铁(Ⅲ)与硫氰酸盐和碱性三苯甲烷染料在水溶液中的显色反应及其应用

Color reactions of iron(Ⅲ)with thiocyanate and basic triphenylmethane dyes and their applications

在酸性溶液中,铁(Ⅲ)与较高浓度的硫氰酸盐形成 Fe(SCN)_6^(3-)配阴离子。此配阴离子在阿拉伯树胶等增溶剂存在的水溶液中能与碱性三苯甲烷染料形成离子缔合物(BTMD)_3·[Fe(SCN)_6]。不同显色体系的摩尔吸光系数是ε(1.71～5.6)×10~5L·mol^(-1)·cm^(-1)。显色反应在 H_2SO_4介质中最佳。将此法用于环境水样、茶叶和某些化学试剂中痕量铁的测定,结果令人满意。

Highly sensitive color reaction systems wereproduced,based on the reaction of the anioniccomplex[Fe(SCN)_6]^(8-)formed by Fe(Ⅲ)withSCN^- to form associate complexes[TBMD]_(?)·[Fe(SCN)_(?)]with triphenylmethane dyes such asmethyl violet,crystal violet,malachite green,brilliant green,methyl green and iodine green,in acidic solution and in the presence of arabi(?)gum.The molar absorptivities are between 1.7×10~5 and 5.6×10~5 L·mol^(-1)·cm^(-1) for all thesesystems.Crystal violet and malachite greensystems are the best,and can be applied to thespectrophotometrie determination of trace amountsof iron in some samples.These methods aresimple,rapid,and have good accuracy and repro-ducibility.