硒试剂光度法测定钢铁及加硒碘盐中的微量硒

DETERMINATION OF TRACE SELENIUM IN STEEL AND IRON AND SALT ADDED IODINE AND SELENIUM USING 3,3'-DIAMINOBENZIDINE AS SELENIUM(Ⅳ) ORGANIC REAGANT BY SPECTROPHOTOMETRY

以3,3′-二氨基联苯胺(硒试剂)作显色剂,加足量乙二胺四乙酸二钠(EDTA)掩蔽铁等金属离子,在pH为2～3的甲酸介质中显色,在pH为6～7时,用甲苯萃取硒(Ⅳ)-硒试剂络合物。当溶液中的硒(Ⅳ)含量大于20μg/10mL时,不用萃取硒(Ⅳ)-硒试剂络合物,直接测定。该方法用于钢铁及加硒碘盐中微量硒的测定,结果满意。

3,3'-diaminobenzidine is used as selenium(Ⅳ) organic reagant, a moderate amount of ethylenediamine disodium tetrac-etate(EDTA)is added to mask the polyvalent metals such as iron. The yellow seleninum compound is developed at pH 2 to 3 and quantitatively extracted by toluene at pH 6 to 7. When the content of selenium(Ⅳ) is over 20μg/10 mL, no extraction is needed and the selenium (Ⅳ) content can be determined directly. This method has been applied in the determination of trace selenium in steel and iron and salt added iodine and selenium with satisfactory results.