novel palm fatty acid functionalized magnetite

771

Journal of Oleo ScienceCopyright ©2017 by Japan Oil Chemists’ Societydoi : 10.5650/jos.ess17016J. Oleo Sci. 66, (7) 771-784 (2017)

Novel Palm Fatty Acid Functionalized Magnetite Nanoparticles for Magnetic Solid-Phase Extraction of Trace Polycyclic Aromatic Hydrocarbons from Environmental SamplesSiti Khalijah Mahmad Rozi1, 3, Hamid Rashidi Nodeh1, Muhammad Afzal Kamboh4, Ninie Suhana Abdul Manan1, 2 and Sharifah Mohamad1, 2,＊

1 Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, MALAYSIA2 University of Malaya Centre for Ionic Liquids, University of Malaya, 50603 Kuala Lumpur, MALAYSIA3 School of Bioprocess Engineering, University of Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis, MALAYSIA4 Department of Chemistry, Shaheed Benazir Bhutto University, Shaheed Benazirabad, Sindh, PAKISTAN

1 IntroductionPolycyclic aromatic hydrocarbons（PAHs）originate

mainly from incomplete combustion of organic matters（e.g. wood, coal, garbage, tobacco and oil）1, 2）. During recent decades, PAHs have come into attention as a significant of pollutant contaminating our environment. The level of PAHs present in our environment depends on their compo-sition, type and the degree of industrial pollution. PAHs are noxious, persistent and lipophilic in the environment3, 4）. Thus, they have high tendency to enrich in the food chain. PAHs are classified as carcinogenic, toxic and mutagenic,

＊Correspondence to: Sharifah Mohamad, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, MALAYSIAE-mail: [email protected] March 14, 2017 (received for review January 25, 2017)Journal of Oleo Science ISSN 1345-8957 print / ISSN 1347-3352 onlinehttp://www.jstage.jst.go.jp/browse/jos/　　http://mc.manusriptcentral.com/jjocs

therefore, they are hazardous to the ecology and can cause a severe health hazard to human, mainly cancer5）. Hence, the detection of PAHs from the environment has attracted worldwide concerns.

Since PAHs represent an emerging class of pollutants, it become necessary to develop a simple sample preparation technique to detect the trace residue in environmental ma-trices. There are numerous techniques for sample prepara-tion that have been reported to isolate PAHs from complex matrices prior to instrumental analysis, including cloud point extraction（CPE）6）, solid-phase micro extraction

Abstract: A novel adsorbent, palm fatty acid coated magnetic Fe3O4 nanoparticles (MNP-FA) was successfully synthesized with immobilization of the palm fatty acid onto the surface of MNPs. The successful synthesis of MNP-FA was further confirmed by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Energy dispersive X-Ray spectroscopy (EDX) analyses and water contact angle (WCA) measurement. This newly synthesized MNP-FA was applied as magnetic solid phase extraction (MSPE) adsorbent for the enrichment of polycyclic aromatic hydrocarbons (PAHs), namely fluoranthene (FLT), pyrene (Pyr), chrysene (Cry) and benzo(a)pyrene (BaP) from environmental samples prior to High Performance Liquid Chromatography- Diode Array Detector (HPLC- DAD) analysis. The MSPE method was optimized by several parameters such as amount of sorbent, desorption solvent, volume of desorption solvent, extraction time, desorption time, pH and sample volume. Under the optimized conditions, MSPE method provided a low detection limit (LOD) for FLT, Pyr, Cry and BaP in the range of 0.01-0.05 ng mL–1. The PAHs recoveries of the spiked leachate samples ranged from 98.5% to 113.8% with the RSDs (n = 5) ranging from 3.5% to 12.2%, while for the spiked sludge samples, the recoveries ranged from 81.1% to 119.3% with the RSDs (n = 5) ranging from 3.1% to 13.6%. The recyclability study revealed that MNP-FA has excellent reusability up to five times. Chromatrographic analysis demonstrated the suitability of MNP-FA as MSPE adsorbent for the efficient extraction of PAHs from environmental samples.

Key words: polycyclic aromatic hydrocarbons, magnetic solid phase extraction, palm fatty acid, magnetic nanoparticles

S. K. M. Rozi, H. R. Nodeh and M. A. Kamboh et al.

J. Oleo Sci. 66, (7) 771-784 (2017)

772

（SPME）7）, stir rod sorptive extraction（SRSE）8）, micro-sol-id phase extraction（μ-SPE）9）, dispersive liquid-liquid micro extraction combined micro solid phase extraction（DLLME/ μ-SPE）10）and solid-phase extraction（SPE）11, 12）. Among these, SPE is the most commonly used technique to pre-concentrate PAHs from environmental samples as this pro-cedure requires only a small amount of organic solvents and the adsorbent can be recovered satisfactorily after-wards. However, this method is time and labour intensive especially when it involves a large volume of sample13）. Hence, a rapid and simple SPE method for the extraction of PAHs from environmental samples is desirable.

