| Summary: | 碩士 === 中原大學 === 化學研究所 === 89 ===
ABSTRACT
The method based on combination of the technique of headspace solid phase microextraction (HSSPME) to that of attenuated total reflectance (ATR) infrared (IR) sensing probe was developed toward detection of volatile compounds in aqueous solutions. This method can effectively eliminated the problems associated in soaking type of probes, such as pilling hydrophobic film from the sensing elements and the variation of analytical signals caused by the matrix composition. A specially designed sample cell was proposed for this purpose, which allowed to examine the performance of HSSPME/ATR-IR method and its related factors, such as the effect of agitation, headspace volume, sample volume, and temperature. Results showed that a fast speed was observed for the detection of VOCs in the HSSPME/ATR-IR method. The typical time for reaching the maximum analytical signals was around 20 minutes. Much stronger signals were obtained by applying agitation to the aqueous solution and it influences more effectively for lower volatility compounds. The headspace volume influenced the analytical signals strongly for low volatility compounds, but was only slight for highly volatile compounds. An increase in the sample volume can result in stronger analytical signals but limited to a certain signal. By examining five VOCs with different volatility, the obtained linear regression coefficients (R-square) on their standard curves in the concentration range of 5 to 200 ppm were higher than 0.99. The typical detection limit using this method was around a few hundred ppb. The absorbed probe regeneration was highly efficient and typically the regeneration time was shorter than five minutes.
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