| Abstract: | 本論文分為兩部分，第一部分是使用比色法、液相及氣相層析法測定水中甲醛之研究，第二部分是使用石墨電熱式原子吸光法直接測定地下水中總砷之研究。 在第一部分比色法中，分別以0.050%(w/v)p-aminoazobenzene及0.10%(w/v)chromotropic acid之鈉鹽作為顯色劑；在液相層析法時，以0.10M2,4-pentanedione配在pH=6.0之ammonium acetate中，作為螢光衍生試劑；在氣相層析法時，以0.005%(w/v)N-benzylethanolamine配在isooctane中，作為衍生試劑。由以上四種方法所得之線性範圍分別為(0.38-12.7μg)/8.40mL水樣；(0.40-31.50μg)/3.00mL水樣；(0.45-60.0μg)/1.00mL水樣；(0.0080-0.396μg)/20.0μL水樣。以Chem Service甲醛溶液檢測準確度之結果分別為100-101%、（精密度為±4.3%）；102-103%、（精密度為±4.0%）；99.7-101%、（精密度為±2.0%）；101-103%、（精密度為±2.6%）。在真實水樣中（包括工業區未處理前的排放水樣、烏腳病地區及東海大學地下水水樣），作回收率測試時，分別得到99.2-102%、98.3-103%、88.8-102%及98.0-99.8%。由此四種方法測得工業區未處理前的排放水樣中之甲醛濃度均在232-239mg/L；烏腳病地區及東海大學地下水水樣中甲醛濃度均低於方法偵測極限（分別為0.030、0.044、0.211及0.021mg/L）。這四種方法在儀器設備、藥品費用、操作時間、安全性、線性範圍等方面各有優缺點，因此實驗室可視其需要，選擇合適的方法進行水中之甲醛之測定。 在第二部分時，先用NH4OH將已酸化含砷的水樣（如：地下水；標準參考樣品SRM1643c；或品管樣品HPS#290608）之pH值調至約5.5，加入適量配在水中之基質修飾劑（Ni/2,3-dimercapto-1-propane-sulfonate(DMPS)/ammonium acetate buffer(pH=5.5)）後，取出20.0μL水樣（內含10μg Ni 及0.17μDMPS）注入石墨管中，依加溫程式加熱。在使用的基質修飾劑中，除了一般常用的Ni可提高本方法之靈敏度（形成ion pair : Ni(H2O)6 2+| H2AsO4 -）外，DMPS亦可能藉由氫鍵（hydrogen bonidng）與H2AsO4 -結合成〔DMPS-, H2AsO4-〕之複合物，有助於水中總砷之測定。使用本方法測得水中總砷檢量線之線性範圍由1.50至92.5μ，用HPS #290608砷溶液檢測檢量線之適用性為101-102%（精密度為±4.0%）。以SRM 1643c砷溶液測得準確度為96.5-101%（精密度為±3.3%）。使用本方法測得台灣烏腳病地區（嘉義縣布袋鄉）一口深井水中總砷濃度為651±5μg/L，將此水樣稀釋250倍後，測得方法偵測極限（Method Detection Limit, MLD, 3σ）為（1.0±0.2）μg/L。 由本方法所得之線性範圍及準確度均較傳統酸性溶液法（Ni/Pd in 0.2%(v/v)HNO3）的2.10-70.0μ/g/L及65.4-89.3%為佳，且不需使用酸性溶液，可節省藥品費用。由以上結果可知，本方法操作簡單，可應用於直測地下水及飲用水中之總砷。
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. |