In order to address these limitations, a new mode of SPE, magnetic solid phase extraction（MSPE）has gained a great consideration14）to isolate PAHs from complex matri-ces. This technique is based on the use of magnetic nanoparticles15, 16）which promises rapid extraction ability and excellent extraction efficiency17－19）. Rapid separation of the analyte of interest from interference can be achieved by applying an external magnet to recover the saturated adsorbent. Currently, magnetite（Fe3O4）nanoparticles（MNPs）are widely used as a MSPE sorbent due to its su-perparamagnetic property20）, high surface area available for reaction, effective contact, and good uptake capacity21, 22）. Furthermore, the surface of MNP can be easily functional-ized to achieve selective sample extraction. For example, hydrophobic layers such as n-octadecylphosphonic acid（OPA）23）, carbon24）, octadecyl（C18）25）, triphenylamine（TPA）26）, graphene14）, polymers27）and surfactants28）can be used to modify the surface of MNPs to enhance the selec-tivity of MSPE sorbent towards organic pollutants in envi-ronmental samples. However, preparations of the reported modified sorbents are tedious, time consuming and usually involve toxic reagents. Therefore, a novel magnetic adsor-bent which is simple, eco-friendly, cost effective, and has a high selectivity towards organic pollutants is highly desir-able in environmental analysis.

Fats and oil can be used as economical and eco-friendly hydrophobizing agents in modifying the surface of MNPs, turning it into a new highly hydrophobic MSPE adsorbent for the detection of lipophilic PAHs from the environmental samples. Herein, we highlight the facile synthesis of palm fatty acid functionalized magnetic nanoparticles（MNP-FA）as a new MSPE adsorbent for the extraction of PAHs from leachate and sludge samples. The presence of long alkyl chain in the mixture fatty acids; mainly C16 and C18 in palm olein, endowed the developed adsorbent with high extraction capabilities. This is because the hydrophobic alkyl chains can strongly interact with the organic PAHs pollutant in environmental samples. Additionally, this fabri-cated MSPE adsorbent showed a high resistance in corro-sive media, suggesting the ability of this adsorbent to work in harsh environments.

2 Experimental section2.1 Chemicals and reagents

Iron（II）chloride tetrahydrate, iron（III）chloride hexahy-drate（Sigma Aldrich）. N, N-dimetylformamide（DMF）, （3-aminopropyl）triethoxysilane（APTES）, aqueous ammonia, ethanol, ethyl acetate, acetonitrile, hydrochloric acid, potassium hydroxide（KOH）, anhydrous sodium sul-phate and hexane were purchased from Merck. PAHs stan-dards, fluoranthene（FLT）, pyrene（Pyr）, chrysene（Cry）and benzo（a）pyrene（BaP）were obtained Supelco. The stock solutions were prepared in methanol at a concentra-tion of 100 mg L－1. All stock solutions were kept at 4℃ in the dark.

Palm olein was purchased from supermarket in Bangsar, Kuala Lumpur. Palm fatty acid was obtained from the hy-drolysis of triacylglyceride（TAG）from palm olein. The fatty acid profile was analyzed and is shown in Table S1. The gas-liquid chromatography reference standard for fatty acid methyl esters was bought from Supelco.

2.2 InstrumentsThe functional groups of the nanoparticles were first

characterized using a FT-IR spectrometer（Spectrum 400 PerkinElmer）with a diamond ATR accessory, absorption mode with 4 scans at a resolution of ±4 cm－1, and a wave-number range of 4000 to 450 cm－1. Wettability analyses were performed using the TL 100 and TL101 contact angle measurement instruments. The particle size and morphol-ogy were investigated by JEOL JEM-2100F transmission electron microscope（TEM）. EDX analysis was performed using scanning electronic microscopy（SEM HITACHI SU8220, OXFORD Instruments）equipped with an energy dispersive X-ray spectrometry. The crystal phase of the prepared nanoparticles was determined using a PANana-lytical EMPYREAN X-ray powder diffraction（XRD）diffrac-tometer（CuK, radiation, λ＝1.541874 nm）, at a scanning speed of 0.07° / min from 15° to 75°（2θ）. The fatty acid methyl esters were prepared from palm fatty acid using an acid catalyst（sulphuric acid method）29）. The fatty acid composition was analyzed using a Shimadzu 2010 gas chro-matograph（Shimadzu, Kyoto, Japan）equipped with a split/splitless injector and a flame ionization detector（FID）. A BPX50 capillary column（SGE Analytical Science, Austra-lia）（30 m×0.25 mm i.d. 0.25 μm film thickness）was applied for the separation of fatty acids. Helium（with 99.999％ purity）was the carrier gas and is fed at a constant flow rate of 59.2 mL min－1. The injection port was operated using split mode. The detector temperature was set at 260℃, injector temperature was set at 139℃, and the oven temperature was initially set at 139℃ for 2 min, then in-creased by 8℃ min－1 up to 165℃, then 3℃ min－1 up to 192℃, 13.7℃ min－1 up to 240℃ and, finally for 11℃ min－1 at 240℃.

Novel Palm Fatty Acid Functionalized Magnetite Nanoparticles

J. Oleo Sci. 66, (7) 771-784 (2017)

773

2.3 Preparation of newly adsorbent（MNP-FA）2.3.1 Hydrolysis of palm olein

Hydrolysis of palm olein（Fig. 1A）as stated in literature30）

was applied to obtain palm fatty acid. Typically, 50 g of palm olein and 300 mL of 1.75 M of ethanolic KOH were heated at 65℃ for 2 hours. The unsaponifiable products were extracted by 100 mL of hexane and then discarded. The obtained mixture was mixed with deionized water and acidified with 100 mL 6 N hydrochloric acid until the solu-tion turned acidic（pH 1）. The extraction of fatty acids was repeated three times by using 100 mL of hexane for each extraction. The extraction product, a fatty acids-hexane mixture was washed with deionized water and dried with anhydrous sodium sulphate. The solvent was removed by rotary evaporator at 35℃ to obtain the palm fatty acid.2.3.2 Synthesis of MNPs

