海水中微量金屬元素濃縮問題的探討第二部分：以Chelex-100鉗合樹脂－石墨爐原子吸收光譜法測定海水中溶解性鎘銅鎳鋅鈷元素

Study on the Pre-concentration Column for the Determination of Trace Metals in Seawater Part 2. Application of Chelex-100 Column and Graphite Furnace Atomic Absorption Spectrometry on the Determination of Dissolved Cd, Cu, Ni,Zn and Co in Seawater

鍾仕偉(S. W. Chung) ； 白書禎(S. C. Pai) ； 陳秋妏(C. W. Chen) ； 董正釱(C. Dong) ； 歐錫祺(H. C. Ou)

《化學》 55卷1期 (1997/03) Pp. 29-36

https://doi.org/10.6623/chem.1997004

摘要

本研究乃針對海水中微量金屬元素的濃縮與測定方法作一探討。利用鉗合樹脂濃縮法濃縮海水中的微量金屬元素，如鎘、銅、鎳、鋅與鈷。同時以原子吸收光譜儀測定之。在作法上，外洋海水採樣後(體積1250毫升)以小於4 mL/min之流速通過一Chelex-100濃縮裝置，最後以10毫升2N的硝酸回收之，如此則達到濃縮125倍的目的，此濃縮倍數可以有效的測定海水中的鎘，銅，鎳與鋅元素。但對於超低濃度的鈷元素則需將2N硝酸沖堤液於燒杯中烘乾而後以稀硝酸再溶解以達到二次濃縮的目的，最後則是在原子吸收光譜儀之石墨管上連續注入測定之。實驗結果，添加0.1-1 ppb 的四種微量金屬元素於空白海水中， 濃縮後所得之回收率介於97-105%之間，而添加1.6 -3.1 ppt 的鈷元素於海水中再經過三階段的濃縮步驟所得之回收率介於99-104% 。以CASS-1，NASS-2 與NASS-4標準海水測試之結果，皆得到令人滿意之結果。

關鍵字

重金屬 ； 預濃縮 ； Chelex-100鉗合樹脂 ； 原子吸收光譜法

並列摘要

The experimental conditions of operating the Chelex-100 column for the pre-concentration of trace amounts of Cd, Cu , Ni, Zn, and Co in natural seawater have been optimized by a proposed exponental model. Seawater (1.25L) were allowed to pass through the Chelex-100 column at a flow rate of no more than 4 mL/min and the metals were recovered by eluting with nitric acid. The concentration factor obtained was 125 folds , which provided enough sensitivity for detecting Cd, Cu, Ni and Zn at their naturallevels (0.1-1 ppb) using graphite furnace atomic absorption spectrometry. Good recoveries (97-105%) were found for those four elements. However, for Co analysis (natural concentration range 1-7 ppt) a second evaporation step was continued to further reduce the volume of the column concentrate from 10 mL to 2 mL. The final yield was deposited repetitively onto the graphite tube in order to enhence the sensitivity. With these modifications the concentration of Co in seawater was determined even the concentration was as low as 0.001-0.003 ppb. The method was checked by measuring CASS-1, NASS-2 , and NASS-4 certified reference seawaters and the results were satisfactory.

並列關鍵字

Trace Metals ； Pre-concentration ； Chelex-100 Chelating Ion-exchange Resin ； Atomic Absorption Spectrometry