Application Of Molecularly Imprinted Functional Materials In Environmental Detection Of Carbonyl Pollutants

Carbonyl compounds?CBs?mainly consist of aldehydes and ketones,which are carcinogenic and mutagenic and do harm to human health.Therefore,the development of more sensitive and fast determination methods is mandatory to identify the trace carbonyl compounds in the environment.In the traditional method,2,4-dinitrophenylhydrazine?2,4-DNPH?is used to convert carbonyls compounds into carbonyl-DNPH derivatives?which are actually hydrazones?prior to their determination by HPLC.To make sure the derivative reaction can conduct completely,a large amount of 2,4-DNPH has been applied.However,the unreacted 2,4-DNPH residual can affect the quantitative analysis of carbonyls by co-eluting with carbonyl-DNPH derivatives during chromatography separation.In addition,the existence of a large number of 2,4-DNPH has been found to limit the degree of pre-concentration of the target sample by precipation.Magnetic molecularly imprinted polymer microspheres?MMIPs?,which have the specific recognition properties to DNPH,have been prepared by using DNAN as the dummy template,methacrylic acid as the functional monomer,ethylene glycol dimethyl acrylate?EDMA?or divinylbenzene?DVB?as the cross-linker and magnetic Fe₃O₄ as the carrier.In this study,MMIPs was characterized by scanning electron microscope and laser particle size analyzer;The recognition effect of two kinds of MMIPs?MMIP-EDMA and MMIP-DVB?were discussed;the influences of factors,such as pH and adsorption time,on the adsorption properties of MMIPs were considered;and the recognition ability of the MMIPs was analyzed by selective adsorption experiments.MMIP-EDMA has shown selective binding to 2,4-DNPH from complex sample matrix and was found to be separated easily from a matrix under an external magnetic field.Therefore,MMIP-EDMA has been applied for the determination of carbonyl compounds in air sample and aqueous sample.On one side,MMIP-EDMA has been applied to the monitoring of carbonyl compounds in the air.The concentrations of carbonyl compounds in the atmosphere are typically of trace level,thus a long sampling schedule has usually been adopted.To ensure a high collection efficiency,a large amount of 2,4-DNPH has been applied during the sampling process.The unreacted 2,4-DNPH residual can affect the quantitative analysis of carbonyls by co-eluting with carbonyl-DNPH derivatives during chromatography separation.In this study,MMIP-EDMA selective for 2,4-DNPH was used to remove the excess of the derivatization reagent 2,4-DNPH.Owing to the clearance of the unreacted 2,4-DNPH from air sample solution,lower detection limit,higher collection efficiency and less sampling time have been realized.The capillary electrophoresis?CE?methodology has been proved to be superior than HPLC about small sample size.In the present work,different carbonyls have been detected with a 15-min sampling schedule.The coupling of MMIPs with CE method was applied for fast monitoring of carbonyl pollutants in ambient PM2.5 in Guangzhou winter.All of the 15targeted carbonyl compounds have been found in atmospheric PM2.5 samples.The concentrations of multi-carbon carbonyl compounds,especially isovaleraldehyde,were found increase sharply in PM2.5 in the haze weather.A statistical method was used to evaluate the correlationamongdifferentcarbonyls,andtheconcentrationratioof formaldehyde/acetaldehyde?C1/C2?and acetaldehyde/propionaldehyde?C2/C3?was used to estimate the pollutant sources.Results imply that the human activities have seriously affected the air quality and caused the happen of haze weather,which should arouse much attention.On the other side,MMIP-EDMA has been used as selective sorbents to extract target carbonyl compounds from aqueous sample.In the present research,a method?MMIP-CE?coupling the magnetic molecularly imprinted solid phase extraction?MMISPE?with capillary electrophoresis?CE?was developed.The influence of extraction time and the amount of MMIPs on the extraction properties of MMIPs were investigated.The result reveals that MMIPs show rapid equilibrium,high adsorption capacity and specific selectivity.By dispersing 200 mg·L^-1 MMIP-EDMA in the aqueous sample,the best extraction effect of carbonyl compounds can be achieved under optimal conditions.The results show that the linear correlation coefficients of 8 carbonyl derivatives are more than 0.999,the recovery rates are between 78.9-119.6%,the relative standard deviations are less than 5%and the detection limits are 0.0061-0.0439 mg/L.The MMIP-CE method shows advantages in extraction,enrichment and sample clean-up over the traditional liquid-liquid extraction.It is an ideal method for the detection of trace carbonyl compounds in aqueous sample.The established method has been applied to the detection of aldehydes and ketones in drinking water.The results show that the content of natural water will be affected by the surrounding humus,so water safety should be paid attention to the drinking of natural water.