钛(Ⅳ)-甘露醇-邻苯三酚红-溴化十六烷基三甲基铵四元体系分光光度法测定钢中微量钛

Spectrophotometric determination of micro titanium in steels with system of Ti(Ⅳ)-mannitol-pyrogallol red-cetyltrimethyl ammonium bromate

在溴化十六烷基三甲基铵(CTMAB)存在下,Ti(Ⅳ)同甘露醇和邻苯三酚红在pH3.4时形成蓝色的四元络合物,用等摩尔连续变化法测得络合物的组成为:n(Ti(Ⅳ))∶n(甘露醇)∶n(邻苯三酚红)∶n(CTMAB)=1∶1∶2∶3,络合物的最大吸收波长为630nm;25mL溶液中,Ti(Ⅳ)在0～35μg范围内符合比尔定律,表观摩尔吸光系数为3.1×105L.mol-1.cm-1。用抗坏血酸掩蔽Fe(Ⅲ),体系不需要分离可直接用于钢中微量钛的测定,结果令人满意。

In the presence of cetyltrimethyl ammonium bromate （CTMAB）,Ti（Ⅳ）can form a blue complex with mannitol and pyrogallol red（PR）at pH 3.4. A ratio of Ti（Ⅳ） ： mannitol： PR： CTMAB is determined to be 1：1：2：3 by continous isomolar changes. The complex exhibits a maximum absorption at 630 nm,Beer＇s law is obeyed in the range of 0 - 35/Lg Ti（Ⅳ） per 25 mL solution. The apparent molar absorptivity is 3.1 × 10^5 L ·mol^-1· cm^-1. By using ascorbic acid for masking Fe（Ⅲ）, the system may be applied to the determination of titanium in steels without previous separation.