双波长双指示剂催化动力学光度法测定痕量铁

来源期刊：冶金分析2010年第5期

论文作者：柴红梅 高楼军 杨少卫

文章页码：58 - 60

关键词：铁； 双波长； 双指示剂； 催化光度法； 中性红； 亚甲基蓝

Key words：iron； dual-wavelength； dual-indicator； catalytic spectrophotometry； neutral red； methylene blue

摘    要：研究了在盐酸介质中,痕量铁(Ⅲ)催化H2O2氧化中性红和亚甲基蓝褪色的指示反应。通过测量520 nm和660 nm处催化和非催化体系吸光度的变化,利用铁(Ⅲ)的浓度与两波长处吸光度差值的和呈线性关系,建立了双波长双指示剂催化动力学光度法测定痕量铁的新方法。方法的线性范围为0.004～0.02μg/mL,检出限为8.5×10^-5 μg/mL,除等量的铜有干扰外,常见离子和Ce(Ⅳ)、La(Ⅲ)允许量都较大,用于环境水样中痕量铁的测定,不需要预分离。本法已用于雨水、管网水、山泉水、河水中痕量铁的测定,相对标准偏差在1.9%～3.5%之间(n=6),加标回收率为97%～105%。

Abstract: An indicating reaction,in which trace ion(III) catalyzed the fading of oxidization of methylene blue and neutral red by hydrogen peroxide in HCl medium was studied,and a new dual-wavelength and dual-indicator catalytic kinetic spectrophotometric method was established for the determination of trace iron.The Absorbence of catalytic and non-catalytic systems was measured at 520 nm and 660 nm respectively.The concentration of iron(III) showed linear relationship with the difference between Absorbence at two wavelengths.The linear range of method was 0.004-0.02 μg/mL and the detection limit was 8.5 ×10^-5 μg/mL.A large number of common ions,Ce and La(III) except for equal amount of Cu²⁺ did not interfere in the determination of iron(III).The method could be applied to the determination of trace iron(III) in environmental water samples(such as rain water,tap water,spring water and river water) without pre-separation,giving the relative standard deviations (RSDs) of 1.9%-3.5%(n=6) and the recoveries of 97%-105%.