Solid-phase Microextraction Of Organic Pollutants In Environmental Water Samples

Solid-phase microextraction(SPME)is a green sample preparation technique in which no solvent or a small amount of solvent is used and sampling,enrichment,purification and concentration are combined together in one step.For the analysis of organic pollutants in environmental waters,polyimide(PI)was adopted as extraction material and several SPME geometries including stir bar sorptive extraction(SBSE),thin film microextraction(TFME),and dispersive solid phase microextraction(d-SPME)were evaluated in this thesis.The chromatographic method was used for the qualitative and quantitative analysis of target analytes.In Chapter two,in order to reduce the adsorption of water on polar extraction phase materials and inhibit the negative effects of water on chromatographic system,ultra-thin polydimethylsiloxane(PDMS)layer was coated on the polar extraction materials.PI and poly(phthalazine ether sulfone ketone)(PPESK)sorptive bars were firstly prepared by immersion precipitation phase inversion method and then ultrathin PDMS was coated on PI and PPESK extraction phase coating.After extraction of analytes by the PI/PDMS and PPESK/PDMS sorptive bars,thermal desorption(TD)was utilized to introduce the extracted analytes into gas chromatography/mass spectrometry(GC/MS)for analysis.The PI/PDMS and PPESK/PDMS sorptive bars could resist high temperature up to 260 °C and reduce the amount of adsorbed water which significantly inhibited the damage of water to the column and detector.With polar phenolic compounds and nitroaromatic compounds as model analytes,it was demonstrated that the ultrathin PDMS layer(less than 1 μm)could reduce the amount of adsorbed water by more than 93% while the extraction recoveries of target analytes were decreased by less than 30%.These results showed that the ultra-thin PDMS layer could effectively inhibit the water adsorption problem of the polar extraction phase without decreasing the extraction efficiency significantly.The strategy of coating ultra-thin PDMS layer on polar extraction phase materials proposed a good application prospect in the field of real water sample analysis.In Chapter three,in order to achieve ultra-fast equilibrium SPME,polyimide/polyvinylpyrrolidone(PI/PVP)nanofiber membranes were electrospun and applied as sorbent for thin film microextraction(TFME)to extract organic pollutants in water.The prepared PI/40% PVP electrospun nanofiber membranes could fully stretch in aqueous solution,showing a well dispersed state just like nano sols,and thus a large specific surface area and a short mass transfer distance were obtained.The extraction performance was evaluated with phthalate plasticizer as model analytes.This method possessed a large linear correlation coefficients(r ≥0.99),a wide linear ranges(0-100 μg/L),good precisions(0.3-14.7%),low detection limits(0.005～-0.040 μg/L),and high relative recoveries(76.1–-121.9%)for real water samples.In Chapter four,PI nanospheres were prepared through phase transformation method by rapidly mixing the dimethylformamide solution of PI and water.The PI nanospheres could be well suspended and dispersed in aqueous solution and the size distribution range was 100-500 nm.The study of dispersed solid phase microextraction(d-SPME)based on the prepared PI nanospheres was carried out and the extraction performance was evaluated using phthalate plasticizer as model analytes.The high linear correlation coefficients(r≥0.993),wide linear ranges(0-100 μg/L),low detection limits(0.002～-0.080 μg/L),and high relative recoveries(62.6-128.3%)were obtained.In this thesis,several SPME techniques were studied for the analysis of organic pollutants in environmental waters and extraction performances including wide linear range,low detection limit and good precision were obtained.The method performances could meet the demands of national standard and practical application.Our studies would furtherly promote the application of SPME method to the analysis of real environmental water samples.