本篇取0.070 g土壤樣品，放入小鐵氟龍瓶(7 mL)中，加入750 μL王水及75 μL氫氟酸後，於80℃微波加熱(約60 W)消化10分鐘。消化後之混合物，以NaOH(1 N)調整其pH值至6.0-7.0，過濾後，將濾液流經一個淨化用自製之C18 cartridge。在流出液中，加入適量醋酸鈉緩衝溶液及複合劑(DMPS)，與汞反應約1小時後，流經兩個串聯自製之C18 cartridge，使汞-DMPS的複合物滯留於C18 cartridge上。每個cartridge各用甲醇洗出複合物，並定量至1.00 mL。取出50 µL注入石墨式原子吸光儀(GFAAS)，測定汞的含量。在探討各項變數時，本實驗使用0.070 g土壤標準樣品(GBW 07404)，比較其相對吸收峰高度，作為條件選擇之依據。 使用檢量線法，測得土壤標準樣品（GBW 07404）中汞的濃度為586±19 (ng/g)，可落在certified value [590±80 (ng/g)]之範圍內，表示本方法之準確度良好。本方法偵測極限(MDL, 3σ)之絕對量為0.45 ng Hg，相當於濃度為6.4 (ng/g) Hg，線性範圍可達1.4 µg/g。於土壤標準品中(約含有40 ng Hg)添加20-60 ng甲基汞或無機汞，測得其回收率為97.6-99.6%。本方法應可應用於我國土壤總汞之測定。 In this thesis, an amount (70 mg) of soil sample was digested with a mixture of aqua regia (750 µL) and hydrofluoric acid (75 µL) at 80℃ for 10 min in a 7-mL Teflon microreaction vessel. After digestion, the pH of the acidic soil mixture was adjusted to 6.0-7.0 by NaOH. After filtration, the filtrate passed through a clean-up C18 cartridge. To the eluate, 2,3-dimercaptopropane-1-sulfonate (DMPS) and sodium acetate buffer (pH=6.0) were added to form a mercury-DMPS complex. This complex was preconcentrated on two home-made C18 cartridges in series, and each cartridge was eluted with methanol and adjusted to 1.00 mL. A portion (50 µL) was introduced into a graphite cuvette and then atomized according to a temperature program. Each parameter of experimental conditions was varied successively by using 0.070 g of a soil certified reference material (GBW 07404). The relatively large absorbance in peak height was chosen among the variables. The method detection limit (MDL, 3σ) was 6.4 (ng/g)；the calibration graph was linear up to 1.4 (µg/g). The observed values [586±19 (ng/g), n=8] of Hg in a soil certified reference material (CRM, GBW 07404) were in good agreement with the certified value [590±80 (ng/g)Hg]. Recoveries of 97.6-99.6% were obtained by spiking 20.0-60.0 ng of mercury (CH3Hg+ or Hg2+) to the Soil CRM GBW 07404.