The procedure for the preparation of the MNPs is shown in Fig. 1B. The magnetite nanoparticles（MNPs）were syn-thesized using a chemical co-precipitation method31）. Briefly, 3.1736 g of FeCl2.4H20 and 7.5709 g FeCl3.6H2O were dissolved in 320 mL deionized water. The mixed solu-tion was then stirred under nitrogen at 80℃ for 1 hour. Then, 40 mL of aqueous ammonia was added into the reac-tion mixture rapidly. The resulting mixture was stirred under nitrogen for another 1 hour and then cooled to room temperature. The precipitated magnetic particles were washed five times with hot water until the filtrate becomes neutral and separated by magnetic decantation.2.3.3 Synthesis of MNP-APTES

MNP-APTES was prepared via a reported method32）

（Fig. 1C）. In this synthesis, hydrolyzed APTES was added to 100 ml magnetite fluid in a 250 ml round bottom flask. The mixture was stirred for 5 hours at 60℃ under nitrogen protection. After the solution was cooled to room tempera-ture, the resulting brownish product was separated by an external magnet and washed with ethanol and deionized water respectively several times. The final product was then dried in the vacuum at 70℃ for 24 hours.2.3.4 Synthesis of MNP-FA

Figure 1D illustrates the preparation route of MNP-FA. Freshly prepared 1.000 g MNP-APTES was dispersed in 10 ml of DMF, followed by the addition of 2.000 g palm fatty acid. The reaction mixture was stirred overnight at 60℃ under nitrogen protection. Then, the solution was cooled to room temperature and the obtained brownish product（MNP-FA）was magnetically collected. The obtained MNP-FA was washed repeatedly with excess ethanol and deionized water respectively and finally vacuum dried at 70℃ for 24 hours.

2.4 MSPE experiment15 mg of MNP-FA was placed in a vial. Then 30 mL of

the prepared spiked PAHs solution was transferred into the same vial. The solution was shaken for 15 minutes. The ad-

sorbent was isolated from the sample solution using an ex-ternal magnet and the sample solution was then decanted. The adsorbed PAHs on MNP-FA were eluted by shaking with 2.0 mL of desorption solvent（hexane）for 10 minutes. The collected eluate was dried under a flow of nitrogen gas and then dissolved in 0.5 mL acetonitrile. Finally, 10 μL of the eluate was injected into the HPLC system for analysis. The schematic process of MSPE method is shown in Fig. 2.

2.5 Real sample pre-treatmentLeachate and sludge samples were collected from a

landfill in Jeram, Kuala Selangor and were chosen as repre-sentatives of real samples in this study. The leachate samples were filtered through a 0.22 μm membrane and stored at 4℃ prior to use. 30 mL of the filtered leachate are used in each MSPE run.

The sludge samples were dried at room temperature, pulverized, and passed through a 1 mm sieve. Then, ultra-sound-assisted extractions（UAE）of the sludge samples were performed. Briefly, 1.00 g of the sludge sample was mixed with 3 mL of methanol in a 50-mL centrifuge tube and then sonicated for 10 min. The mixed sludge solution was centrifuged at 3500 rpm for 5 min and the supernatant was filtered through a PTFE syringe filter（13 mm, 0.22μm pore size）into a sample vial33）. The total volume of sample in the vial was then made up to 30 mL with distilled water. The sample are then used in MSPE as described previously in Section 2.4.

2.6 Liquid chromatographic conditionPAHs were separated and quantified using a high perfor-

mance liquid chromatography（HPLC）system which con-sisted of a Shimadzu（Tokyo, Japan）LC-20AT pump, SPD-M20A diode array detector, SIL-20A HT auto sampler, and CTO-10AS VP column oven. The separation was conducted using a C-18 reverse phase column（250 mm×4.6 mm; par-ticle size 5 μm）hypersil gold, Thermo science USA. The mobile phase was acetonitrile-water（80:20, v/v）at a flow rate of 1.0 mL min－1. The injection volume was 10 μL. The detections were set as follows: 6.77 min, 284 nm（for FLT）; 7.22 min, 270 nm（for Pyr）; 8.03 min, 266 nm（for Cry）; and 10.82 min, 266 nm（for BaP）.

3 Results and discussion3.1 Characterizations of the newly MNP-FA3.1.1 FT-IR spectra

In order to examine the functional groups of the synthe-sized MNPs, MNP-APTES and MNP-FA, all FT-IR spectra were recorded and are shown in Fig. 3A. In the FTIR spec-trum of MNPs, the peak at 537 cm－1 represents the vibra-tion of the Fe-O band34）. The two absorption peaks at 3400 and 1604 cm－1 correspond to the stretching and bending


J. Oleo Sci. 66, (7) 771-784 (2017)

774

Fig. 1　 The preparation scheme of（A）Palm fatty acid（B）MNPs（C）MNP-APTES and（D）MNP-FA（R ＝ the alkyl chain of the palm fatty acid）.


J. Oleo Sci. 66, (7) 771-784 (2017)

775

of the O-H group on the surface of MNPs35）. The new peak at 981 cm－1 for MNP-APTES is attributed to the Si-O group from APTES confirming the presence of silane on the surface of MNPs. The bands at 3411 cm－1 and 1603 cm－1 are attributed to N-H stretching vibration and the NH2 group, respectively14）. The intense peak at 1626 cm－1 is as-sociated with C＝O stretching. In addition, new bands ap-peared at 2921 and 2853 cm－1 are assigned to the asym-

metric and symmetric CH2 stretching, respectively. The new bands indicated that palm fatty acid has been success-fully functionalized onto the surface of MNP-APTES.3.1.2 Crystal phase analysis

The crystal phases of the prepared MNPs, MNP-APTES and MNP-FA were investigated by XRD（Fig. 3B）. The spectrum of MNPs showed the presence of diffraction peaks at 2θ＝30.42°, 35.59°, 43.42°, 53.63°, 57.35°, and

Fig. 2　Schematic illustration of MSPE process.

