Hydrocarbons In Aqueous Samples Research Articles

A magnetic solid phase extraction microfluidic chip coupled with gas chromatography-mass spectrometry for the determination of polycyclic aromatic hydrocarbons in aqueous samples

In this paper, we designed and manufactured a reliable magnetic solid phase extraction (MSPE) microfluidic chip for determination of polycyclic aromatic hydrocarbons (PAHs) in water combined with gas chromatography-mass spectrometry. Sample loading, washing and elution are implemented with microinjection pump and integrated on a single chip, which reduced manual operation. Magnets were used to fix octadecyl/phenyl bifunctional Fe3O4@SiO2 extractant to avoid the design of weir structure in extraction chamber. The whole microfluidic chip was simple and low cost. Based on the microfluidic chip extraction platform, the on-chip MSPE method for the determination of PAHs was optimized and established. The results showed that this method required only 2 mL of sample, 2 mg of extractant, and 50 μL of elution organic solvent for whole on-chip MSPE process, which was environmentally friendly and consistent with green chemistry. Method verification results were displayed which the linear range of five PAHs was between 1-100 ng/mL with good linearity (R2≥ 0.9985), and the detection limits (S/N = 3) were 0.08–0.26 ng/mL. The RSDs of intra-day precision (n=6) and inter-day precision (n=9) for PAHs were less than 6.1 % and 7.2 %, respectively. Enrichment factors were determined to be 31.3–37.7. The recoveries of river water, tap water, bottle water, waste water and urine at three spiked levels were in the range of 89.9% to 113.7% and the matrix effect values were between 83.8% to 109.6%. The extraction platform has the advantages of accurate analysis, simple design and cost-effective, which is conducive to the widespread use of microfluidic chips

Determination of polycyclic aromatic hydrocarbons in aqueous samples using recycled polystyrene for pipette tip-solid phase extraction followed by HPLC-FLD

ABSTRACT Expanded polystyrene is widely produced and used due to its properties and, recently, its ability to present π–π interactions has been described. Therefore, this work proposed to use recycled polystyrene for solid phase extraction of 12 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Recycled polystyrene films were formed and characterised by Fourier transform infrared spectroscopy, scanning electron microscopy and affinity experiments. A moderate interaction was found, which allowed its integration in pipette tip-solid phase extraction followed by HPLC-FLD analysis. The method presents limits of detection in the range of 0.05–0.14 ng mL−1 for 12 PAHs analytes, with a precision (expressed as relative standard deviation) <10%. The methodology was applied to tap water samples, and the results were compared to those obtained using the official methodology, with no statistically significant differences. The proposed method is efficient, fast and has a low consumption of organic solvent.

Determination of Polycyclic Aromatic Hydrocarbons by Coated Vial Solid-Phase Microextraction Followed by HPLC

In this study, a rapid and inexpensive method called coated vial solid-phase microextraction for determining the polycyclic aromatic hydrocarbons in aqueous samples was presented. In this method for the first time consists of a commercial 10 mL serum vial (penicillin flask) coated with mercaptopropyl moiety a thin layer of adsorbent immobilized on the inner surface of the vial. Extraction was started by adding 5 mL of the sample into the vial and shaking by hand. Then the washing and elution process was performed. To analysis the target compounds, high-performance liquid chromatography were used. The peaks are evaluated either by their area or height. In this study, the condition of polycyclic aromatic hydrocarbons extractions was optimized by varying the handshaking time, salt concentration, elution time, sample pH, type of elution solvent, and volume of elution solvent. The repeatabilities for one device, expressed as relative standard deviation, were 3.9%–5.8%. The limit of detections for the studied compounds were 0.01–0.03 µg L−1. Linear dynamic range of 0.0001–10 mg L−1 with good determination coefficients (R2) were in the range of 0.995–0.998 for polycyclic aromatic hydrocarbons. Extraction recoveries for different real samples were 97.3%–104.1%. Finally, the proposed method was applied for the analysis of polycyclic aromatic hydrocarbons in aqueous samples.

