以DMPS作為複合劑及使用石墨式原子吸光法測定底泥中總汞之研究

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Title:	以DMPS作為複合劑及使用石墨式原子吸光法測定底泥中總汞之研究
Other Titles:	Determination of Total Mercury in Sediment by Graphite -Furnace Atomic Absorption Spectrophotometry using 2,3-Dimercaptopropane-1-sulfonate (DMPS) as a Complexing Agent
Authors:	徐明德 Hsu, Ming-Te
Contributors:	郭茂松 Kuo, Mao-Sung 東海大學環境科學與工程學系
Keywords:	底泥;石墨式原子吸光儀;微波消化;DMPS sediment;GFAAS;microwave;DMPS
Date:	2004
Issue Date:	2011-05-19T07:43:47Z (UTC)
Abstract:	本研究取50 mg已經乾燥的底泥樣品，放入7 mL鐵氟龍瓶中，加入700 μL王水及50 μL氫氟酸後，進行微波消化（80℃，10分鐘）將底泥中的總汞萃出。以氫氧化鈉溶液（1 N）調整消化混合物之pH值至6.5-7.0，經過濾移除底泥殘渣後，加入醋酸鈉緩衝溶液（1 mmol）及複合劑（DMPS，1.2x10-3 M 500 μL），與汞反應約1小時使生成汞-DMPS之複合物，然後流經兩個自製串聯之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0.50 mL。取出部份（50 µL）注入石墨式原子吸光儀（GFAAS），測定汞的含量。使用本方法測得四種底泥參考標準樣品GBW 07305〔certified value 100±20 (ng/g)〕之值為96±2.4 (ng/g)；CRM 016-050〔certified value 110±40 (ng/g)〕之值為107.2±2.8 (ng/g)；GBW 07311〔certified value 72±14 (ng/g)〕之值為61.8±3.0 (ng/g)；BCR CRM 580〔certified value 132±3 (μg/g)〕，經稀釋1000倍後，測得底泥中汞的濃度為6.62±0.09 ng，換算後，相當於132.4±1.8 (μg/g)，表示本方法的準確度良好，添加回收率為96.7-101.2%。本方法偵測極限（MDL, 3σ）之絕對量為0.34 ng Hg，相當於濃度為6.8 (ng/g) Hg，線性可達310 (ng/g)。使用本方法測定四個台灣中部地區河川的底泥樣品，其濃度介於33.6-67.2 (ng/g)，添加回收率為97.1-102.1%，RSD< 4.7% （n=3），以加拿大最嚴格的規範（< 100 ng/g）為例，這四條河川的底泥尚屬於未受到污染的程度。本方法應可應用於底泥中總汞之測定。 In this thesis, an amount (50 mg) of dried sediment sample was digested with a mixture of aqua regia (700 μL) and hydrofluoric acid (50 μL) at 80℃ for 10 min in a 7-mL Teflon microreaction vessel. After digestion, the pH of the acidic sediment mixture was adjusted to 6.5-7.0 by NaOH. The sediment residue was removed by passing the mixture through a 0.45 μm filter membrane. Appropriate amounts of 2,3-dimercaptopropane-1-sulfonate (DMPS) and sodium acetate buffer（pH=6.0）were added to the filtrate to form a mercury-DMPS complex. The complex was preconcentrated on two home-made C18 cartridges in series, and then each cartridge was eluted with methanol and adjusted to 0.50 mL. A portion （50 μL）was introduced into a graphite cuvette and then measured by GFAAS (λ=253.7 nm).The peak heights in absorbance were used for a quantitative analysis. The observed values [96.0±2.4 (ng/g), 107.2±2.8 (ng/g), 61.8±3.0 (ng/g), and 132.4±1.8 (μg/g)] of total Hg in four sediment certified reference materials (GBW 07305, CRM 016-050, GBW 07311, and BCR CRM 580 ) were in good agreement with the certified values [100±20 (ng/g), 110±40 (ng/g), 72±14 (ng/g), and 132±3 (μg/g) Hg, respectively ].The method detection limit (MDL, 3σ) was 6.8 (ng/g)；the calibration graph was linear up to 310 (ng/g). Recoveries of 96.7-101.2% were obtained by spiking known amounts of mercury to the four CRM sediments. Four real sediment samples (33.6-67.2 ng/g) collected from four rivers near Taichung were analyzed, and the recoveries were 97.1-102.1% with RSD (n=3) < 4.7%. These four real samples are classified as unpolluted sediments (<100 ng/g) according to Canadian regulation. The proposed method can be applied to the measurement of total mercury in sediment samples.
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