| Sample pretreatment plays an important role in the field of analytical chemistry.Especially for trace levels of analytes in complex matrix, a successful performance of theanalytical procedure depends mainly on the sample preparation step. Taking intoconsideration of environmental protection and analysis cost, the traditional samplepretreatment methods tend to be miniaturized and solvent-free. Under this circumstance,dispersive liquid-liquid microextraction (DLLME) has come into being, which is amicrominiaturized LLE mode having many advantages, such as simple operation, highaccuracy, low toxicity and environment friendly. DLLME has quickly gained much moreattention in analytical chemistry field immediately after its appearance. To overcome theshortages that exist in the previously reported sample preparation methods for environmentalestrogen compounds, such as bisphenol A and phthalate ester, this thesis focuses ondeveloping novel procedures by using DLLME followed by high performance liquidchromatography for the determination of estrogen compounds of interest. The main contentsare presented as follows:1. A novel method for the determination of the migration of bisphenol A (BPA) fromplastic water bottles has been developed by using dispersive liquid-liquid microextraction(DLLME) followed by high performance liquid chromatography for compliance with theregulatory specific migration limit. DLLME experimental parameters including the type andvolume of extractants and dispersers, the sample solution pH, addition of salt, extraction timeand temperature were examined and optimized. Under the optimum conditions, averagerecovery rates for the real samples varied from82%to98%, with the relative standarddeviations (RSD) less than3.6%. The method offered excellent linearity over a range of0.2~20μg/L with correlation coefficient (r=0.9999). Intra-day and inter-day repeatabilityexpressed as%RSD were3.9%and6.9%, respectively. The method quantitation limit anddetection limit were0.18and0.07ng/mL, respectively. The developed method wassuccessfully applied to the determination of the migration of bisphenol A from26plasticwater bottles collected locally under the migration test conditions set by council directive82/711/EEC. The findings indicated the migration amounts from the used bottles wassignificantly higher than the new ones, and the amounts from one sample was very close to the regulatory specific migration limit and the amounts from seven samples exceeded thedaily intake limit for infants.2. A novel method for the determination of diisobutyl Phthalate (DIBP), dibutylphthalate (DBP) and butyl benzyl phthalate (BBP) in white spirits has been developed byusing dispersive liquid-liquid microextraction (DLLME) coupled with high performanceliquid chromatography by DAD detection. DLLME experimental parameters including thetype and volume of extractants and dispersers, the addition of salt, extraction time andtemperature were examined and optimized. The optimized extraction conditions were: sample,2mL of white spirit solution diluted with7mL of26%NaCl(w/v) solution; extractantmixture:120μL carbon tetrachloride: acetonitrile (1:1, v/v), extraction time,5min. Themethod offered excellent linearity over a range of1~500ng/mL with correlation coefficientr>0.99. The detection limits were in the range of0.3-0.8ng/mL. The enrichment factorsvaried from92to102. Intra-day and inter-day repeatability values expressed as relativestandard deviation were in the range of1.3%-2.8%,2.0%-4.7%(n=6), respectively. Thedeveloped method was applied to the determination of the phthalate esters in31white spirits,and from17out of it the amount of DBP exceeded the regulation limit. The average recoveryrates ranged from92.5%to111.2%. Compared to the previous methods, the feature of thenew procedure lies in its simpler sample preparation, less organic solvent consumption andhigher sensitivity. |
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