Deep eutectic solvent-based headspace single-drop microextraction of polycyclic aromatic hydrocarbons in aqueous samples

An improved deep eutectic solvent (DES)-based headspace single-drop microextraction procedure has been developed as a green procedure for gas chromatography-mass spectrometric analysis of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The stability of the micro-drop was significantly improved using a DES as an extraction phase and a bell-shaped tube as a supporter. These strategies helped to perform the extraction process in higher temperatures and stirring rates. Finally, the back-extraction of the analytes into a proper solvent that is compatible with the chromatography system was applied. The efficacy of the independent variables on the extraction efficiency was evaluated via chemometric methods in two steps. The best result was obtained with choline chloride-oxalic acid at the molar ratio of 1:2, a stirring speed of 2000 rpm for 10 min as well as a sample temperature of 50 °C and with ionic strength prepared by using a 10% (w/v) NaCl. The method indicated a good linearity for the analytes (R2≥0.9989). Under optimal conditions, the analytical signal was linear in the range of 0.01–50 μg L−1. Limit of detection (LOD) and limit of quantification (LOQ) were evaluated at the concentration levels of 0.003–0.012 and 0.009–0.049 μg L−1, respectively. Intraday and interday precision for all targeted compounds was less than 7.2% and 11.3%, respectively. Consequently, the proposed procedure was efficiently applied to extract and analyze the 16 target compounds in real aqueous samples representing satisfactory recoveries (94.40–105.98%).

A green dispersive liquid phase microextraction technique based on the solidification of switchable hydrophilic fatty acid for determination of polynuclear aromatic hydrocarbons in aqueous samples.

A green dispersive liquid phase microextraction approach based on the solidification of switchable hydrophilic fatty acid as an extraction phase has been developed for the determination of 16 priority polynuclear aromatic hydrocarbons (PAHs) in aqueous samples. In this study, the centrifugation step was omitted by the applying salting-out phenomenon. The influence of main variables on the efficiency of the procedure was studied by chemometric methods. Under optimal conditions, the completion time for extraction was less than 1 min, and the detector response was linear in the range of 0.1-250 μg L-1. Limit of detection and limit of quantitation were estimated as the concentration range of 0.01-0.14 μg L-1 and 0.03-0.47 μg L-1, respectively. The precision consists of repeatability and reproducibility, which were determined by calculating the relative standard deviation percent; their values were less than 7.2% and 10.5%, respectively. Applicability of the developed procedure was successfully evaluated for the analysis of PAHs in different water samples.

Hydrophobic deep eutectic solvents as “green” extraction media for polycyclic aromatic hydrocarbons in aqueous samples

The paper presents novel nonionic and hydrophobic deep eutectic solvents which were synthesized from natural compounds, i.e., thymol, ±camphor, decanoic and 10-undecylenic acids. Fundamental physicochemical properties of the synthesized deep eutectic solvents were determined, followed by their application as extractants in ultrasound-assisted dispersive liquid-liquid microextraction to isolate and enrich polycyclic aromatic hydrocarbons from aqueous samples characterized by a complex matrix. The final determination was carried out by gas chromatography-mass spectrometry. The most important extraction parameters were optimized and the procedure was validated. The developed procedure is characterized by low limits of detection and quantitation, equal to 0.0039–0.0098 μg/L and 0.012–0.029 μg/L, respectively, good precision (RSD <6.09%), analyte recovery ranging from 73.5 to 126.2%, and a wide linear range. The procedure was applied to analysis of industrial effluents from the production of bitumens before and after treatment by advanced oxidation processes. A total of 16 PAHs at concentrations ranging from 0.12 to 46.2 μg/L were identified and determined.