Fig. 3　（A）FTIR spectra of MNPs, MNP-APTES, and MNP-FA; （B）XRD patterns of MNPs, MNP-APTES, and MNP-FA.


J. Oleo Sci. 66, (7) 771-784 (2017)

776

63.02° and are respectively assigned to the（220）, （311）, （400）, （422）, （511）, and（440）planes of Fe3O4（JCPDS 88-0866）. These indicate that Fe3O4 nanoparticles has a cubic spinel structure36）. Similar diffraction peaks were also ob-served in the MNP-APTES and MNP-FA spectra revealing that the cubic spinel structure of Fe3O4 nanoparticles were not altered during the functionalization process. However, the intensity of the signals decreased for MNP-APTES and MNP-FA, suggesting the presence of APTES and palm fatty acid on the MNPs after modification.3.1.3 Elemental analysis

Elemental analysis was employed to confirm the pres-ence of elements of interests in MNPs, MNP-APTES, and MNP-FA. It was found that the elements present in MNPs are 75.5％ Fe and 24.5％ O（Fig. 4A）. The result indicates that the magnetite（Fe3O4）nanoparticles were successfully synthesized. In addition, APTES is confirmed to have coated the MNPs surface due to the presence of 5.0％ C, 1.3％ Si and 0.9％ N in MNP-APTES（Fig. 4B）. The high percentage of C（9.7％）and O（37.6％）in MNP-FA（Fig. 4C）, proved that palm fatty acid has been successfully functionalized with MNP-APTES. 3.1.4 Morphological analysis

Particle size and morphology of the prepared materials were studied using transmission electron microscopy（TEM）. Figures 5A-C show the TEM images of all synthe-sized nanoparticles. It is clearly observed that all the parti-cles are nano-sized, spherical in shape, and have uniform

distribution of particle size. From the diameter distribution shown in Figs. 5A’-C’, it is observed that the average diam-eters of MNPs, MNP-APTES and MNP-FA are 4.90±2.34 nm, 6.90±2.51 nm, and 6.99±2.81 nm, respectively. The increase of particle size after the functionalization process suggested that APTES and palm fatty acid were success-fully introduced onto the surface of the MNPs.3.1.5 Contact angle analysis

Water contact angle（WCA）analysis was used to charac-terize the wettability of MNPs and MNP-FA. From Fig. 6A, it can be observed that a water droplet on MNPs was dis-persed on the MNPs substrate, suggesting that the MNPs were highly hydrophilic. In contrast, MNP-FA exhibited highly hydrophobic behaviour as the water droplet depos-ited on MNP-FA surface was nearly spherical. The contact angle（CA）measured was 123.6°（Fig. 6B）. This confirms that the hydrophobizing agent, palm fatty acid was coated onto the surface of MNPs.

The relationship between pH and WCA on the hydropho-bic surface of MNP-FA is shown in Fig. 6C. It can be clearly observed that the CA values always remain larger than 110° even when the pH of water droplet was varied from 2.0 to 14.0. This suggests that the pH of the aqueous solution has little effect on the wettability of the MNP-FA surface.

3.2 Comparison of extraction efficiency of MNPs, MNP-APTES and MNP-FA

Figure 7 shows the extraction efficiencies of bare MNPs,

Fig. 4　EDX spectra of（A）MNPs（B）MNP-APTES and（C）MNP-FA.


J. Oleo Sci. 66, (7) 771-784 (2017)

777

MNP-APTES, and MNP-FA. It was found that MNP-FA was the best adsorbent for the extraction of PAHs as it had the highest extraction efficiency for all targeted PAHs. This result can be explained by considering that the long alkyl chains of the fatty acid form a hydrophobic framework which facilitates the adsorption of PAHs through hydro-phobic interaction.

3.3 Optimization of the MSPE conditionsSeveral parameters such as dosage of adsorbent, type of

desorption solvents, volumes of the desorption solvent, ex-traction time, desorption time, pH, and sample volume of

the solution were optimized. Each experiment run was performed in triplicates. The optimization experiments were conducted using spiked standard aqueous solutions containing 100 ng mL－1 PAHs each. Chromatography was used to evaluate the influence of these factors on the PAHs extraction efficiency.3.3.1 Effect of the amounts of adsorbent

Various amounts of MNP-FA ranging from 3 – 25 mg sorbent were tested. As shown in Fig. 8A, the recoveries of PAHs increased when the adsorbent amount was increased from 3 mg to 15 mg. PAHs recovery plateaus after 15 mg due to the active sites on the PAHs being saturated after

Fig. 5　 TEM images of（A）MNPs（B）MNP-APTES and（C）MNP-FA; Diameter distributions of（A’）MNPs（B’）MNP-APTES and（C’）MNP-FA.


