and shorter compared to SFE. ASE-SFE recoveries of PAHs from SRM marine sediment are comparable for (2–3-ring, 4-ring PAHs) or higher (5-ring, 6-ring PAHs) than reported for the conventional extraction methods of ASE and SFE. Method detection limits of (MDL) were statistically estimated. MDL values obtained for 15 PAHs compounds vary between 0.06 ngg^?1 and 3.54 ngg^?1.     

Simultaneous multidetermination of residues of pesticides and polycyclic aromatic hydrocarbons in olive and olive-pomace oils by gas chromatography/tandem mass spectrometry

A multiresidue method for determining major pesticides and polycyclic aromatic hydrocarbons (PAHs) in olive oils in a single injection by use of gas chromatography/tandem mass spectrometry (GC-MS/MS) is proposed. Samples are previously extracted with an acetonitrile/n-hexane mixture and cleaned up by gel permeation chromatography. Electron ionization and chemical ionization allow pesticides and PAHs to be determined in a single analysis. The precision obtained was quite satisfactory (relative standard deviations ranged from 3 to 7.8%), and so were recoveries (84-110%). The linear relation was observed from 1 to 500 microg/kg for pesticides and 0.3 to 200 microg/kg for PAHs; also, the determination coefficient, R(2), was better than 0.995 in all instances. The proposed method was applied to the routine analysis of PAH and pesticide residues in virgin and refined olive oil and olive-pomace oil samples.     

Optimization of An On-Line Precolumn Preconcentration Method for the Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Water Samples (River and Sea Water)

Abstract

A new on-line precolumn preconcentration method for the determination of EPA priority pollutants (PAHs) in river and sea water has been developed. The retention time for each PAH in the precolumn has been determined for several percentages of organic solvent (acetonitrile) in the sample. This is very important because recoveries show a great dependence on this parameter.

The proposed procedure, combined with HPLC and spectrofluorimetric detection, reaches very low detection limits (subnanograms per liter) and it has been applied to river and sea water samples with good results.     

Determination of polycyclic aromatic hydrocarbons in waters by ultrasound-assisted emulsification-microextraction and gas chromatography-mass spectrometry

An ultrasound-assisted emulsification-microextraction (USAEME) procedure was developed for the extraction of US EPA 16 polycyclic aromatic hydrocarbons (PAHs) in 10 mL of water samples, with subsequent determination by gas chromatography-mass spectrometry (GC-MS). After determination of the most suitable solvent and solvent volume, several other parameters (i.e., extraction time, centrifugation time and ionic strength of the sample) were optimized using a 2³ factorial experimental design. Limits of detection ranged from 0.001 to 0.036 μg L⁻¹. The developed procedure was applied to fortified distilled water with different fortification levels (0.5, 2 and 5 μg L⁻¹). Recoveries were over 92% and relative standard deviations of the recoveries were below 8%. The efficiency of the USAEME was compared with traditional liquid-liquid extraction (LLE) and solid-phase extraction on real water samples (i.e., tap water, well water and surface (lake) water as well as domestic and industrial wastewaters). The USAEME showed comparable efficiencies especially with LLE. The developed USAEME was demonstrated to be robust, viable, simple, rapid and easy to use for the determination of PAHs in water samples by GC-MS.