Microextraction Of Polycyclic Aromatic Hydrocarbons Research Articles

In-tube solid-phase microextraction of polycyclic aromatic hydrocarbons from refinery water samples using UiO-66/polyacrylonitrile electrospun nanofibers followed by high-performance liquid chromatography-ultraviolet detection.

A simple and quick fiber-in-tube solid-phase microextraction (FIT-SPME) was introduced for the extraction and determination of nine polycyclic aromatic hydrocarbons followed by a high-performance liquid chromatography-ultraviolet detector in refinery water samples. For this purpose, a water-resistant metal-organic framework with a high surface area called UiO-66 has been applied in the form of an electrospun coating on stainless steel wires. After that, all the fibers were packed in the lumen of a stainless-steel tube to make the extraction phase. Both one variable at a time and experimental design methods have been used to optimize effective parameters on FIT-SPME. Under optimum conditions, the method demonstrated good linearity between 0.5 and 1000.0µg/L with a coefficient of determination greater than 0.9906. Furthermore, the limits of detection values ranged from 0.2 to 1.5µg/L. The intra-day and inter-day relative standard deviations were<8.4% and<9.7%, respectively. Lastly, the proposed method was applied to extract and determine analytes in four refinery water samples as well as surface water containing high total dissolved solids, and well waters where satisfactory results have been obtained.

Silver nanoparticle-functionalized melamine-formaldehyde aerogel for online in-tube solid-phase microextraction of polycyclic aromatic hydrocarbons followed by HPLC-DAD analysis

Based on the π-metal interaction between silver nanoparticles (AgNPs) and aromatic compounds, AgNPs were in-situ grown to melamine-formaldehyde (MF) aerogel for improving the extraction performance to polycyclic aromatic hydrocarbons (PAHs). The AgNPs/MF aerogel was regulated through varing the concentration of reactants, and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction. As a new extraction coating, the AgNPs/MF aerogel was coated to stainless-steel wires for in-tube solid-phase microextraction (IT-SPME). The extraction effects of MF aerogels before and after the modification of AgNPs were compared, and the AgNPs greatly improved the extraction ability for PAHs reaching to 166.4 %. Combining IT-SPME with high performance liquid chromatographic detection, an online analytical system was constructed. Furthermore, the sampling volume and rate, concentration of organic solvent, and desorption time were optimized factor by factor. The online analytical method with low detection limits (0.003–0.010 μg L−1) and efficient enrichment factors (1998–3237) for PAHs was established, which fastly detected trace level of PAHs in drinking and environmental water samples. Compared with other methods, the method was comparable or better in the detection limit and linear range, indicating prospective application of the AgNPs/MF aerogel for sample preparation.

Needle trap devices packed with an imine-based 2D COF: An innovative tool for the sampling of polycyclic aromatic hydrocarbons in air

This study introduces a new method for sampling and microextraction of polycyclic aromatic hydrocarbons (PAHs) in the air using needle trap devices (NTDs) packed with an imine-based covalent-organic framework (COF) as an adsorbent. The NTD was coupled with gas chromatography-flame ionization detection (GC-FID) for analytes’ separation and quantification. The COF adsorbent was synthesized using a solvothermal method at room temperature and packed inside a stainless-steel needle. The adsorbent was characterized using X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM-EDS) and Brunauer-Emmett-Teller (BET) analysis. The method was developed in the laboratory under various conditions and subsequently applied in the field to compare the results with those obtained using sampling and analytical method-NIOSH 5528. The desorption conditions and breakthrough volume (BtV) were optimized at recommended exposure limits concentration using response surface methodology (RSM) with a central composite design (CCD). Accordingly, the optimal values for desorption temperature and BtV were obtained 310 °C and 2840 mL, respectively. The limits of detection (LODs) and the limits of quantification (LOQs) were found to be 0.021–0.027 and 0.065–0.091 μg L−1, respectively. The repeatability and reproducibility of the method (R%) were estimated to be 4.02–6.83 % and 8.51–10.34 %, respectively. Also comparing the mean concentrations of the samples collected by the NTD and the NIOSH 5528 method, revealed no statistically significant differences between the methods (p > 0.05). Overall, the COF-packed NTD was identified as an appropriate and reliable method for sampling and extracting occupational and ambient contaminants in the workplace air.

