EDTAによる溶解とDDTCとの錯体形成により汚でい中のクロム(VI)を直接溶媒に抽出し定量する方法
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概要
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It has been considered verv difficult to make a quantitative analysis by extracting chromium(VI) {Cr(VI)} throughly, because sludge contains slightly soluble chromates together with organic substances or reducible materials. The method proposed here is just to solve the above mentioned problem and charactarized by the following process (i) and (ii). (i) Dissolve slightly soluble chromates by treating the sample with EDTA in an ammoniacal alkaline medium, and then excess EDTA is masked with calcium. As excess EDTA impedes the formation of Cr(III)-DDTC, the EDTA must be masked by adding calcium to the sample slurry prior to neutralization. (ii) Allow to react the dissolved Cr(VI) with sodium diethyldithiocarbamate(DDTC) at pH 5〜7, and then extract the formed Cr(III)-DDTC into methylisobutylketone(MIBK) immediately. It is necessary for DDTC and MIBK to be made to co-exist with the sample slurry in order to proceed with this process(ii) more effectively. Procedure: Transfer the finely pulverized sample, containing (5〜200) μg as Cr(VI), to separating funnel in which 20 ml of 10% DDTC solution is contained. Add 20 ml of 0.05 M EDTA solution and 10 ml of concentrate ammonia water, and then shake it for ten minutes. Add 25 ml of 0.05 M calcium chloride solution and mix. Adjust the pH of the mixture to 5 by adding acetic acid-ammonium acetate buffer solution. Shake the mixture for a few minutes with (50〜100)ml MIBK. Filter the residue on a small filter paper and then allow the phases to separate. Finally evaporate the solvent after separating this organic layer, and decompose the residue with nitric acid. The solution obtained thereby is to bc analyzed by atomic absorption spectrometry. This method is applicable to practical use of Cr(VI) in environmental matters.
- 社団法人日本分析化学会の論文
- 1976-08-10
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関連論文
- クロム(III)を含む汚でい中クロム(VI)の原子吸光定量法 : EDTAによる溶解とジエチルジチオカルバミン酸ナトリウムとの錯体形成を用いた直接溶媒抽出法
- EDTAによる溶解とDDTCとの錯体形成により汚でい中のクロム(VI)を直接溶媒に抽出し定量する方法