J. Oleo Sci. 66, (7) 771-784 (2017)

778

the 15 mg point. Hence, 15 mg of MNP-FA appears to be the optimal amount of adsorbent for MSPE of PAHs and was set as the amount to use in further experiments.3.3.2 Effect of desorption solvent and volume

To recover the sorbent after extraction, the PAHs must be desorbed from the sorbents. Four different common organic solvents（acetonitrile, toluene, hexane and ethyl acetate）were investigated as eluents. The desorption capa-bilities of these eluents are compared in Fig. 8B. As shown in the figure, hexane had a higher desorption capacity compared to other eluents. This fact can be attributed to the high solubility of the target analytes in this solvent. Thus, hexane was selected as the desorption solvent. Addi-tionally, the effect of the volume of desorption solvent on the desorption efficiency was studied from 1 to 3 mL. It

was found that the analytes could be completely desorbed from the sorbent by rinsing the sorbent with 2 mL of hexane.3.3.3 Effect of the extraction and desorption time

Sufficient contact time is needed to attain maximum PAHs adsorption. The extraction time profiles were studied by varying the extraction time between 5 and 25 min. As shown in Fig. 8C, the extraction recoveries of all PAHs in-creased with extraction time up to 15 min, then plateaus after. It can be concluded that the extraction equilibrium between the aqueous phase and the sorbents was reached after 15 min. Similarly, the desorption time profiles were studied by varying the desorption time from 1 to 20 min. As shown in Fig. 8D, a desorption time of 10 min was suffi-cient to completely desorb PAHs from the sorbent. Hence, 15 min and 10 min were respectively selected as the best extraction and desorption times.3.3.4 Effect of pH

In this study, the effect of sample solution pH was studied in the range of 2.0 to 10.0. The sample solution pH was adjusted using volumes of 0.1 M HCl or NaOH. In Fig. 8E, it was observed that high recoveries of all selected PAHs were obtained at pH 6.5. In contrast, low recoveries were observed when the pH was higher or lower. This phe-nomenon can be explained by considering the charged species and charge density on the surface of the sorbent（MNP-FA）. In acidic conditions, high amounts of protons are available, increasing the protonation of the hydroxyl groups on the MNPs surface. The sorbent sites saturates and the sorbent becomes more cationic. In basic condi-tions, the hydroxyl groups from MNPs deprotonates, causing the surface of the adsorbent to be more anionic.

Fig. 6　 The water contact angle of（A）MNPs; （B）MNP-FA and（C）Relationship between pH of water droplet on water CA on the MNP-FA surface.

Fig. 7　 Comparison of the extraction efficiencies of PAHs between MNPs, MNP-APTES and MNP-FA.


J. Oleo Sci. 66, (7) 771-784 (2017)

779

This reduces the hydrophobicity of MNP-FA affecting in-teraction with PAHs. Thus, pH 6.5 was selected as the best pH to use.3.3.5 Effect of sample volume

The effect of the sample volume was examined by varying the sample solution volume between 15 mL to 100 mL. As shown in Fig. 8F, the extraction efficiency in-

creased when the sample volume increases up to 30 mL and then plateaus above 30 mL. Hence, 30 mL of sample volume was selected as the best volume to use.3.3.6 Reusability studies

In order to investigate the recyclability of the adsorbent, the spent adsorbent was washed twice with 5 mL of ethyl acetate and then dried before being used in the next MSPE

Fig. 8　 The effect of（A）amount of sorbent; （B）desorption of solvent; （C）extraction time; （D）desoption time（E）pH, （F）sample volume of the solution on the extraction efficiency of PAHs.


J. Oleo Sci. 66, (7) 771-784 (2017)

780

cycle. The recoveries of PAHs are shown in Fig. 9. It was found that the sorbent can be reused five times without significant loss in the recoveries of all analytes.

3.4 Analytical performanceVarious analytical parameters such as linearity, limit of

detection（LOD）, limit of quantification（LOQ）, and preci-sion were tested to evaluate the MSPE method perfor-mance. The results are listed in Table 1. The calibration curves are linear over a wide range with a correlation of 0.9998. Based on the results obtained, the LOD and LOQ values of the targeted PAHs ranged from 0.01 to 0.05 ng mL－1 and 0.03 to 0.16 ng mL－1, respectively. Intra- and in-ter-day relative standard deviations（RSDs）were assessed to evaluate the precision of the developed method. Satis-factory results were achieved with the intra- day RSD％ being between 3.9％ and 5.8％ and inter-day RSD％ being in the range of 1.1 to 3.1％. This demonstrates the good re-producibility of the current method.

3.5 Application to real samplesUnder optimized conditions, the proposed method was

successfully applied to the analysis of PAHs in real samples represented by leachate and sludge collected from Jeram Landfill, Kuala Selangor. To assess the accuracy of the method, the recoveries of the PAHs from leachate and

sludge at spiking levels of 100, 10, and 5 ng mL－1 were measured. The results obtained are shown in Table 2. The PAHs recoveries from spiked leachate samples ranged from 98.5％ to 113.8％ with the RSDs（n＝5）ranging from 3.5％ to 12.2％, while PAHs recoveries from spiked sludge samples ranged from 81.1％ to 119.3％ with the RSDs（n＝5）ranging from 3.1％ to 13.6％. The results demonstrate the potential of MNP-FA in the application of environmen-tal sample analysis. Figure 10 shows a typical HPLC-DAD chromatograms of the PAHs samples extracted from leach-ate samples using the developed method before and after spiking with 100 ng mL－1 of each PAHs.

3.6 Comparison with other reported MSPE adsorbentsPerformance of the proposed method（MNP-FA-MSPE）

was evaluated by comparing the obtained results with results from similar works reported in literature. The per-formance comparison is shown in Table 3. The perfor-mances were evaluated in terms of amount of sorbent used, extraction time,％ recovery, and LOD. The proposed method（MNP-FA-MSPE）requires a lower amount of ad-sorbent compared to other MSPE adsorbents except g-C3N4/Fe3O4 and Carbon-ferromagnetic nanocomposites. The LOD of our method is low, marking it as sensitive and comparable with others. Good％ recoveries comparable to other works were also achieved.

