The Preparation And Application Of Solid-phase Microextraction Coating Based On Layered Double Hydroxides

In this study,magnesium/aluminum layered double hydroxide?Mg/Al-LDH?,hydrogen peroxide?H₂O₂?treated magnesium/aluminum layered double hydroxide?Mg/Al-LDH-H₂O₂?andsodiumdodecylsulfonate?SDS?modified magnesium/aluminum layered double hydroxide?Mg/Al-SDS-LDH?were prepared.Then,the as-prepared materials were coated on stainless steel wire to construct three solid-phase microextraction?SPME?fibers.After that,the SPME fibers were coupled with gas chromatography?GC?to establish the SPME-GC method for the determination of phthalate esters?PAEs?in aqueous and real water samples were detected.The main contents are as follows:?1?Mg/Al-LDH was prepared by urea hydrolysis method,then the Mg/Al-LDH was fixed on stainless steel wire to construct SPME fiber,which was used to extract PAEs from aqueous.The extraction temperature,extraction time and ionic strength affecting the extraction efficiency of SPME fiber were optimized.The selected extraction temperature was 50?,extraction time was 40 min and ionic strength was10%?NaCl,w/v?.Under the optimum extraction conditions,linear ranges of 10⁴00?g L^-11 for benzyl butyl phthalate?BBP?and di?2-ethylhexyl?phthalate?DEHP?,1⁴00?g L^-11 for di-n-butyl phthalate?DBP?and 10⁵00?g L^-11 for di-n-octyl phthalate?DNOP?were observed.The correlation coefficients?R²?ranged from0.9831 to 0.9940.The limits of detection?LODs?and limits of quantification?LOQs?of four analytes ranged from 0.24 to 2.31?g L^-1and 0.81 to 7.69?g L^-1,respectively.The intra-day and inter-day precision of single fiber are less than 15.3%and 8.7%,and the fiber-to-fiber reproducibility ranged from 8.3%to 16.7%.The established SPME-GC method was applied to the determination of target PAEs in real water samples and the recoveries were 79.6%¹10.5%.?2?Mg/Al-LDH was treated with H₂O₂ to obtain Mg/Al-LDH-H₂O₂.Then,the Mg/Al-LDH-H₂O₂ was applied as coating to prepared SPME fiber.The fiber was combined with GC to establish a method for the detection of PAEs in aqueous.The optimum extraction temperature of the fiber was 60?,extraction time was 40 min and ionic strength was 15%?NaCl,w/v?.Under the optimum conditions,the established SPME-GC method has a good linearity in the range of 2⁵00?g L^-1.The LODs and LOQs were 0.42¹.29?g L^-1and 1.40⁴.31?g L^-1,respectively.The repeatability of one fiber was less than 20.0%,and the relative standard deviation?RSD?between three fibers were between 8.5%and 20.4%.The method was applied to the determination of PAEs in real water samples.The recoveries obtained by the spiked experiments were 79.4%¹07.2%.?3?Mg/Al-SDS-LDHwassynthesizedby intercalating SDS between Mg/Al-LDH layers.The synthesized material was employed as a coating for SPME fiber.The surface properties of the fiber was characterized by Fourier transform infrared spectrometer?FTIR?,scanning electron microscope?SEM?and specific surface and pore size analyzers.In order to obtain higher extraction efficiency,the extraction temperature,extraction time and ionic strength of fiber were optimized.The optimized results were extraction temperature 50?,extraction time 40 min and ionic strength 15%?NaCl,w/v?.Under optimal conditions,the linear ranges of DBP,BBP,DEHP and DNOP were 5⁴50?g L^-1,10⁴00?g L^-1,5⁴50?g L^-1and 10⁴00?g L^-11 with R² between 0.9653 and 0.9869.The LODs and LOQs were 0.30².79?g L^-11 and 0.99⁹.61?g L^-1,respectively.The RSD of single fiber was less than 16.8%and RSD of fiber to fiber was 6.1%to 19.9%.In the plastic cup cooling water and throw-away lunchbox cooling water,DEHP was detected with the concentrations at5.84?g L^-1and 6.51?g L^-1,respectively.The recoveries of the spiked experiments ranged from 84.0%to 119.1%.The extraction efficiency of three homemade SPME fibers and commercial polydimethylsiloxane?PDMS?fiber for PAEs were compared.The results showed that the three homemade fibers have better extraction performance than commercial fiber.Among them,Mg/Al-LDH-H₂O₂ fiber has the higher extraction efficiency for most of PAEs selected in this study.