Barium Sulfate Nanoparticles as a Coating for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons in Aqueous Samples

Owing to the high toxicity of polycyclic aromatic hydrocarbons (PAHs) and their low content in the environment, the development of efficient analysis methods is very important. In this work, an extraction tube was developed through filling barium sulfate nanoparticle-coated basalt fibers (BFs) in a poly(ether ether ketone) (PEEK) tube. According to the characterization result by scanning electron microscopy, BFs were evenly covered with barium sulfate nanoparticles, and their diameter was about 11 µm. To sensitively determine PAHs, the extraction tube was connected to a high-performance liquid chromatography instrument with diode array detector for an online enrichment and detection method. By optimizing sampling volume, sampling rate, the content of methanol in sample and desorption time, the analysis method provided a wide linear range (0.30–20 µg L− 1) and high enrichment ratio (71–2095), and was useful for the efficient detection of PAHs in environmental aqueous samples.

Synthesis of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposites as an adsorbent for the fast determination of 16 priority polycyclic aromatic hydrocarbons in aqueous samples.

A novel adsorbent made of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposite was synthesized and applied to determine 16 priority polycyclic aromatic hydrocarbons by magnetic solid phase extraction in water samples. FTIR spectroscopy, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy consistently indicate that the synthesized adsorbents are made of core-shell nanoparticles well dispersed on the surface of graphene and carbon nanotubes. The major factors affecting the extraction efficiency, including the pH value of samples, the amount of adsorbent, adsorption time and desorption time, type and volume of desorption solvent, were systematically optimized. Under the optimum extraction conditions, a linear response was obtained for polycyclic aromatic hydrocarbons between concentrations of 10 and 500ng/L with the correlation coefficients ranging from 0.9958 to 0.9989, and the limits of detection (S/N=3) were between 0.1 and 3.0ng/L. Satisfactory results were also obtained when applying these magnetic graphene/carbon nanotubes/polydopamine hybrid nanocomposites to detect polycyclic aromatic hydrocarbons in several environmental aqueous samples.

Semi-automated salt-assisted liquid–liquid extraction coupled to high-performance liquid chromatography to determine three aromatic hydrocarbons in aqueous samples

In this study, a new device for semi-automated salt-assisted liquid–liquid extraction was designed and coupled with high-performance liquid chromatography (HPLC) to determine three aromatic hydrocarbons in aqueous samples. In order to evaluate the performance of the designed device, three aromatic hydrocarbons including 2-naphthol, naphthalene and anthracene were selected as model analytes. Sample solution, extraction solvent and salt solution using separate channels were transferred to a sample holder, respectively. These three components were mixed using a magnetic stirrer. After stirrer stopping, the aqueous and organic phases were separated and organic layer transferred to the injection loop of HPLC system. Optimization process was achieved using response surface methodology by Design-Expert software. A central composite design was used to optimize the main parameters including pH (A), stirrer time (B), organic solvent volume (C) and salt concentration (D). The limit of quantitation for 2-naphthol, naphthalene and anthracene was 15.0, 25.0 and 1.0 ng mL−1, respectively. Under the optimum conditions, obtained recoveries for three analytes were in the range of 76.0–96.2% with relative standard deviation less than 8.2%. The salt-assisted liquid–liquid extraction method using the proposed device has been successfully used for the analysis of real samples containing studied analytes in various matrices.

Dispersive liquid–liquid microextraction based on solidification of floating organic drop and fluorescence detection for the determination of nitrated polycyclic aromatic hydrocarbons in aqueous samples

In this study, a dispersive liquid–liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO) combined with molecular fluorescence detection was developed for the analysis of nitrated polycyclic aromatic hydrocarbons in environmental samples. Parameters affecting the efficiency of the extraction procedure were evaluated and optimized, including the nature of the dispersant agent, extractant and dispersant volumes, salt addition effect, and extraction time. Additionally, various strategies in the emulsion formation process were assayed. After optimization, the values obtained for limits of detection and quantification for 3-nitrofluoranthene were 2.3ngmL−1 and 5ngmL−1 respectively, and for 9-nitroanthracene 1.7ngmL−1 and 2.5ngmL−1. The recovery values ranged from 95% to 100% and the enrichment factor attained varied from 380 to 400-fold. The developed method was successfully applied to the analysis of lake water and drinking water samples. The results indicated that the proposed approach is a novel, sensitive, fast and reproducible methodology suitable for the analysis of traces of environmentally important nitrated polycyclic aromatic hydrocarbons in water samples.