4 ConclusionIn this study, palm fatty acid functionalized Fe3O4

nanoparticles（MNP-FA）was successfully synthesized, characterized and applied as a MSPE adsorbent coupled with HPLC- DAD for the enrichment of targeted PAHs in leachate and sludge samples. The LOD and LOQ of all se-lected PAHs using the proposed method were in the range of 0.01-0.05 ng mL－1 and 0.03- 0.16 ng mL－1, respectively, with inter- and intra-day precisions being less than 6％. The recoveries for spiked leachate and sludge samples ranged from 98.5％ to 113.8％ and 81.1％ to 119.3％, re-spectively. Owing to its hydrophobic framework, MNP-FA shows a great potential as a MSPE adsorbent for the en-richment of trace PAHs in environmental samples. The ex-

Fig. 9　Reusability cycles.

Table 1　Analytical performance for HPLC-DAD determination of PAHs using MNP-FA.

AnalyteLinearity

R2 LOD (ng mL–1)

LOQ(ng mL–1)

PrecisionLDR

(ng mL–1)Intra-day

(RSD％ n＝7)Inter-day

(RSD％ n＝3)FLT 0.1-100 0.9998 0.05 0.16 5.8 2.3Pyr 0.1-100 0.9998 0.03 0.08 3.8 3.1Cry 0.1-100 0.9998 0.02 0.07 4.2 1.6BaP 0.1-100 0.9998 0.01 0.03 3.9 1.1


J. Oleo Sci. 66, (7) 771-784 (2017)

781

traction was rapid as the MNP-FA could be easily separated from the sample solution using an external magnet. It can be concluded that the proposed method is simple and effi-cient for the pre-concentration of trace PAHs pollutants from environmental samples.

AcknowledgementThe authors would like to take this opportunity to

express their gratitude to the University of Malaya for the research grants（RP020A-16SUS and RP011B-14SUS）, and IPPP grant（PG042-2015A）. The authors also acknowledge the School of Bioprocess Engineering, University of Malay-sia Perlis for providing fellowship to one of the author, Siti Khalijah Binti Mahmad Rozi.

Table 2　 The recoveries and standard deviations of PAHs in real environmental samples with a spiked concentration of 5 ng mL–1, 10 ng mL–1, and 100 ng mL–1 for each analyte.

Analyte Spiked (ng mL–1)

Leachate (n＝5) Sludge (n＝5)Recovery (％) RSD (％) Recovery (％) RSD (％)

FLT 5 103.5 9.7 103.0 8.4 10 109.1 9.6 89.2 3.1100 98.5 5.8 99.4 13.6

Pyr 5 105.2 7.7 107.0 6.0 10 109.1 11.9 81.1 8.7100 100.3 3.5 109.1 8.7

Cry 5 98.9 8.6 84.6 9.5 10 108.9 12.2 108.1 10.1100 113.8 9.4 119.3 3.5

BaP 5 113.6 8.8 92.6 6.5 10 107.5 8.6 103.5 11.1100 110.6 5.2 107.7 8.2

Fig. 10　 HPLC-DAD chromatograms of the PAHs after extraction using proposed MSPE: Non-spiked（A）; and 100 ng mL–1 of each PAHs spiked leachate sample（B）（1）FLT, （2）Pyr, （3）Cry, and（4）BaP.


J. Oleo Sci. 66, (7) 771-784 (2017)

782

Sopporting InformationThis material is available free of charge via the Internet

at http://dx.doi.org/jos.66.10.5650/jos.ess.17016

References1） Zhang, Y.; Tao, S. Global atmospheric emission inven-

tory of polycyclic aromatic hydrocarbons（PAHs）for 2004. Atmos. Environ. 43, 812-819（2009）.

2） Ravindra, K.; Sokhi R.; Grieken, R.V. Atmospheric polycyclic aromatic hydrocarbons: Source attribution, emission factors and regulation. Atmos. Environ. 42, 2895-2921（2008）.

3） Sun, C.; Zhang, J.; Ma, Q.; Chen,Y.; Ju, H. Polycyclic aromatic hydrocarbons（PAHs）in water and sediment from a river basin: sediment-water partitioning, source identification and environmental health risk assess-ment. Environ. Geochem. Health. 39, 63-74（2017）.

4） Xu, S-N.; Zhao, Q.; He, H-B.; Yuan, B-F.; Feng, Y-Q.; Yu, Q-W. Rapid determination of polycyclic aromatic hy-drocarbons in environmental water based on magne-tite nanoparticles/polypyrrole magnetic solid-phase extraction. Anal. Methods 6, 7046-7053（2014）.

5） Liu, L.; Liu, A.; Li, Y.; Zhang. L.; Zhang, G.; Guan. Y. Polycyclic aromatic hydrocarbons associated with road deposited solid and their ecological risk: Implica-tions for road stormwater reuse. Sci. Total Environ. 563-564, 190-198（2016）.

6） Fai, C.; Wong, J.W.C.; Huie, C.W.; Choi, M.M.F. On-line flow injection-cloud point preconcentration of polycy-clic aromatic hydrocarbons coupled with high-perfor-mance liquid chromatography. J. Chromatogr. A 1214, 11-16（2008）.

