| Summary: | 碩士 === 淡江大學 === 水資源及環境工程學系 === 87 === Ⅰ. Fast and effective for determination of trihalomethanes in tap water.
Total trihalomethanes (TTHMs) including chloroform (CHCl3), bromodichloromethane (CHBrCl2), dibromochloromethane (CHBr2Cl) and bromoform (CHBr3) are the main by-products of water chlorination when the halogen-containing disinfectants interact with natural organic matter in water. The traditional methods for the analysis of chlorination disinfection by product (DBPs) were based on solvent extraction. These methods are time - and labor — intensive and require the use of hazardous organic solvents.
Solid-phase microextraction (SPME) is a simple, fast and sensitive method of sample preparation that is also solvent-free. The aim of this study was to investigate the use of SPME coupling with gas chromatography (GC) for determination of chlorination DBPs in tap water. The four factors of mix level orthogonal array design were used in this study to obtain the optimized conditions for the headspace absorption of 100μm poly(dimethylsiloxane) fiber in SPME device : absorption time, 20mins; stirring speed, 600rpm; temperature, 40℃; air/liquid ratio, 15/5 (v/v).
The method determination limit (MDL) of this study are:CHCl3 0.979, CHBrCl2 0.123, CHBr2Cl 0.125, CHBr3 0.115 ng/mL, respectively. The MDL of chloroform in this study was higher than that of standard method, and the MDL of the other three compounds were closed to that of standard method.
Headspace SPME-GC were applied in the analyses of the tapwaters and the results showed that the concentrations of TTHMs in all the samples studied were less than 100ng/mL , as well as the samples from the different unit in water treatment plant. It is also confirmed that the THMs of the effluent from plant were produced in the process of the chlorination.
Ⅱ. Comparison of microwave extraction and traditional method for the determination of heavy metal in soil.
The pollution by heavy metals in soils are very severe in Taiwan, such as the Tao-Yuan by Cd and Pb, the Chung-Hua by Cd and the Kao-Hsung by Hg. The traditional method for the analysis of heavy metals in soils was time-cosuming because the sample was shaked for 1 hour. Microwave extraction method is new method, it could quickly extract in few minute, so this method is timesaving.
The aims of this study are to extract Cu, Pb, Zn and Cd in soils by open focus microwave digestion system, to determine these heavy metals by atomic absorption spectrometric ,and to compare the tarditional method with microwave extraction. The four factors of mix level orthogonal array design were used in microwave extract to obtain the optimized microwave extraction conditions for all metals, for example, the best microwave extraction conditions for Cu were as following: microwave power 270W, extraction time 1.5min, HCl concentration 0.05M and solid/liquid ratio 1/20.
We have applied this method to the sample that were obtained from five areas: Taipei county, Tao-Yuan county, and Chung-Hua county(3 areas). The results showed, this method was comparable with the traditional methods.
|
|---|
