Study On The Method Development And Its Application Of Inorganic Selenium Species In Water Samples

As an important element to human health,the study of selenium and its morphology has been the research hotspots in the field of elemental speciation analysis.At present,the commonly used method for selenium speciation is mainly to combine various chromatographic techniques with high-sensitivity element detectors.Such as gas chromatography(GC),liquid chromatography(LC),capillary electrophoresis(CE),with atomic fluorescence spectroscopy(AFS),inductively coupled plasma mass spectrometry(ICPMS)combined to determine the form of selenium.Selenium element mainly exists as inorganic species(Se(?),Se(?))and it's content is below 10-11.Studies have shown that the toxicity of inorganic selenium is much greater than that of organic selenium(about 40 times).In this paper,tetrabutylammonium bromide(TBAB)modified activated carbon(AC)was used as a filler to prepare a solid phase extraction(SPE)column.Se(?)and Se(?)were enriched in water and eluted with HCl.After desorption,combined with high resolution liquid chromatography and highly sensitive hydride generation atomic fluorescence spectrometry(HGAFS)technology,Se(?)and Se(?)analysis methods were established.The main results were as follow:The origin,physical and chemical properties of selenium and its species,as well as its effects on human body were introduced in Chapter 1.In Chapter 2,the PRP-X100 anion exchange column is used as a separation column,and the thiourea on-line pre-reduction of Se(?)is achieved by heating in an oil bath under acidic conditions.An analytical method for the determination of two inorganic selenium forms by HPLC-HGAFS technique was established.Under the optimal optimization conditions,the separation of two inorganic selenium forms was achieved within 8 min.The detection of limits of Se(?)and Se(?)were 1.44 ?g/L(DL,3?)and 3.00 ?g/L(DL,3a),respectively.A linear relationship of Se(?)and Se(?)were observed within the concentration range of 4.8 to 100.0 ?g/Land 10.0 to 100.0 ?g/L.Precision with relative standard deviations(RSD)were 3.6%(Se(?),5?g/L,n=7)and 3.0%(Se(?),10 ?g/L,n=7).The method could be applied to analyse Se(?)and Se(?)in real water samples.In Chapter 3,TBAB as modifier to fabricate activated carbon(AC)was selected with magnetic stirring at room temperature.Then modified AC was packed into a 1000?L SPE column to enrich Se(?)and Se(?)in water samples.The SPE column has a maximum enrichment factor of 250 times for two inorganic selenium forms.Combing the SPE with HPLC-HGAFS system,a novel procedure for ultra-trace level of Se(?)and Se(?)was developed.Under the optimal condition,the linear concentration range of application were 0.02-1.00 ?g/L of Se(?)and 0.04-1.00 ?g/L of Se(?),with relative standard deviations of 3.7%(Se(?),0.04 ?g/L,n=7)and 4.4%(Se(?),0.04 ?g/L,n=7),and detection of limits of Se(?)and Se(?)were 0.0069 ?g/L(DL,3?)and 0.0081 ?g/L(DL,3a).This method has successfully achieved for the determination of Se(?)and Se(?)in selenium-enriched mineral water in a certain area of Jiangxi Province.In Chapter 4,an analytical method using HPLC-HGAFS with an ultraviolet lamp for pre-reduction of Se(?)and homemade SPE column for Se(?)and Se(?)enrichment.In this system,Se(VI)was online reduced by Potassium iodide(KI)under the irradiation by ultraviolet lamp.Under the optimal condition,the calibration graph for Se(?)and Se(?)were linear over the range of 0.011-1.00 ?g/L and 0.015-1.00?g/L,with RSD of 2.2%(Se(?),0.03 ?g/L,n.=7)and 4.2%(Se(?),0.03 ?g/L,n=7).Chapter 5 summarizes the main contents of this study and looks forward to future research.