7） Gholivand, M.B.; Abolghasemi M.M.; Fattahpour, P. Polypyrrole / hexagonally ordered silica nanocompos-ite as a novel fiber coating for solid-phase microex-traction. Anal. Chim. Acta 704, 174-179（2011）.

8） Luo, Y-B.; Cheng, J-S.; Ma, Qiao.; Feng, Y-Q.; Li, J-H. Graphene-polymer composite: extraction of polycyclic aromatic hydrocarbons from water samples by stir rod

sorptive extraction. Anal. Methods 3, 92-98（2011）.9） Huang, Y.; Zhou. Q.; Xie, G. Development of micro-sol-

id phase extraction with titanate nanotube array modi-fied by cetyltrimethylammonium bromide for sensitive determination of polycyclic aromatic hydrocarbons from environmental water samples. J. Hazard. Mater. 193, 82-89（2011）.

10） Shi, Z.; Lee, H.K. Dispersive Liquid - Liquid Microex-traction Coupled with Dispersive μ-Solid-Phase Ex-traction for the Fast Determination of Polycyclic Aro-matic Hydrocarbons in Environmental Water Samples. Anal. Chem. 82, 1540-1545（2010）.

11） Liu, Y.; Li, H.F.; Zhang. J.H.;Maeda, T.; Lin, J.M. Triac-ontyl modified silica gel as a sorbent for the precon-centration of polycyclic aromatic hydrocarbons in aqueous samples prior to gas chromatographic-mass spectrometry determination. Chin. Chem. Lett. 21, 730-733（2010）.

12） Hu, H.; Liu, S.; Chen, C.; Wang, J.; Zou, Y.; Lin, L.; Yao, S. Two novel zeolitic imidazolate frameworks（ZIFs）as sorbents for solid-phase extraction（SPE）of polycyclic aromatic hydrocarbons（PAHs）in environmental water samples. Analyst 139, 5818-5826（2014）.

13） Zhang, S.; Niu, H.; Zhang, Y.; Liu, J.; Shi, Y. Biocompat-ible phosphatidylcholine bilayer coated on magnetic nanoparticles and their application in the extraction of several polycyclic aromatic hydrocarbons from envi-ronmental water and milk samples. J. Chromatogr. A 1238, 38-45（2012）.

14） Wang, W.; Ma, R.; Wu, Q.; Wang, C.; Wang, Z. Magnetic microsphere-confined graphene for the extraction of polycyclic aromatic hydrocarbons from environmental water samples coupled with high performance liquid chromatography – fluorescence analysis. J. Chro-matogr. A 1293, 20-27（2013）.

15） Liu, Q.; Shi, J.; Wang, T.; Guo, F.; Liu, L.; Jiang, G. Hemimicelles / admicelles supported on magnetic gra-phene sheets for enhanced magnetic solid-phase ex-traction. J. Chromatogr. A 1257, 1-8（2012）.

16） Liu, Q.; Shi, J.; Cheng, M.; Li. G.; Cao, D.; Jiang, G. Preparation of graphene-encapsulated magnetic mi-

Table 3　Comparison of MNP-FA with other reported MSPE for extraction of PAHs.

Material Amount of sorbent (mg)

Extraction time (min.) ％ Recovery LODs (ng mL–1) Ref.

MNP-FA 15 15 81.1–119.3 0.01–0.05 This studyFe3O4@Ag@b-TMP-DTPA NPs 50 20 82.4–109.0 0.02–0.1 33)Fe3O4/Graphene oxide 40 10 76.8–103.2 0.09–0.19 37)Ionic Liquid / Fe3O4 30 7 75.0–102.0 0.04–1.11 38)g-C3N4/Fe3O4 10 10 80.0– 99.8 0.05–0.1 18)G/ Fe3O4@PT 20 4 83.0–107.0 0.03–80.0 39)Carbon-ferromagnetic nanocomposites 10 30 － 0.015–0.065 40)


J. Oleo Sci. 66, (7) 771-784 (2017)

783

crospheres for protein/peptide enrichment and MAL-DI-TOF MS analysis. Chem. Commun. 48, 1874-1876（2012）.

17） Wan Ibrahim, W.A.; Nodeh, H.R.; Aboul-Enein, H.Y.; Sanagi, M.M. Magnetic solid-phase extraction based on modified ferum oxides for enrichment, preconcentra-tion, and isolation of pesticides and selected pollut-ants. Crit. Rev. Anal. Chem. 45, 270-287（2015）.

18） Wang, M.; Cui, S.; Yang, X.; Bi, W. Synthesis of g-C3N4/Fe3O4 nanocomposites and application as a new sor-bent for solid phase extraction of polycyclic aromatic hydrocarbons in water samples. Talanta 132, 922-928（2015）.

19） Takahashi, A.; Tanaka, H.; Minami, N.; Kurihara, M.; Kawamoto, T. Simultaneous enhancement of Cs-ad-sorption and magnetic propertiEs of Prussian blue by thermal partial oxidation. Bull. Chem. Soc. Jpn. 88, 69-73（2015）.

20） Petcharoen, K.; Sirivat, A. Synthesis and characteriza-tion of magnetite nanoparticles via the chemical co-precipitation method. Mater. Sci. Eng., B 177, 421-427（2012）.

21） Simeonidis, K.; Mourdikoudis, S.; Kaprara, E.; Mi-trakas, M.; Polavarapu, L. Inorganic engineered nanoparticles in drinking water treatment: a critical review. Environ. Sci.: Water Res. Technol. 2, 43-70（2016）.

