| Summary: | 碩士 === 東海大學 === 環境科學系 === 82 === Two parts are included in this thesis. In the first part, a comparative study for the determination of formaldehyde in water was investigated by colorimetry, high performance liquid chromatography(HPLC) and gas chromatography(GC). A solution of 0.050%(w/v) p-aminoazobenzene and 0.10%(w/v) sodium salt of chromotropic acid, respectively, was used as a coloring reagent in colorimetry. A 0.10M of 2,4-pentanedione in ammonium acetate buffer at pH 6.0 was used as a fluorescent derivative reagent for formaldehyde in HPLC and a solution of 0.0050%(w/v)N-benzylethanolamine in isoocatane was used as a derivative reagent for formaldehyde in GC(FID). The linear ranges obtained by these methods were(0.38-12.7)μg/8.40mL; (0.40-31.5)μg/3.00mL; (0.45-60.0)μg/1.00mL and (0.080-0.396)μg/20.0μL, respectively. The accuracy of these methods was tested with Chem Service #0229 formaldehyde standard solution and the results of 100-101%, 102-103%, 99.7-101%, and 101-103% were obtained with precision values of ±4.3%, ±4.0%, ±2.0%, and ±2.6%, respectively. The recoveries for real samples(such as, an industrial discharged water before treatment, a groundwater in the Blackfoot Disease regions and at Tunghai University) obtained by these methods were in the ranges of 99.2-102%, 98.3-103%, 88.8-102%, and 98.0-99.8%, respectively. The concentrations of formaldehyde in the industrial discharged water determined by these methods were in the range of 232-239mg/L, while that in Blackfoot Disease region and at Tunghai University were below the method detection limits (0.030, 0.044, 0.211 and 0.021mg/L) respectively. There are advantages and disadvantages among these methods investigated and one can select an appropriate method for the determination of formaldehyde in water.
In the second part, after the pH of water sample (such as, ground-water, SRM 1643c water standard, or QC HPS#290608 wastewater) was adjusted to about 5.5 with NH4OH, appropriate amounts of matrix modifiers containing Ni/ 2,3-dimeracpto-1-propanesulfonate (DMPS)/ammonium acetate buffer (pH5.5) in water were added. An aliquot of the mixture (20.0μL, containing 10μg Ni and 0.17μg DMPS) was introduced into a graphite tube cuvette and was heated according to a temperature program. The DMPS besides nickel enhanced the sensitivity for arsenic probably due to the hydrogen bonding between H2AsO4- and DMPS. By using this proposed method, a linear range of total As from 1.50 up to at least 92.5μg/L was obtained. The accuracy and the applicability of this method were tested with SRM 1643c synthetic water standard and QC wasterwater (HPS#290608), respectively, and the results of 96.5-101% and 101-102% were obtained with precision values of ±3.3% and ±4.0%. A real sample from one of the Blackfoot Disease regions at Pu-Tai(Chia-Yi, Taiwan) was determined by this proposed method and the concentration of 651±5μg/L was obtained. The method detection limit (3σ) after dilution 250-folds from this sample was determined as 1.0±0.2μg/L. The results obtained by this proposed method were better (such as, a wider linear range, better accuracy, and cost less) than those obtained by the traditional method which uses Ni and Pd in 0.2%(v/v)HNO3 as a matrix modifier. This method can be applied easily and accurately to the determination of total As in drinking water and groundwater.
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