新星色剂2－（2＇，4＇，6＇－三羟苯基偶氮）苯胂酸的合成与性质

Synthesis and analytical behaviors of a new reagent 2- (2', 4', 6' -trihydroxyphenylazo) benzenearsonic acid

报道了新显色剂２（２＇，４＇，６＇－三羟苯基偶氮）苯肿酸（ＴＰＢＡ）的合成、纯化和结构鉴定。研究了该试剂与３０余种金属离子的显色反应，发现在弱酸性（ＰＨ＜７．０）介质中，试剂仅与Ｆｅ（Ⅲ）发生专一反应，故有可能拟订出弱酸性介质中测定Ｆｅ（Ⅲ）的高选择性光度法。

This paper reports the synthesis, purification and structure identification of a new reagent, 2-(2', 4',6'-trihydroxyphenylazo) benzenearsonic acid (abbreviated as TPBA). The analytical behaviors of TPBA including acidic dissociation constants and color reaction with more than 30 metal ions have been inves tigated. The results show that in weakly acidic media (pH 7.0), TPBA reacts only with iron(Ⅲ). Thus a highly selective method for the spectrophotometricdetermination of iron (Ⅲ) may be established (analy tical applications will be reported in a separate paper).