A durable hydrophobicity hydrazone covalent organic framework coating for solid phase microextraction of polycyclic aromatic hydrocarbons in food and environmental sample

In this study, a durable hydrophobicity hydrazone covalent organic framework (BTCH-PTA-COF) has been developed as fiber coating, which was applied to solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The hydrophobic and π-π packing interactions between BTCH-PTA-COF and PAHs were confirmed by contact angle experiments and Van der Waals surface electrostatic potential analysis. Further, large specific surface area, good chemical and thermal stability have positive promoting effect on extraction. The method of wide linearity (0.25–300 µg·L−1), low detection limits (0.03–0.05 µg·L−1) and high enrichment factors (767–1411) for the detection of PAHs is explored, coupling BTCH-PTA-COF based SPME with gas chromatography with hydrogen flame detector (GC-FID). The relative standard deviations (RSDs) for inter-day and intra-day extractions of PAHs are ranging from 4.1 % to 9.6 % and 2.9 % to 6.4 %, respectively. The method successfully detected and quantified trace PAHs in tea beverages and river water samples with recoveries from 88.5 % to 104.8 %. The BTCH-PTA-COF coated fiber is ultra-stable in recycled extraction and reused at least 120 times, which could surpass published and commercial SPME fiber.

Nanoleaf-derived carbon materials as a sensitivity coating for solid‑phase microextraction of polycyclic aromatic hydrocarbons.

Metal-organic framework-derived carbon materials have shown extensive application in the sensitive extraction of polycyclic aromatic hydrocarbons (PAHs), but more active sites for its adsorption were still a tireless pursuit. In this study, ZIF-nanoleaf-derived carbon (NLCs) was synthesized and developed as a solid-phase microextraction (SPME) fiber (NLCs-F). The extraction performance was compared with ZIF-dodecahedron-derived carbon (DHCs) coated fiber (DHCs-F), which was prepared by only changing the ratio of the reactants. The unique morphology of NLCs provided abundant adsorption active sites for the selected PAHs, while the large average aperture facilitated selective extraction of high molecular weight analytes. Additionally, the high carbon content enhanced the strong enrichment capability for hydrophobic PAHs. Hence, the prepared NLCs-F coupled with GC-MS showed a good correlation coefficient (0.9975) in a wide linear range, low limits of detection (0.3-1.8ng L-1), satisfactory repeatability, and reproducibility, which made it apply in the enrichment of PAHs in actual tea and coffee samples.

Biochar nanosphere-functionalized carbon fibers for in-tube solid-phase microextraction of polycyclic aromatic hydrocarbons in environmental water followed by liquid chromatography and diode array detection.

In order to improve the extraction ability of carbon fibers (CFs) for microextraction ofpolycyclic aromatic hydrocarbons (PAHs), biochar nanospheres derived from glucose were in-situ grown onto the surface of CFs via hydrothermal synthesis. The surface morphology and elemental composition of biochar nanospheres-CFs were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. Thereafter, the biochar nanosphere-CFs were pulled into the polyetheretherketone tube for solid-phase microextraction, and the tube was combined with high-performance liquid chromatography-diode array detector to online detect PAHs. With the help of π-stacking, hydrophobic, and hydrophilic effect of biochar nanospheres, the extraction efficiency of CFs was greatly enhanced (enrichment factor increased by 293% compared with the original). The conditions affecting the analytical performance (sampling volume, sampling rate, methanol content, and desorption time) were investigated. Under the optimal conditions, an online analytical method for microextraction and determination ofseveral PAHs was developed, and satisfactory results were achieved. The limits of detection were 0.003-0.010 ng mL-1 owing to high enrichment effect (2973-3600), linearity ranged from 0.010-15.0 ng mL-1, andrelative standard deviations were 0.4%-1.6% (intra-day) and 2.4%-4.4% (inter-day), respectively. The method was applied toanalyze environmental water samples (rain water, snow water, and river water), and spiked recoveries within 80.0%-119% were obtained.

