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4-〔(2-吡啶)偶氮-1,3-二氨基苯(简称PADAB)及其卤代衍生物是分光光度测定微量钴的优良试剂。它的苯环上引入甲基后形成的PADAT及其卤代(特别是双卤代)衍生物,灵敏度、尤其是选择性更有提高。文献指出,5-[(3,5-二溴-2-吡啶)偶氮]-2,4-二氨基甲苯(简称3,5-Br_2-PADAT)是此类试剂中最灵敏、很有价值的试剂。本文参照文献合成了该试剂、并用于测定矿石中微量钻,手续简便、结果满意。试验表明,该试剂确属同类试剂中较好的。络合物的表观摩尔吸光系数达1.16×10~5;更可贵者是选择性较好,适量柠檬酸存在下,通常和钴伴生的元素几乎均能容许相当量存在。特别是铁的容许量每毫
4 - [(2-Pyridine) azo-1,3-diaminobenzene (PADAB) and its halogenated derivatives are excellent reagents for the spectrophotometric determination of trace cobalt. PADAT and its halogenated (especially dihalogenated) derivatives formed after the introduction of a methyl group on the benzene ring are more sensitive and, in particular, more selective. The literature states that 5 - [(3,5-dibromo-2-pyridyl) azo] -2,4-diaminotoluene (3,5-Br_2-PADAT) is the most sensitive and valuable of these reagents Of reagent. This reference literature synthesis of the reagent, and for the determination of micro-drilling ore, the procedure is simple, the results are satisfactory. Experiments show that the reagent is indeed a good reagent of the same kind. The apparent molar extinction coefficient of the complex is 1.16 × 10 ~ 5. More valuable is the better selectivity. In the presence of appropriate amount of citric acid, almost all elements associated with cobalt can tolerate almost the same amount. In particular, the allowable amount of iron per milliliter