Method For Determination Of Cobalt Research Articles

Coupled redox and complex formation processes as a kinetic fluorimetric method for the determination of cobalt

A sensitive and relatively interference-free method for the kinetic determination of cobalt is described. The method is based on the slow oxidation of pyridin-2-aldehyde-2-pyridylhydrazone (PAPH) to a fluorescent product in the same medium as the complex formation with cobalt ions. The influence of reaction variables and the effect of foreign ions are discussed. Cobalt contents between 20 and 150 ng ml−1 can be determined with a relative standard deviation of 4%. The composition of the chelate species, and the stability constant of the complex have also been determined.

Spectrophotometric Determination of Cobalt(II) with Eriochrome Black T after Extraction as Methyltrioctylammonium Tetrathiocyanatocobaltate(II)

Abstract A sensitive extraction-spectrophotometrie method for determination of cobalt(II) with Eriochrome Black T is described, which involves the preliminary separation of cobalt from aqueous solution by the benzene extraction of methyltrioctylammonium tetrathiocyanatocobaltate(II). The quantitative formation of ion pair between cobalt–Eriochrome Black T complex anion and the quaternary ammonium cation is attained by shaking the resulting extract with aqueous Eriochrome Black T solution of pH 5.5–8.2. Beer’s law holds for 0.57–4.0 μg cobalt in 5 ml of the extract with the molar absorption coefficient of ε587=6.62×104 cm−1 mol−1l (Sandell sensitivity 8.90×10−4 μg cm−2). The composition of the extracted ion pair is estimated to be cobalt: Eriochrome Black T:methlytrioctylammonium ion=1:2:3.

A comparison of various methods for determination of cobalt in marine biological materials

The reliability for determination of cobalt in biological samples was studied by using various analytical methods such as atomic absorption spectrometry (AAS), absorption photometry(AP), and instrumental neutron activation analysis (INAA). The marine samples used were various kinds of shellfish which were dried at 105°C and then ashed at 500°C in an electric furnace. After the ashes were decomposed with HF, HNO3 and fuming HNO3, followed by evaporation to dryness, the residues were dissolved in dilute HCl and were analysed by AAS and AP. In the AAS method the absorbance was directly measured at 240.7 nm using air-C2H2 flame. In the AP method cobalt was first extracted into xylene with 1-nitroso-2-naphtol reagent, and then the absorbance was measured at 410 nm. In the INAA method, the ash sample and the reference standard were irradiated for 24 h at a thermal neutron flux of 5×1011 n cm-2 s-1 in the TRIGA II reactor at Rikkyo University, and after cooling for 15 days the 1332 keV gamma ray was measured by a Ge(Li) detector coupled with a multichannel pulse height analyser. The analytical results were (in μg Co/g wet tissue) : 0.49 (AAS). 0.22 (AP) and 0.21 (INAA) in Tapes philippinarum; 0.28 (AAS), 0.081 (AP) and 0.077 (INAA) in Mytilus edulis; 1.2 (AAS), 1.1 (AP), and 0.95 (INAA) in Tridacna squamosa, respectively. Values obtained by AP and INAA agreed well each other, whereas those obtained by AAS were higher than the corresponding values obtained by the former two methods. The origine of the higher values was found to be the interference by iron and calcium in the samples. The reliability of AP and INAA were confirmed by the analysis of Bovine Liver (NBS standard reference material) and standard rock samples AGV-1 and JG-1.

A polarographic method for the simultaneous determination of cobalt and nickel from acid solutions

A polarographic method for the simultaneous determination of cobalt and nickel from acid solutions

固体二酸化マンガンによる濃縮操作を用いる海水中のコバルトの分光光度定量法

海水中のコバルトの定量について操作の詳細を叙述した. この定量法は, 固体二酸化マンガンを用い吸着によって海水中の微量コバルトを濃縮する操作, 硝酸による脱著操作, 2-ニトロソ-1-ナフトールを用いる溶媒抽出操作およびニトロソR試薬による分光光度測定から成立っている. 分析の際には, コバルト-58をトレーサーとして用い, コバルトの回収率を吟味する. ここに述べた簡便なコバルトの濃縮法によって, 最少の汚染で, 比較的多量の試料を短時間内にとり扱うことができ, かくして船上および実験室で日常業務としてコバルトの分析を行なうことが可能になる.この方法による海水中のコバルトの定量の限界は20lの試水を用いた場合0.05μg/l付近にあり, 一方全量5μg Coまでの範囲で, 単一分析に対する標準偏差は0.1μg Coと推定される. この方法によって測定されるコバルトの化学型は, おそらく水和状態にある2価の灘バルトイオンであり, コロイド分散状の3価のコバルトが存在すれば, これもまた測定されると考えられる.

Colorimetric Method for Determination of Cobalt in Stainless Steel

Colorimetric Method for Determination of Cobalt in Stainless Steel

A Volumetric Method for Determination of Cobalt and Nickel

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Volumetric Method for Determination of Cobalt and NickelJ. T. Dobbins and J. P. SandersCite this: Ind. Eng. Chem. Anal. Ed. 1934, 6, 6, 459–460Publication Date (Print):November 1, 1934Publication History Published online1 May 2002Published inissue 1 November 1934https://doi.org/10.1021/ac50092a033RIGHTS & PERMISSIONSArticle Views45Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (275 KB) Get e-Alerts