新显色剂二溴氟基偶氮甲胂分光光度法测定热镀锌中痕量镧

Spectrophotometric determination of tracea mounts of lanthanum in zinc alloy with new chromogenic reagent 5-MasA-DBF

报道了新显色剂3-[（2-胂羧基-5-甲基苯）偶氮]-6-[（2，6-二溴-4-氟苯）偶氮]-4，5-二羟基-2，7-萘二磺酸（简称5．MasA．DBF）测定锌合金中痕量镧的分光光度法。在0．1mol／L盐酸介质中，镧与新显色剂5-MasA-DBF形成了配合比为1：2蓝紫色配合物，其最大吸收波长为640nm，表观摩尔吸光系数ε=1．30×10^6L·mol^-1·cm^-1，线性范围为0～24μg／25mL，加标回收率为94．3％．100．8％。该法用于锌合金中微量镧的测定，方法的相对标准偏差〈5．45％，结果满意。

In acidic solution of 0.01 mol·L^- 1 hydrochloric acid, new chromogenic reagent 5-MasA-DBF reacts with lanthanum （ Ⅲ ） to form a bluish violent coordination complex. Its maximum absorption was at 640 nm. The apparent molar absorptivity of this coordination complex was found to be 1.30×10^6L·mol^-1·cm^-1 .Beer＇s law held in the range of 0- 24μg of La（ Ⅲ ） per 25 mL of solution. Based on the results of interference tests, the color reaction was applied to the determination of lanthanum in zinc alloys successfully.