In-situ preparation of β-cyclodextrin-crosslinked polymer coated glass fiber for in-tube solid-phase microextraction of polycyclic aromatic hydrocarbons from water samples

Governments and organizations are paying increasing attention to the monitoring of polycyclic aromatic hydrocarbons (PAHs) in the environment. In this study, a β-cyclodextrin-based hyper-crosslinked polymer (β-CD-HCP) was prepared via the Friedel–Crafts reaction and used as a coating for an in-tube solid-phase microextraction (IT-SPME) glass fiber based on an in-situ preparation method. Subsequently, it was used for the analysis of six PAHs in water samples. The β-CD-HCP showed an excellent adsorption performance for the PAHs owing to its unique structural characteristics and multiple bonding forces (hydrophobic interaction, π–π, and electrostatic interactions) between the β-CD-HCP and PAHs. The adsorption mechanism of the β-CD to PAHs was investigated using density functional theory calculation experiments. By coupling high-performance liquid chromatography with a diode array detector, an online analysis method was established for the PAHs with a wide linear range (0.01–20 µg L–1), high enrichment factor (2130–2670), and low limits of detection (0.004–0.008 µg L–1). The PAHs in the water samples were successfully analyzed using this proposed online method with satisfactory recoveries in the range of 79.9–106.7% and relative standard deviations under 4.0%. The above results demonstrate that the prepared β-CD-HCP-based IT-SPME glass fiber has good application prospects for the pretreatment of PAHs in various aqueous environmental samples.

Covalent organic framework in situ grown on the metal-organic framework as fiber coating for solid-phase microextraction of polycyclic aromatic hydrocarbons in tea.

A novel MIL-88-NH2@COF composite was produced by in situ growth of covalent organic framework (COF) on the metal-organic framework (MOF) surface. To obtain a coating fiber for solid-phase microextraction (SPME), the MIL-88-NH2@COF composite physically adhered to the stainless steel wire. Combined with gas chromatography-flame ionization detection (GC-FID), various analytes such as chlorophenols (CPs), phthalates (PAEs), and polycyclic aromatic hydrocarbons (PAHs) were extracted and determined to evaluate the extraction performance of MIL-88-NH2@COF coated fibers and explore their extraction mechanism. This composite exhibit excellent extraction performance and adsorption capacity for various analytes, especially for PAHs with enrichment factor up to 9858. The SPME-GC-FID method based on MIL-88-NH2@COF fiber was established for the determination of five PAHs after the main extraction conditions were optimized. Under optimal conditions, the proposed technique showed a wide linear range (1-150ngmL-1) with a low limit of detection (0.019ngmL-1) and a high coefficient of determination (R2 > 0.99). The developed SPME-GC-FID method was used to determine PAHs in green tea and black tea samples, with good recoveries of 51.70-103.64% and 68.56-103.64%, respectively. It is worth mentioning that this is the first time MIL-88-NH2@COF composites have been prepared and applied to SPME. The preparation method of the composite provides a new idea in adsorbent preparation, which will contribute to the field of SPME.

In situ growth of porous organic framework on iron wire for microextraction of polycyclic aromatic hydrocarbons

In this work, a novel spherical metal organic framework (MOF) was first in situ grown on the surface of iron wire (IW), in which IW served as the substrate and metal source for MOF (type NH2-MIL88) growth without adding additional metal salts in the process, while spherical NH2-MIL88 provided more active sites for further construction of multifunctional composites. Subsequently, a covalent organic framework (COF) was covalently bonded to the surface of the NH2-MIL88 to obtain the IW@NH2-MIL88@COF fibers, which were used for headspace solid-phase microextraction (HS-SPME) of polycyclic aromatic hydrocarbons (PAHs) in milk samples prior to determination by gas chromatography-flame ionization detection (GC-FID). Compared with the fiber prepared by physical coating, the IW@NH2-MIL88@COF fiber prepared by in situ growth and covalent bonding exhibits better stability and possesses more uniform layer. The extraction mechanism of the IW@NH2-MIL88@COF fiber for PAHs was discussed, which mainly owed to π-π interactions and hydrophobic interactions. After optimization of the primary extraction conditions, the SPME-GC-FID method was established for five PAHs with a wide linear range (1–200 ng mL−1), good linearity coefficient (0.9935–0.9987) and low detection limits (0.017–0.028 ng mL−1). The relative recoveries for PAHs detection in milk samples ranged from 64.69 to 113.97%. This work not only provides new ideas for the in situ growth of other types of MOF, but also provides new methods for the construction of multifunctional composites.