Comparison of Stir Bar Sorptive Extraction (SBSE) and Solid Phase Microextraction (SPME) for the Analysis of Polycyclic Aromatic Hydrocarbons (PAH) in Complex Aqueous Soil Leachates

Stir bar sorptive extraction (SBSE) and solid phase microextraction (SPME) are well-established sample preparation methods for the analysis of polycyclic aromatic hydrocarbons in aqueous samples. However, complex matrices especially characterized by slurry particles and dissolved organic matter (DOM) can hamper the extraction of PAH with both SBSE and SPME and lead to different results. Thus, we produced aqueous eluates from PAH-contaminated soils differing in particle size distribution and organic matter content and determined the PAH concentration in the eluates with both SBSE and SPME. Furthermore, we tested the influence of filtration on the PAH analysis. The excess finding of PAH with SBSE compared to SPME ranged from −16.6 to 24.5 %. The differences increased after filtration. We found a strong positive correlation of the excess finding to the total organic carbon content (TOC) and a negative one to the pH value. The results indicate that SBSE is less affected by complex matrices than SPME.

Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography–mass spectrometry

In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography–mass spectrometry (GC–MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500–950. In order to have a comprehensive analysis, multivariate curve resolution-alternating least squares (MCR-ALS) as a second-order calibration algorithm was used for resolution, identification and quantification of the target PAHs in the presence of uncalibrated interferences. The regression coefficients and relative errors (REs, %) of calibration curves of the PAHs were in the satisfactory range of 0.9971–0.9999 and 1.17–6.59%, respectively. Furthermore, analytical figures of merit (AFOM) for univariate and second-order calibrations were obtained and compared. As an instance, the limit of detections (LODs) of target PAHs were in the range of 1.87–18.9 and 0.89–6.49ngmL−1 for univariate and second-order calibration, respectively. Finally, the proposed strategy was used for determination of target PAHs in real water samples (tap and hookah waters). The relative recoveries (RR) and the relative standard deviations (RSDs) were 68.4–109.80% and 2.15–6.93%, respectively. It was concluded that combination of multivariate chemometric methods with USAEME-GC–MS can be considered as a new insight for the analysis of target analytes in complex sample matrices.

Comparison of air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction for polycyclic aromatic hydrocarbons determination in hookah water.

In this work, two disperser-free microextraction methods, namely, air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction are compared for the determination of a number of polycyclic aromatic hydrocarbons in aqueous samples, followed by gas chromatography with flame ionization detection. The effects of various experimental parameters upon the extraction efficiencies of both methods are investigated. Under the optimal conditions, the enrichment factors and limits of detection were found to be in the ranges of 327-773 and 0.015-0.05 ng/mL for air-agitated liquid-liquid microextraction and 406-670 and 0.015-0.05 ng/mL for ultrasound-assisted emulsification microextraction, respectively. The linear dynamic ranges and extraction recoveries were obtained to be in the range of 0.05-120 ng/mL (R(2) ≥ 0.995) and 33-77% for air-agitated liquid-liquid microextraction and 0.05-110 ng/mL (R(2) ≥ 0.994) and 41-67% for ultrasound-assisted emulsification microextraction, respectively. To investigate this common view among some people that smoking hookah is healthy due to the passage of smoke through the hookah water, samples of both the hookah water and hookah smoke were analyzed.

Analysis of polycyclic aromatic hydrocarbons in aqueous samples by large volume injection gas chromatography–mass spectrometry using the through oven transfer adsorption desorption interface

A new procedure for the determination of 17 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples by large volume injection–gas chromatography–mass spectrometry (LVI–GC–MS) using the Through Oven Transfer Adsorption Desorption (TOTAD) interface with nitrogen for solvent elimination is developed and validated. Up to 75mL of aqueous samples were injected to be sure that good solvent elimination were achieved, although 500µL were sufficient to achieve the required sensitivity.The performance of the developed method can be considered good: the relative standard deviation (RSD), (n=3) was lower than 13.8% for all the target analytes, the concentration of each PAH being 0.25μgL−1, the limit of detection and limit of quantitation ranged from 21.5 to 211.0 ng L−1 and from 71.7 to 703.3ngL−1 respectively, and the correlation coefficients (R2) were all higher than 0.9764 in the 1–16μgL−1 range.

