| Objectives Hydroxyl polycyclic aromatic hydrocarbons?OH-PAHs?are commonly used as exposure markers of polycyclic aromatic hydrocarbons?PAHs?.Generally,solid-phase extraction process is required to remove impurities and enrich target substances prior to instrument analysis.However,the traditional solid-phase extraction columns are usually disposable and it suffers the difficulity of limited extraction efficiency.Graphene oxide?GO?as a fascinating two-dimensional carbon material,has been explored as an excellent adsorbent in sample pretreatment.Nevertheless,GO is generally prone to aggregate and the useage of its large surface area is quite limited.Besides,the single-layer thickness results in high pressure of packed cartridge and sorbent escaping.To overcome these unexpected obstacles,the fabrication of GO incorporated monolith was proposed in this study and developed as sorbent for simple and efficient determination of six OH-PAHs?2-hydroxy-naphthalene,2-hydroxy-fluorene,9-hydroxy-fluorene,2-hydroxy-phenanthrene,9-hydroxy-phenanthrene and 1-hydroxy-pyrene?in urine coupled with liquid chromatography-tandem mass spectrometry.Methods 1 The GO incorporated monolith was fabricated using a single crosslinker of ethylene glycoldimethacrylate?EDMA?and introduced to extract OH-PAHs from urine samples.The incorporation of GO into the monolith was characterized by scanning electron microscope,transmission electron microscope,X-ray diffractometer and surface area and pore size distribution analyzer.2 The prepared poly?GO-EDMA?monolith was developed as adsorbent for solid-phase extraction of trace OH-PAHs in urine samples.The effects of GO amount?0,1.2,1.5 and 1.7 mg?,washing solvent?methanol/H2O?2/8,v/v?,25 mmol.L-1 NH4 OAc,and 25 mmol.L-1 Na H2PO4?,eluting solvent?methanol,ethyl acetate and acetone?,and its volume?1,2 and 3 m L?on the extraction performance were investigated.3 In this study,poly?GO-EDMA?monolithic syringe based solid-phase extraction in combination of liquid chromatography-tandem mass spectrometry was applied for the determination of six OH-PAHs in urine samples.Under the optimized conditions,the method was validated with limit of detection,limit of quantification,linear range,accuracy and precision.Enrichment effect,reproducibility and reusability of poly?GO-EDMA?monolith were also evaluated.Results 1 The characterision results of scanning electron microscopy,transmission electron microscopy,X-ray diffraction and automatic specific surface area and porosity analyzer showed that GO and EDMA were successfully copolymerized and the monolithic column had uniform porous structure.Additionally,the specific surface area of poly?GOEDMA?material was found to be 291.6 m2.g-1 and the result facilitated the monolith to offer high extraction efficiency when performed as solid-phase extraction sorbent.2 The fabricated monoliths gave higher adsorption efficiency and capacity than the neat polymer monolith and commercial C18 sorbent.The adsorption capacity of poly?GO-EDMA?monolith was found to be 15.8 mg.g-1 for 2-hydroxy-naphthol,which was 3-fold higher than that of C18 sorbent(5.75 mg.g-1).With the incorporated amount of 1.5 mg,the washing solvent of 4 m L of NH4OAc?25 mmol.L-1?and the eluting solvent of 2 m L of ethyl acetate,the monolith gave the best adsorption efficiency and recovery of OH-PAHs.3 The linear ranges of calibration curve were 0.1-500 ng.m L-1 for 2-hydroxy-naphthol,0.3-1500 ng.m L-1 for 9-hydroxy-fluorene and 2-hdroxy-fluorene,0.2-100 ng.m L-1 for 2-hydroxy-phenanthrene,9-hydroxy-phenanthrene and 1-hydroxy-pyrene.All correlation coefficients?r?were higher than 0.998.The limits of detection were in the range of 0.02-0.1 ng.m L-1 and the limits of quantification were 0.07-0.33 ng.m L-1.The recoveries at three spiked levels ranged from 77.5% to 97.1%.The intra-day?n=3?and inter-day?n=3?precisions ranged from 2.4% to 8.7% and 2.9% to 9.9%,respectively.The intra column-tocolumn relative standard deviations for three columns prepared in one batch were in the range of 3.1%-7.6%.The batch-to-batch relative standard deviations for three parallel poly?GO-EDMA?monolithic syringes varied from 4.8% to 9.8%.The relative standard deviation for six replicate cycles was ? 5.8%.The developed method was successfully applied for the determination of OH-PAHs in human urine.Conclusions A poly?GO-EDMA?monolithic syringe was fabricated as adsorbent and developed for simple and efficient analysis of six OH-PAHs in human urine using liquid chromatography-tandem mass spectrometry.Good recoveries,low limits of detection,superior reproducibility and satisfactory precision were obtained.The incorporation of GO into the polymer monolith significantly improved the extraction performance for the target OH-PAHs in comparison with the neat polymer monolith.The ease of fabrication,stability,and robustness made it as an efficient sorbent for extraction and preconcentration of OHPAHs from urine samples.Figure 20;Table 7;Reference 146... |
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