Covalent Organic Framework/Reduced Graphene Oxide Composite for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons in Honey

Covalent Organic Framework/Reduced Graphene Oxide Composite for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons in Honey

The Preparation of Covalent Bonding COF-TpBD Coating in Arrayed Nanopores of Stainless Steel Fiber for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons in Water.

Covalent organic framework (COF)-TpBD was grafted on the arrayed nanopores of stainless steel fiber (SSF) with (3-aminopropyl) triethoxysilane as the cross-linking agent. The prepared SSF bonded with COF-TpBD showed high thermal and chemical stability and excellent repeatability. The prepared SSF bonded with COF-TpBD was also used for the solid-phase microextraction (SPME) of seven kinds of polycyclic aromatic hydrocarbons (PAHs) in actual water samples, followed by gas chromatography with flame ionization detection (GC-FID) determination, which exhibited low limits of detection (LODs), good relative standard deviation (RSD) and high recoveries.

Metal organic framework/covalent organic framework composite for solid-phase microextraction of polycyclic aromatic hydrocarbons in milk samples

Based on the excellent physicochemical properties of metal organic framework (MOF) and covalent organic framework (COF), a novel MOF/COF composite was designed and prepared as coating fiber for headspace solid-phase microextraction (HS-SPME). Based on the amino group on the surface of as-synthesized UiO-66-NH2, porphyrin-based COF was covalently grown on the MOF surface by using tetra(4-aminophenyl)porphyrin and 4,4′-biphenyldicarboxaldehyde as building blocks to fabricate a novel MOF/COF composite. Subsequently, the composite was physically coated on the surface of polished stainless-steel wire for HS-SPME of polycyclic aromatic hydrocarbons (PAHs) by gas chromatography-flame ionization detection (GC-FID) determination. The morphology and structure of the MOF/COF composite was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and N2 adsorption–desorption. Influential adsorption and desorption parameters were optimized and the extraction mechanism was also discussed. Under optimal conditions, an HS-SPME/GC-FID method based on MOF/COF composite coated fiber was established for the analysis of PAHs in milk samples. The linear ranges of this method were 0.2–50.0 ng mL−1 (R2 > 0.9908), and the limits of detection and quantitation were in the range of 0.02–0.07 ng mL−1 and 0.07–0.24 ng mL−1, respectively. The relative standard deviations (RSDs) for PAHs were all less than 7.05 %, which indicated eminent repeatability and reproducibility of the established method. Besides, the enrichment factors for PAHs were relatively high in the range of 2003 to 7763, and the recoveries for milk samples were ranged from 85.43 % to 115.8 % with satisfactory RSDs of 0.92–9.00 %.

Surfactant-enhanced air-agitation liquid-liquid microextraction of polycyclic aromatic hydrocarbons from edible oil using magnetic deep eutectic solvent prior to HPLC determination.

Herein, an air-agitation liquid-liquid microextraction procedure was developed for the extraction of several polycyclic aromatic hydrocarbons from edible oil samples. In this study, the extraction procedure was achieved using a new magnetic deep eutectic solvent as the extraction solvent, in which there was no need for centrifugation. To enhance the rate of extraction of the analytes from the samples, the method was promoted by the use of surfactant addition. The extracted analytes were determined by high-performance liquid chromatography with a diode array detector. The influence of various parameters on the extraction efficiency was studied by response surface methodology using a central composite design. Under optimal conditions, linear calibration curves for the target analytes were achieved in the range of 0.43-250 ng g-1. The limits of detection and quantification were in the ranges of 0.04-0.13 and 0.13-0.43 ng g-1, respectively. The repeatability of the method in terms of intra- and inter-day precision was ≤4.7% and ≤6.7%, respectively. The extraction recovery of the method ranged from 75 to 88%. The obtained results show that the proposed method is efficient for the analysis of the target analytes in various oil samples without obvious matrix effects. Pyrene was found in olive oil at a concentration of 42 ng g-1.