Purge-assisted headspace solid-phase microextraction combined with gas chromatography/mass spectrometry for the determination of trace nitrated polycyclic aromatic hydrocarbons in aqueous samples

This study describes a new procedure, namely, purge-assisted headspace solid phase microextraction combined with gas chromatography/negative ion chemical ionization mass spectrometry (PA/HS-SPME-GC/NICI-MS), which is used to determine seven nitrated polycyclic aromatic hydrocarbons (NPAHs) in aqueous samples. High extraction efficiency was obtained with PA/HS-SPME with polydimethylsiloxane (PDMS) fiber coating. A programmable temperature vaporizing (PTV) inlet was used in the desorption process. Selected ion monitoring (SIM) was used for quantitative and qualitative purposes. The linear range of detection of the proposed method was 5–5000pg/mL with coefficients of determination between 0.995 and 0.999. Limits of detection (LODs) for seven NPAHs were 0.01–0.06pg/mL. The relative standard deviation was below 12.7% at a concentration of 50pg/mL. Compared with headspace-solid phase microextraction (HS-SPME), the purge procedure enhanced the extraction efficiency for high boiling point analytes, such as 7-nitrobenz[a]anthracene (7-NBA) and 6-nitrochrysene (6-NC). The proposed method provides a sensitive method for NPAH analysis at the pg/mL level. The application of the proposed method for the determination of trace NPAHs in real samples was investigated by analyzing aqueous samples from rivers. The concentrations of NPAHs detected from the samples ranged from 5.2 to 7.5pg/mL. This method was applied successfully in the analysis of trace NPAHs in river samples.

Triphenylamine-functionalized magnetic microparticles as a new adsorbent coupled with high performance liquid chromatography for the analysis of trace polycyclic aromatic hydrocarbons in aqueous samples

Triphenylamine (TPA)-functionalized magnetic microspheres (Fe(3)O(4)/SiO(2)/TPA) were prepared and applied as solid phase extraction (SPE) adsorbents for the analysis of polycyclic aromatic hydrocarbons (PAHs) in environmental samples in combination with high-performance liquid chromatography (HPLC). The magnetic solid-phase extraction (MSPE) conditions affecting the extraction efficiency were optimized, including elution solvent, standing time, amount of sorbent, and salt concentration. Due to the strong π-π conjugate effect between the benzene rings of TPA and PAHs, high extraction efficiency was achieved with spiked recoveries of 80.21-108.33% and relative standard deviations (RSD) of less than 10%. Good linearities (R(2) > 0.997) for all calibration curves were obtained with low limits of detection (LOD) of 0.25, 0.5, 0.5, 3.75, 0.2 and 0.04 ng L(-1) for anthracene, fluoranthene, pyrene, chrysene, benzo[b]fluoranthene and benzo[k]fluoranthene, respectively. The achieved results indicate the applicability of Fe(3)O(4)/SiO(2)/TPA as MSPE adsorbents.

A novel dispersive liquid–liquid microextraction based on solidification of floating organic droplet method for determination of polycyclic aromatic hydrocarbons in aqueous samples

