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3-(2-胂酸基苯偶氮-6-(2,6-二溴-4-氯苯偶氮)-4,5-二羟基-2,7-萘二磺酸(简称DBC-偶氮胂)可在高酸度下(0.2—1.7NHCl)与稀土元素发生灵敏显色反应,且选择性非常好,前文已报导用该试剂直接光度测定高温合金中微量铈。 本文研究了DBC-偶氮胂在水溶液中的离解作用,用pH电位法及分光光度法测定DBC-偶氮胂及各级条件离解常数,结果表明:由于多卤素原子的引入,使试剂更易于质子化;因而离解常数比偶氮胂Ⅲ大。
3- (2-Arsanophenylazo-6- (2,6-dibromo-4-chlorophenylazo) -4,5-dihydroxy-2,7-naphthalenedisulfonic acid (abbreviated as DBC-even Arsenazo) can react sensitively with rare earth elements under high acidity (0.2-1.7NHCl), and the selectivity is very good. It has been previously reported that this reagent can be used for the direct spectrophotometric determination of trace cerium in superalloy. In this paper, DBC-even Arsenazo dissociation in aqueous solution, the pH potential method and spectrophotometric determination of DBC-arsenazo and the dissociation constants at all levels, the results show that: due to the introduction of polyhalogen atoms make the reagent more easily protonated; thus the dissociation constant Than arsenazo Ⅲ large.