Carbonized MXene-polyvinylpyrrolidone as an adsorbent for solid-phase microextraction of polycyclic aromatic hydrocarbons from tea beverages prior to GC analysis

MXene-polyvinylpyrrolidone (MXene-PVP) was first prepared by physically doping combined with spray drying, which can overcome the aggregation of the MXene. Then, the MXene-PVP was carbonized to result in a carbonized MXene-PVP (MXene-PVP-C), which was then immobilized on stainless steel wire by sol–gel approach to prepare a new solid-phase microextraction (SPME) fiber. The prepared MXene-PVP-C coated fiber was studied for the extraction of 10 polycyclic aromatic hydrocarbons (PAHs) from tea beverages by using SPME method prior to gas chromatographic detection. The main SPME parameters, including extraction temperature, extraction time, salt concentration, sample solution pH and stirring rate, were investigated by central composite design methodology. Under the optimized conditions, the developed method gave the limits of detection of 0.03–0.15 µg/L, and the limits of quantification of 0.10–0.50 µg/L for the PAHs. The method recoveries for the PAHs in spiked tea beverages ranged from 78.6 % to 122 %. The single-fiber and fiber-to-fiber relative standard deviations were lower than 8.2 % and 9.6 %, respectively.

Sonochemical synthesis of deep eutectic solvent-coated magnetic nanoparticles and their application in magnetic dispersive micro solid phase extraction–dispersive liquid–liquid microextraction of polycyclic aromatic hydrocarbons from mascara

In this study, application of magnetic dispersive micro solid phase extraction of polycyclic aromatic hydrocarbons from mascara was reported. The extracted analytes were concentrated by a dispersive liquid–liquid microextraction procedure to reach high enrichment factors and low detection limits. In this work, deep eutectic solvent-coated iron nanoparticles were synthesized sonochemically and characterized by energy–dispersive X–ray spectroscopy, scanning electron microscopy, Furrier transform infrared spectrometry, and vibrating sample magnetometry. The extraction procedure was done by extracting the analytes from mascara into an aqueous solution composed of methanol and deionized water. Then the sorbent was added into the solution and the mixture was vortexed. After that the sorbent was separated from the aqueous solution and the analytes were desorbed by methanol with the aid of vortexing. Whole of the elution solvent was collected and mixed with carbon tetrachloride and dispersed into sodium chloride solution. Validation data showed that limits of detection and quantification were within the ranges of 0.33–0.57 and 1.1–1.9 ng/g, respectively. Relative standard deviation values were ≤ 8.6%. The extraction recovery values were in the range of 80–95%. The new method was successfully used for the analysis of the studied compounds in five mascara samples and three analytes were detected in all samples at ng/g level.

Silica Aerogel Hybridized with Melamine-Terephthalaldehyde Polymer for In-Tube Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons from Environment Water.

To improve the extraction performance of the silica aerogel, a melamine-terephthalaldehyde polymer was used to hybridize silica aerogel, and the hybridized aerogel was coated on the surface of stainless steel wire to prepare a fiber-filled extraction tube through placing four wires into a polyetheretherketone tube. The tube was combined with high-performance liquid chromatography, then the online extraction and detection were established. Several polycyclic aromatic hydrocarbons (PAHs) were selected as the target analytes. Under the optimum extraction and desorption conditions, the limit of detection was as low as 3.0 ng L−1, and the linear range was 0.01–20.0 μg L−1. The enrichment factors of PAHs were in the range of 1724–2393. Three environmental water samples of mineral water, tap water and river water were analyzed by this method, and the recoveries that spiked at 1.0–10.0 μg L−1 were between 80.5–126%. It showed many advantages compared with other methods, such as better sensitivity, faster detection and online analysis.

