Solid-phase Microextraction Fibers Based Metal-Organic Nanomaterials For Detection Of Trace Persistent Organic Pollutants In Water Samples

Persistent organic pollutants(POPs),a class of organic compounds what can be existed in the environment for a long time.It can be accumulated though the food chains(webs),and harm to the health of humans and animals.POPs are persistence,accumulating,highly toxic,and can be migrated a long-distance through variety media.It is necessary to research and solve the pollution of POPs.Therefore,it is important to develop a rapid,accurate,inexpensive and sensitive method for protecting environmental monitoring and human health.In this work,two kinds of novel materials were synthesized independently: Cd-MONTs and Zn-MONTs.They are used as the solid phase microextraction coating and develop a new method to detect the PCBs and NPAHs in water,respectively.And the developed methods are validated against several real water samples in different locations.At the same time,the adsorption mechanisms of them are discussed in the paper.The main research results are as follows:1.Cd-MONTs were synthesized and applied to the determination of PCBs in water.The hydrothermal reaction mixture of CdCl2·2.5H2 O,oxalic acid,1,3,5-benzenetricarboxylic acid,o-phenylenediamine,NaOH,and water was stirred for approximately 30 min at room temperature.The reaction was generated under high temperature and high pressure to obtain block crystals.Cd-MONTs has been developed to use solid-phase microextraction(SPME)coupled with gas chromatography–mass spectrometry to analyze the trace of seven PCBs(PCB-28,52,101,118,138,153,180)in real seawater samples.Cd-MONTs were grounded into power and used as a novel SPME coating via physical adhesion.The coated fibers of Cd-MONTs exhibited good thermal stability about 385?.The Cd-MONTs-coated fiber possessed higher adsorption efficiency than Cu-MONTs-coated fiber,30?m polydimethysiloxane(PDMS)fiber and 65?m PDMS / Divinylbenzene(PDMS/DVB)fiber for 7PCBs in water sample.Plackett-Burman design was employed to optimize the direct immersion extraction factors affecting the extraction efficiency through a response surface methodology.Important parameters,such as extraction time,ionic strength,pH,agitation speed,and desorption temperature and time,were optimized in orthogonal experiment.Under the optimal condition,the novel method achieved low limits of detection of 1.80–8.73 pg L-1and a wide linear range of 10–5000 pg L-1 for 7 PCBs.The developed method was validated with three seawater samples and the recoveries of the three spiked water samples ranged from78.3 to 110.0 %,which met the demand of trace analysis for PCBs.2.Zn-MONTs were synthesized and applied to the determination of NPAHs in water and soil.Zn(NO3)·6H2O(10 mg,0.03 mmol),H2ATIBDC(10 mg,0.02 mmol)and 4,4`-bipy(10mg,0.052 mmol)were mixed in 8 mL of a mixed solvent of N,N-dimethyl formamide,ethanol and H2O(v/v,5:2:1).The reaction mixture was placed in airtight container,which diffusion of diethyl ether into the resulting clear solution for 10 days yielded a large amount of yellow prismatic crystals.They were isolated by filtration,and washed with water and then drying in the oven about 200°C for 24 h.Zn-MONTs has been developed to use solid-phase microextraction(SPME)coupled with gas chromatography–mass spectrometry to analyze the trace of 6 NPAHs(3-Nitrobiphenyl,9-Nitroanthracene,9-Nitrophenanthrene,3-Nitrofluoranthene,1-nitropyrene,6-Nitrochrysene)in water samples and soil sample.Zn-MONTs were grounded into power and used as a novel SPME coating via physical adhesion.The coated fibers of Zn-MONTs exhibited good thermal stability about 335?.The Zn-MONTs-coated fiber possessed higher adsorption efficiency than 100?m polydimethysiloxane(PDMS)fiber,50/30?m PDMS/ Carboxen/ Divinylbenzene/(DVB/CAR/PDMS)fiber and 65 ?m PDMS/DVB for 6 NPAHs in water sample.Single factor optimization method was used to argue the important influencing factors on direct immersion extraction for NPAHs in water samples.A possible NPAHs extraction mechanism enabled by the Zn-MONTs-coated fiber is proposed.Under the optimal condition,the novel method achieved low limits of detection of 1.36 ~7.31 ng L-1 and a wide linear range of 10 ~ 5000 ng L-1 for 6 NPAHs.For a single Zn-MONT-coated fiber,the relative standard deviations ranged from 1.7 to 10.2% and for three parallel Zn-MONT-coated fibers,the fiber-to-fiber reproducibility ranged from 6.1 to 12.8 %,enrichment factor from 1510 to17684 for the 6 NPAHs in a day.The developed method was validated with water samples and soil sample,and satisfactory results were obtained,which recoveries were71.2 to 114.2%.