The Synthesis Of ?-hole Bond Functionalized Solid Phase Extraction Sorbent And Its Application In The Determination Of Polycyclic Aromatic Hydrocarbons In Water

Objective:The new interaction ?-hole bond was introduced in solid phase extraction(SPE)to improve the selectivity and sensitivity in the determination of polycyclic aromatic hydrocarbons(PAHs).Methods:Taking benzo(a)pyrene(BaP)as the model molecule,the interaction between BaP and perfluorobenzene which is typical ?-hole bond donor was studied by theoretical computation and 1H nuclear magnetic resonance spectroscopy(1H NMR)analysis.Then perfluorobenzene bonded silica(PFB)sorbent was synthesized and characterized by infrared spectrometry and elemental analysis.By optimizing the conditions of SPE and high performance liquid chromatography(HPLC),a new analytical method was established and applied to the detection of PAHs in environmental water samples.The retention of 16 priority PAH pollutants which designated by the United States Environmental Protection Agency(EPA)was investigated on the PFB and C18 columns,respectively.Results:The bonding energy of ?-hole bond which BaP and PFB was calculated about-17.28 kJ/mol.The binding constant was 0.36 L/mol by 1H NMR.Compared with the raw materials,the synthetic sorbent was yellow.The PFB sorbent had not N-H stretching vibrations by infrared spectrometry.And the new bands such as C=O stretching vibration,skeleton vibration of benzene ring and C-F stretching vibration were appeared in PFB sorbent spectrum,which proved that pentafluorobenzoyl chloride has been bonded on the silica gel.The bonding amount calculated by elemental analysis was 7.98 mmol/g.Then SPE cartridges were prepared by packing 200 mg of adsorbent in each 3 mL empty SPE cartridge with upper and lower frits to avoid adsorbent loss.All of the steps were driven by gravity.The cartridges were washed with 20 mL dichloromethane and preconditioned with 20 mL methanol and 5 mL distilled water,and then were loaded with the sample solutions.The cartridge was dried by negative pressure for 10 min.Subsequently,the analytes were eluted from the cartridges using 2 mL dichloromethane.The elute was collected,evaporated to near dryness by a rotary vacuum evaporator at room temperature and the residue was redissolved in 1 mL of acetonitrile.The elution was filtered and analysed by HPLC.Compared with traditional C18 sorbent,PFB sorbent showed higher adsorptivities for most PAHs,especially for the PAHs with 4-6 benzene rings,of which the recoveries increased about 20%.Under the optimized conditions,the proposed method was successfully applied to the analysis of 16 PAHs in environmental water samples.The linear range was 0.004?4.000 ?g/L and correlation coefficients(R2)were 0.9992?0.9999.The average recoveries of PAHs at 0.200 ?g/L spike level were in the range of 67.54?95.33%with relative standard deviations(RSDs)less than 10.56%(n=3).The limits of detection(LOD)were in the range of 0.002?0.080 ?g/L,and the limits of quantitative(LOQ)were in the range of 0.004?0.200 ?g/L.Conclusion:BaP can form ?-hole bond with perfluorobenzene.Then PFB sorbent was synthesized.Compared with the conventional C18 sorbent,the newly synthesized ?-hole bound functionalized sorbent can improve the SPE efficiency for PAHs.This result proves that applying the special interaction of ?-hole bond in SPE can improve the selectivity and enrichment efficiency.This work offer a new way of thinking for the design of selective sorbent.