22） Abe, H.; Liu, J.; Ariga, K. Catalytic nanoarchitectonics for environmentally compatible energy generation. Mater. Today 19, 12-18（2016）.

23） Ding, J.; Gao, Q.; Luo, D.; Shi, Z.; Feng, Y. n-Octadecy-lphosphonic acid grafted mesoporous magnetic nanoparticle: Preparation, characterization, and appli-cation in magnetic solid-phase extraction. J. Chro-matogr. A 1217, 7351-7358（2010）.

24） Bunkoed, O.; Kanatharana, P.; Extraction of polycyclic aromatic hydrocarbons with a magnetic sorbent com-posed of alginate, magnetite nanoparticles and multi-walled carbon nanotubes. Microchim. Acta 182, 1519-1526（2015）.

25） Liu, Y.; Li, H.; Lin, J. 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 spectrome-try. Talanta 77, 1037-1042（2009）.

26） Long, Y.; Chen, Y.; Yang, F.; Chen, C.; Pan, D.; Cai, Q.; Yao, S. Triphenylamine-functionalized magnetic mic-roparticles as a new adsorbent coupled with high per-formance liquid chromatography for the analysis of trace polycyclic aromatic hydrocarbons in aqueous samples. Analyst 137, 2716-2722（2012）.

27） Amiri, A.; Baghayeri, M.; Kashmari, M. Magnetic nanoparticles modified with polyfuran for the extrac-

tion of polycyclic aromatic hydrocarbons prior to their determination by gas chromatography. Microchim. Acta 183, 1-8（2015）.

28） Wang, H.; Zhao, X.; Meng, W.; Wang, P.; Wu, F.; Tang Z.; Han, X.; Giesy, J.P. Cetyltrimethylammonium bromide-coated Fe3O4 magnetic nanoparticles for rapid analysis of 15 trace polycyclic aromatic hydrocarbons in aquat-ic environments by UPLC-FLD. Anal. Chem. 87, 7667-7675（2015）.

29） Christie, W.W. Gas chromatography and lipids. Oily Press（foremaly of Ayr）, 39（1989）.

30） Salimon, J.; Abdullah, B.M.; Salih, N. D-optimal design optimization of Jatropha curcas L. Seed oil hydrolysis via alkali-catalyzed reactions. Sains Malaysiana 41, 731-738（2012）.

31） Can, K.; Ozmen, M.; Ersoz, M. Immobilization of albu-min on aminosilane modified superparamagnetic mag-netite nanoparticles and its characterization. Colloids Surf., B 71, 154-159（2009）.

32） Feng, B.; Hong, R.Y.; Wang, L.S.; Guo, L.; Li, H.Z.; Ding J, Zheng, Y.; Wei, D.G. Physicochemical and engineer-ing aspects synthesis of Fe3O4 / APTES / PEG diacid functionalized magnetic nanoparticles for MR imaging. Colloids Surf., A 328, 52-59（2008）.

33） Tahmasebi, E.; Yamini, Y. Facile synthesis of new nano sorbent for magnetic solid-phase extraction by self as-sembling of bis-（2,4,4-trimethyl pentyl）-dithiophos-phinic acid on Fe3O4@Ag core@shell nanoparticles: Characterization and application. Anal. Chim. Acta 756, 13-22（2012）.

34） Zhang, S.; Niu, H.; Hu, Z.; Cai, Y.; Shi. Y. Preparation of carbon coated Fe3O4 nanoparticles and their applica-tion for solid-phase extraction of polycyclic aromatic hydrocarbons from environmental water samples. J. Chromatogr. A 1217, 4757- 4764（2010）.

35） Mahmoud, M.E.; Ahmed, S.B.; Osman, M.M.; Abdel-fattah, T.M. A novel composite of nanomagnetite-im-mobilized-baker’s yeast on the surface of activated carbon for magnetic solid phase extraction of Hg（II）. Fuel 139, 614-621（2015）.

36） Marquez, F.; Morant, C.; Sanz, J.M.; Elizalde, E. At-tachment of magnetite nanoparticles on carbon nano-tubes bundles and their response to magnetic fields. J. Nanosci. Nanotechnol. 9, 3810-3814（2009）.

37） Han, Q.; Wang, Z.; Xia, J.; Chen, S.; Zhang, X.; Ding, M. Facile and tunable fabrication of Fe3O4 / graphene ox-ide nanocomposites and their application in the mag-netic solid-phase extraction of polycyclic aromatic hy-drocarbons from environmental water samples. Talanta 101, 388-395（2012）.

38） Galan-Cano, F.; Del Carmen Alcudia-Leon, M.; Lucena, R.; Cardenas, S.; Valcarcel, M. Ionic liquid coated mag-netic nanoparticles for the gas chromatography/mass spectrometric determination of polycyclic aromatic


J. Oleo Sci. 66, (7) 771-784 (2017)

784

hydrocarbons in waters. J. Chromatogr. A 1300, 134-140（2013）.

39） Mehdinia, A.; Khodaee, N.; Jabbari, A. Fabrication of graphene/Fe3O4@polythiophene nanocomposite and its application in the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from environmen-

tal water samples. Anal. Chim. Acta 868, 1-9（2015）.40） Bai, L.; Mei, B.; Guo, Q.; Shi, Z.; Feng, Y. Magnetic sol-

id-phase extraction of hydrophobic analytes in envi-ronmental samples by a surface hydrophilic carbon-ferromagnetic nanocomposite. J. Chromatogr. A 1217, 7331-7336（2010）.

novel palm fatty acid functionalized magnetite

Documents