Binder-Free Decorated Cu Cluster-Based Metal-Organic Framework on Copper Film for Thin-Film Microextraction of Polycyclic Aromatic Hydrocarbons Followed by High-Performance Liquid Chromatography-Photo Diode Array Detection

The present study explains the in situ growth of Cu cluster-based metal-organic framework on copper substrate for thin film microextraction approach. Cu cluster-based metal-organic framework has been growth via a hydrothermal method on electrochemically anodized copper substrate. After thin film microextraction, some polycyclic aromatic hydrocarbons were quantified via high performance liquid chromatography- photo diode array detection. The influence of effective parameters such as extraction time, extraction temperature, agitator speed and ionic strength of the sample was investigated and the optimum conditions were chosen. Calibration curves were obtained in 0.0001–10 µgL−1 range with acceptable linearity as R2 > 0.986. The range of 1 and 3 pgL−1 was calculated as limits of detection, with the relative standard division below 5.1% in the optimal condition. For evaluating the model, samples from river water and wastewater were used and investigated. It was found that relative recoveries were between 96-104%. The proposed method provided a simple, efficient and environmental approach for the rapid and convenient determination of polycyclic aromatic hydrocarbons in real samples.

Hollow Fiber-Solid Phase Microextraction of Polycyclic Aromatic Hydrocarbons from Environment Water Followed by Flash Evaporation GC/MS

Hollow Fiber-Solid Phase Microextraction of Polycyclic Aromatic Hydrocarbons from Environment Water Followed by Flash Evaporation GC/MS

Hydrothermal in situ growth and application of a novel flower-like phosphorous-doped titanium oxide nanoflakes on titanium alloy substrate for enhanced solid-phase microextraction of polycyclic aromatic hydrocarbons in water samples

A novel flower-like phosphorous-doped titanium oxide nanocomposite coating was in situ grown on nickel-titanium alloy (NiTi) fiber by hydrothermal treatment in phosphoric acid solution. The experimental results demonstrated that phosphorous-doped titanium oxide nanoflakes (P-TiONFs) with an average thickness of 80 nm were formed on the NiTi fiber substrate in 0.1 mol L−1 H3PO4 at 150 °C for 6 h. Thereafter, the resulting P-TiONFs were used as SPME fiber coatings for the adsorption of typical aromatic analytes from environmental water samples, which were determined by HPLC-UV. These P-TiONFs exhibited good adsorption selectivity for hydrophobic PAHs. After optimizing microextraction conditions, linear responses were achieved in the ranges of 0.05–200 μg L−1 for the determination of PAHs with determination coefficients higher than 0.999. LODs (S/N = 3) ranged from 0.009 to 0.132 μg L−1, while LOQs (S/N = 10) ranged from 0.030 to 0.441 μg L−1. RSDs for intra-day and inter-day analyses with a single fiber varied from 4.46% to 5.56% and 5.14%–6.75%, respectively. The relative recoveries of 83.60%–119.0% were achieved for the determination of PAHs in real water samples spiked at the concentration levels of 5.0 μg L−1 and 10.0 μg L−1 with RSDs below 7.38%. In addition, the fibers exhibited no significant decrease in adsorption efficiency after being used 240 adsorption and desorption cycles. The proposed method was successfully applied to the selective enrichment and determination of target PAHs in different water samples.

Sponge-like porous manganese(II, III) oxide as a coating for solvent-assisted solid-phase microextraction of polycyclic aromatic hydrocarbons followed by gas chromatography-mass spectrometry

A nanostructure sponge-like porous manganese(II, III) oxide was synthesized and applied as a new fiber coating for solvent-assisted solid-phase microextraction. The synthesized material was characterized via Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and N2 adsorption/desorption techniques. To investigate the extraction performance of the prepared material, direct immersion solid-phase microextraction followed by gas chromatography-mass spectrometry was used for the determination of the selected polycyclic aromatic hydrocarbons in wastewater samples. Three polycyclic aromatic hydrocarbons including 1-methylnaphthalene, anthracene, and pyrene were selected as model analytes. To maximize the sensitivity of the method, key experimental factors affecting the extraction efficiency of the analytes such as ionic strength, extraction solvent, stirring rate, extraction temperature and time, and desorption temperature and time were optimized. The applicability of the new coating material for the extraction of the selected analytes from wastewater samples was evaluated. Under the optimum conditions, detection limits between 0.7 and 1.5 ng L−1 were obtained for the model analytes. The linear dynamic range was 5.0–3.0 × 103 ng L−1 for all the analytes. Relative standard deviations were between 2 and 11%. In the case of real sample analysis, the extraction recoveries of the analytes were obtained in the range of 77–111%.