| The social and technological activities of human being have caused serious environmental pollution. Among the various pollutants, heavy metal species have attracted extensive attentions attributed to their toxicity. and this has been a worldwide problem. In this respect, it is highly necessary to provide timely warning of the accurate information about heavy metal accumulation in biological and environmental samples.It is an important scientific issue to obtain useful information about the targets in complex sample matrixes. However, in real sample analysis, the presence of complex sample matrixes frequently blocks the determination of target species. In addition, in many cases the concentration of target is too low to be accurately quantified. Therefore, it is very often necessary to perform appropriate sample pretreatment by isolating the target from the sample matrixes, at the same time, preconcentration of the target species can be achieved. The present sample pretreatment theories and techniques are. however, not sufficient for various real sample matrixes. Thus, it is highly desrired to develop new theories and technologies of sample pretreatment, i.e., separation and preconcentration, in combination with suitable detection protocols.Solid phase extraction is one of the most important sample pretreatment techniques which can provide high enrichment factors. It has some distinct featutes such as low sample and reagent consumption and thus low cost, ease of operation and automation. In this field, it is still highly desirable to develop novel adsorbent materials or modify the existing materials by introducing/immobilizing appropriate functional grupos in order to achieve better performances on the extraction of target species.The present work aims at investigating novel solid phase extraction techniques based on flow injection/sequential injection, by developing new adsorbent material and sample pretreatment methodologies for trace metal species. In addition to use these methods for the analysis of heavy metals in biological and environmental sample matrixes by hyphenating the solid phase extraction protocols with detection by atomic spectrometry.Chapter1discussed the state-of-the-art progresses of solid phase extraction techniques and their applications in the saparation/preconcentraion as well as speciation of heavy metal species in various samples.In chapter2ã€the separation and preconcentration of bismuth was facilitated by employing a novel sequential injection system incorporating a mini-column packed with bamboo carbon followed by detection with hydride generation atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry. The present system has been validated by analyzing a certified reference material of river sediment (CRM320), and spiking recovery of bismuth in human whole blood was performed by using hydride generation atomic fluorescence spectrometry. No significant difference was identified in the results of bismuth detection in blood samples by hyphenating the present solid extraction extraction system with detection by hydride generation atomic fluorescence spectrometry and inductively coupled plasma mass spectrometry.Chapter3of the thesis developed a sequential injection sample pretreatment procedure with a cellulose fibre packed micro-column as adsorbent for the separation and preconcentration of ultra-trace cadmium with detection by atomic fluorescence spectrometry. The cellulose fibre surface was used to integrate the preconcentration of cadmium, the immobilization of reducing reagent (NaBH4), the elution of cadmium and the ensuing on-surface vapor generation by reaction with hydrochloric acid. The present investigation provides a sensitive, selective and stable system for on-line separation/preconcentration of cadmium. The procedure was validated by analyzing certified reference materials of Riverine Water SLRS-4and Trace Elements in Water (GBW08608), in addition to spiking recovery in a coastal sea water.In chapter4, lanthanum hydroxide precipitate is for the first time coated onto cellulose fibre and serves as a novel sorption medium for separation and speciation of inorganic selenium. The retained selenium(â…£) was eluted from the micro-column packed with precipitate layer coated cellulose fibre and determined by atomic fluorescence spevtrometry. The elution of the retained selenium by using an alkaline medium avoids the dissolution of the precipitate for each analysis run in a routine precipitation/co-precipitation-based separation and preconcentration system, and thus, eliminates potential interfering effects for the detection or post-derivatization process arisen from the bulk of the precipitate and ensures repetitive use of the coated precipitate layer and improves its lifetime. The procedure is validated by analyzing selenium in a reference material GBW10010(rice) and a human hair sample. The procedure is further demonstrated by speciation of inorganic selenium in surface water samples by pre-reduction of selenate.In the last chapter, a novel cellulose fibre functionalized with cysteine was prepared as adsorbent for the collection of mercury, and a procedure for separation and preconcentraton of mercury was developed by coupling with vapor generation atomic fluorescence spectrometry. The thiol group in cysteine molecule immobilized on the cellulose fibre significantly improved the sorption capability for mercury attributed to the affinity of thiol for mercury. It is potentially feasible for the speciation of inorganic and organic mercury by coupling solid phase extraction using the present cysteine funationalized cellulose fibre with detection by atomic fluorescence spectrometry. |
