Taher M A, Bansal H, Puri B K
Department of Chemistry, Shahid Bahonar University, Kerman, Iran.
Ann Chim. 2001 Sep-Oct;91(9-10):649-58.
Cobalt is quantitatively retained as cobalt-2-nitroso-4-sulfonic acid (nitros-S)-tetradecyldimethylbenzylammonium (TDBA+) ion-pair complex on microcrystalline naphthalene in the pH range 6.2-9.0 from a large volume of its aqueous solution of various complex samples. After filtration, the solid mass consisting of cobalt complex and naphthalene is dissolved in 5 ml of dimethylformamide (DMF) and the metal is determined by flame atomic absorption spectrometry (FAAS). Cobalt complex can alternatively be quantitatively adsorbed on tetradecyldimethylbenzylammonium chloride-naphthalene adsorbent packed in a column and determined similarly. The calibration curve is linear over the concentration range 0.2-11.5 micrograms of cobalt in 5 ml of the final DMF solution. In this case, 0.2 microgram of cobalt may be concentrated in a column from 250 ml of aqueous sample where its concentration is as low as 0.8 ng/ml. Eight replicate determinations of 3.0 micrograms of cobalt in the final DMF solution give a mean absorbance of 0.045 with a relative standard deviation of 1.8%. The sensitivity for 1% absorption is 59 ng/ml. The interference of a large number of anions and cations on the determination of cobalt has been studied and the optimum conditions developed utilized for its trace determination in various alloys and biological samples. The method may also be used for the determination of cobalt in some environmental samples.
在pH值为6.2 - 9.0的条件下，钴以钴 - 2 - 亚硝基 - 4 - 磺酸（亚硝基 - S）- 十四烷基二甲基苄基铵（TDBA⁺）离子对络合物的形式定量保留在微晶萘上，该微晶萘来自各种复杂样品的大量水溶液。过滤后，由钴络合物和萘组成的固体物质溶解于5毫升二甲基甲酰胺（DMF）中，然后通过火焰原子吸收光谱法（FAAS）测定金属含量。钴络合物也可以定量吸附在填充于柱中的氯化十四烷基二甲基苄基铵 - 萘吸附剂上，并进行类似的测定。在5毫升最终的DMF溶液中，钴的浓度范围为0.2 - 11.5微克时，校准曲线呈线性。在这种情况下，0.2微克的钴可以从250毫升浓度低至0.8纳克/毫升的水样中富集到柱中。对最终DMF溶液中3.0微克钴进行八次重复测定，平均吸光度为0.045，相对标准偏差为1.8%。1%吸收的灵敏度为59纳克/毫升。研究了大量阴离子和阳离子对钴测定的干扰，并制定了最佳条件用于各种合金和生物样品中钴的痕量测定。该方法也可用于某些环境样品中钴的测定。
