| Sample pretreatment technology plays an important role in analyzing organic pollutants.The accuracy of the results strongly dependent on the sample pretreatment process.In order to overcome the disadvantage of tedious workup,large amounts of toxic organic solvent usage in the classical LLE extraction of environmental organic pollutants,many novel methods have been developed,such as solid phase extraction (SPE),solid phase microextraction(SPME),membrane extraction(ME),microwave assisted extraction(MAE),accelerated solvent extraction(ASE),and liquid phase microextraction(LPME).As these methods use small or no organic solvents,they are regarded as green pretreatment technology.This thesis systematically studied the application of hollow fiber supported liquid membrane liquid phase microextraction (HF-SLM) in environmental analysis.Hollow fiber supported liquid membrane liquid phase microextraction is a novel sample pretreatment technique developed in recent years.With inexpensive apparatus, LPME virtually uses negligible organic solvents,and combines extraction, preconcentration and sample introduction in one step.This technique has been combined with gas chromatography(GC),high performance liquid chromatography (HPLC) and capillary electrophoresis(CE) for the analysis of non-volatile and semivolatile environmental contaminations and drugs of low concentration in various samples.This dissertation focus on developments of new models of HF-LPME for the analysis of environmental pollutants:1.A new a passive sampling device based on hollow fiber membrane-supported polypropylene glycol(PPG) was developed for sampling and determining Geosmin and 2-methylisoborneol in surface water.The material and preparation procedure for preparing the sampling device were optimized,and the effects of sampling time, sample salinity and pH on the sampling efficiency were studied.It was found that PPG 4000 exhibited high extraction selectivity and efficiency for the target Geosmin and 2-methylisoborneol.By coupling this sampling device with headspace solid-phase microextraction-GC/MS,very low detection limit(0.1 ng/L) was obtained for Geosmin and 2-methylisoborneol.This developed sampling device was successfully applied to field sampling of Geosmin and 2-methylisoborneol in Taihu lake,China.2.A simultaneously performed two/three-phase hollow fiber-based liquid-phase microextraction(HF-LPME) method was developed for the determination of aromatic amines with a wide range ofpKa(-4.25-4.6) and log Kow(0.9-2.8) in environmental water samples.The mass transfer of the analytes from the donor phase through the organic membrane phase into acceptor phase was driven by both the counter-coupled transport of hydrogen ions and the pH gradient.Afterwards,the hollow fiber was eluted with 50μL methanol to capture the analytes from both the organic membrane and the acceptor phase.The proposed procedure worked very well for real environmental water samples with microgram per liter level of analytes,and good spike recoveries(80-103%) were obtained.3.By using ionic liquid as the membrane liquid and tri-n-octylphosphine oxide (TOPO) as an additive,hollow fiber supported liquid phase microextraction (HF-LPME) was developed for the determination of five sulfonamides in environmental water samples by high performance liquid chromatography with ultraviolet detection.The extraction solvent and the parameters affecting the extraction enrichment factor such as the type and amount of the additive,pH and volume ratio of donor phase and acceptor phase,extraction time,salt-out effect and matrix effect were optimized.Under the optimal extraction conditions(organic liquid membrane phase:[C8MIM][PF6]with 14%TOPO(w/v),donor phase:4 mL,pH 4.5 KH2PO4 with 2M Na2SO4,acceptor phase:25μL,pH 13 NaOH,extraction time:8 H),low detection limits(0.1-0.4μg/L,RSD≤5%) and good linear range(1-2000 ng/mL,r2≥0.999) were obtained for all the analytes.The presence of humic acid (0-25 mg/L dissolved organic carbon) and bovine serum albumin(0-100μg/mL) had no significant effect on the extraction efficiency.Good spike recoveries over the range of 82.2-103.2%were obtained when applying the proposed method on five real environmental water samples.These results indicated that this present method was very sensitive and reliable with good repeatabilities and excellent clean-up in water samples.The proposed method confirmed hollow fiber supported ionic liquid membrane based LPME to be robust to monitoring trace levels of sulfadiazine, sulfamerazine,sulfamethazine,sulfadimethoxine and sulfamethoxazole in aqueous samples.
|
PDF Full Text Request