在溴化十六烷基三甲铵存在下二苯偶氮羰酰肼与钒(Ⅴ)的显色反应研究及应用

Study on the Colour Reaction of Vanadium(Ⅴ) with Diphenylcarbazone and Cetyltrimethylammonium Bromide and Its Analytical Application

研究了在溴化十六烷基三甲铵（ＣＴＭＡＢ）存在下，钒（Ⅴ）与二苯偶氮羧酰肼（ＤＰＣＯ）显色反应的分析特性，利用此反应建立了测定微量钒的新方法。在ｐＨ４～６的乙酸－乙酸钠缓冲介质中，钒（Ⅴ）与二苯偶氮羰酰肼和溴化十六烷基三甲铵反应生成一红色配合物，配合物的最大吸收波长位于５４０ｎｍ。表观摩尔吸光系数为５．６×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，钒量在０～２５μｇ／２５ｍＬ范围内符合比尔定律。用摩尔比法和等摩尔连续变化法测得配合物组成比为Ｖ（Ⅴ）∶ＤＰＣＯ∶ＣＴＭＡＢ＝１∶２∶２。该方法操作简便，有较高的灵敏度和较好的选择性，已用于钢铁和岩矿试样中微量钒的测定，结果满意。

A new sensitive spectrophotometric method for the determination of trace vanadium has been developed,based on the reaction of vanadium(Ⅴ) with diphenylcarbazone (DPCO) and cetyltrimethylammonium bromide(CTMAB) to form a red complex in HAc NaAc solution at pH4～6.The complex shows maximum absorption at 540nm with an apparent molar absorptivity of 5.6×10 4L·mol -1 ·cm -1 .The composition of the complex is V(Ⅴ)∶DPCO∶CTMAB=1∶2∶2,Beer's law is obeyed in the range of 0～25μg/25mL for vanadium.The method is highly sensitive and selective,and has been applied to the determination of trace vanadium in steel and minerals with satisfactory results.