A new dispersive liquid–liquid microextraction based on solidification of floating organic droplet method (DLLME-SFO) was developed for the determination of five kinds of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. In this method, no specific holder, such as the needle tip of microsyringe and the hollow fiber, is required for supporting the organic microdrop due to the using of organic solvent with low density and proper melting point. Furthermore, the extractant droplet can be collected easily by solidifying it in the lower temperature. 1-Dodecanol was chosen as extraction solvent in this work. A series of parameters that influence extraction were investigated systematically. Under optimal conditions, enrichment factors (EFs) for PAHs were in the range of 88–118. The limit of detections (LODs) for naphthalene, diphenyl, acenaphthene, anthracene and fluoranthene were 0.045, 0.86, 0.071, 1.1 and 0.66 ng mL −1, respectively. Good reproducibility and recovery of the method were also obtained. Compared with the traditional liquid-phase microextraction (LPME) and dispersive liquid–liquid microextraction (DLLME) methods, the proposed method obtained about 2 times higher enrichment factor than those in LPME. Moreover, the solidification of floating organic solvent facilitated the phase transfer. And most importantly, it avoided using high-density and toxic solvent in the traditional DLLME method. The proposed method was successfully applied to determinate PAHs in the environmental water samples. The simple and low-cost method provides an alternative method for the analysis of non-polar compounds in complex environmental water.

Total concentration analysis of polycylic aromatic hydrocarbons in aqueous samples with high suspended particulate matter content

The European water framework directive (WFD) requires priority pollutants to be measured in the whole water sample and not only in the dissolved phase. However, it does not give clear definitions on how to achieve this. To overcome this limitation, a new methodology of sample preparation procedure for the analysis of polycyclic aromatic hydrocarbons on the basis of extraction disks is introduced here. The automatable procedure includes a “one-step” extraction of the analytes both dissolved in the liquid phase of the sample and sorbed to suspended particulate matter. The latter is extracted concurrently with the solid-phase extraction (SPE) material within the elution step of the procedure. Separation, identification, and quantification of the analytes is performed by GC–MS. Results from surface water samples spiked with certified sediment up to 1000 mg/l are presented in this work and compared with results derived from liquid–liquid extraction (LLE). Most measured values are within or at least near certified uncertainty limits of the sediment. The SPE disk method shows much higher recoveries and better precision (relative standard deviations between 2% and 11%) than the standard LLE method. For all substances under investigation, the limits of quantification achieved range between 0.001 and 0.005 μg/l.

Magnetic solid-phase extraction based on octadecyl functionalization of monodisperse magnetic ferrite microspheres for the determination of polycyclic aromatic hydrocarbons in aqueous samples coupled with gas chromatography–mass spectrometry

Monodisperse magnetic C 18 microspheres were prepared based on the three-step reactions of solvothermal reduction, silanization and alkylation. The microspheres are of uniform sizes in the range of 200–260 nm. The structure of synthesized magnetic C 18 microspheres was studied by transmission electron microscopy, scanning electron microscopy, X-ray diffraction patterns, element analysis and vibrating sample magnetometry. This material has a high magnetic saturation value of 59 emu g −1 and is easy to manipulate under a magnet. The prepared material was used for the preconcentration of the polycyclic aromatic hydrocarbon in water. The effects of desorption solvent and the amount of adsorbent on the preconcentration were also investigated. The results showed that the developed method was beneficial for the preconcentration of PAHs of middle molecular weight.

Comparison of thin-film microextraction and stir bar sorptive extraction for the analysis of polycyclic aromatic hydrocarbons in aqueous samples with controlled agitation conditions

The characterization of a poly(dimethylsiloxane) (PDMS) thin film for active extraction of some polycyclic aromatic hydrocarbons was investigated in both a 1-L aqueous solution and a flow-through system. The thin film was attached to an electric bench-drill at a constant rotation speed for constant agitation and fast extraction. The performance of a PDMS-coated stir bar at a constant stirring speed was also investigated. The comparison showed that the extraction rate was much higher when using the thin film than the stir bar, and that the equilibration time was greatly shortened due to the larger surface area/volume ratio of the thin film. The extraction rate was roughly proportional to surface area of the extraction phase during the initial stage of the extraction process; the amount of analyte extracted was proportional to the ratio of the extraction phase between the thin film and the stir bar. Different agitation and stirring rates of the thin film and stir bar were applied for extraction, revealing that extraction efficiency can be improved by increasing rotation rate. The application of rotated thin film in the field proved it is a valid and easily operated method for the determination of polycyclic aromatic hydrocarbons (PAHs) in a campus river. However, the stir bar is not as convenient as a thin film in field sampling.