Studies On New Sample Pretreatment Techniques For Applications On Electronical And Environmental Analysis

Sample preparation is very important in sample analysis in all aspects of chemical, biological, materials, and surface analysis. It is often the bottleneck in a measurement process, as they tend to be slow and labor-intensive. With the diversity of the sample , many of the traditional sample preparation methods and techniques have been further improved; new approaches and technologies have emerged recently. Notably among recent developments are fast, effective, simple, green methods and techniques. This dissertation reviews a variety of sample preparation techniques, applied to the determination of electronic products and environmental samples. It is composed of four parts.In the first part, the principles and characteristics of some important pretreatment methods in the analysis are reviewed, including solvent extraction, solid phase extraction, gas extraction, membrane separation, thermal desorption and so on., The goal of this dissertation is deduced to develop some new sample pretreatment methods, which are applied to the environmental analysis using chromatography.In the second part, the oxygen bomb combustion - ion chromatography method for the determination of halogen in electronic products is proposed. The samples are oxidized by combustion in a closed system. Halogen containing compounds are converted to chloride and bromide, respectively, which are later absorbed in an absorption solution. Ion chromatography is used for the determination of halides in the absorption solution. The detection limits of the ions were 5.6 and 20.5μg/L, respectively.In the third part, the conventional method in determination of acetic acid esters is improved. Acetic acid esters are collected by activated carbon tubes, and organic compounds are extracted by methanol, instead of xx used conventionally. Gas chromatography (GC) with hydrogen flame ionization detector (FID) is used for the measurement of the esters. The method is accurate and suitable for the rapid determination of acetic acid esters in ambient air.In the fourth part, hydrocarbons (C2 ~ C8) in the gas sample are enriched by Tenax tube and analyzed simultaneously by GC with on-line thermal desorption apparatus. Non-methane hydrocarbon gases enriched by pyrolysis are directly detected by GC-FID with on-line thermal desorption apparatus, and a total chromatographic peak is appeared. The retention time of hexane is used for the quantitation of total non-methane hydrocarbon. The method is simple, fast and reproducible.