Fe(II)와 3,4,5-Trihydroxybeonzoic acid의 착물형성에 대한 분광광도법적 연구

Abstract

The condition of complexation between Fe(Ⅱ) and 3,4,5-Trihydroxybenzoic acid (=Gallic acid) as a new developing agent and various effect on absorbance of the complex have been investigated by spectrophotometric method. The 2:3 Fe(Ⅱ)-Gallic acid complex was formed stably in the pH range 6.5-7.0 and the maximum absorbance band of the complex appeared at 540 nm. Under these conditions, the complex followed Lambert-Beer's low from 2.0×10^(-6)M to 2.4×10^(-4)M of Fe(Ⅱ)ion, and molar absorptivity was 3.84×10^(3) 1.mol^(-1).cm^(-1). The interfering effects of various cations and anions on the absorbance of this complex were studied. The alkali metal and alkali earth metal ions were not interfered, but Zn(Ⅱ), Mn(Ⅱ), and Cd(Ⅱ) ions were interfered in the concentration over 40 times, 16 times, and 10 times of the Fe(Ⅱ) solutions. Furthermore Ni(Ⅱ), Al(Ⅲ), Cu(Ⅱ), Co(Ⅱ), and Cr(Ⅲ) ions were interfered in the same concentration of that of the Fe(Ⅱ) solution. In the investigation of anions interfering effects, interference was not observed when SO_(4)^(-2) and Cl^(-) ions were present in the sample solution up to 1000 times of Fe(Ⅱ) concentration. And CH_(3)COO^(-), F^(-), CO_(3)^(-2), ClO_(3)^(-), S_(2)O_(3)^(-2) and NO_(3)^(-) ions were not interfered in the 200 times concentration of that of Fe(Ⅱ) solution. But SO_(3)^(-2), C_(2)O_(4)^(-2), CN^(-), CrO_(4)^(-2) and pO_(4)^(-3) ions were interfered in the same concentration of that of Fe(Ⅱ) solution.;Fe(Ⅱ)와 새로운 발색제 3, 4, 5 - trihydroxybenzoic acid ( = Gallic acid )가 착물을 형성하는 조건과 형성된 착물에 미치는 여러가지 영향을 분광광도법으로 연구하였다. Fe(Ⅱ)와 Gallic acid는 PH 6.5 ∼ 7.0정도의 영역에서 조성비가 2 : 3인 안정한 착물을 형성하였고, 그 착물의 최대흡수파장은 540㎚에서 나타났다. 이러한 조건에서 Fe(Ⅱ) 을 흡광분석하였을 때 Fe(Ⅱ)이온은 2.0×10^(-6)M에서 2.4×10^(-4)M까지 Lambert-Beer법칙에 따르며 몰흡광계수는 3.84×10^(3)ℓ·㏖^(-1)·㎝^(-1)이었다. Fe(Ⅱ)와 Gal1ic acid가 착물을 형성할때 여러가지 양이온과 음이온의 방해효과를 조사한 결과 알칼리 금속 및 알칼리 토금속슥 이온들은 아무런 방해작용이 없었으나, Zn(Ⅱ), Mn(Ⅱ), Cd(Ⅱ) 이온들은 각각 Fe(Ⅱ)농도의 40배, 16배, 10배 이상에서 방해작용이 나타났으며, Ni(Ⅱ), Al(Ⅱ), Cu(Ⅱ), Co(Ⅱ), Cr(Ⅲ)이온들은 Fe(Ⅱ)와 같은 농도로 존재할 때도 방해작용이 있었다. SO_(4)^(-2), Cl^(-) 음이온은 Fe(Ⅱ) 농도의 1000배까지 공존하여도 방해작용이 없었고, CH_(3)Coo^(-), F^(-), CO_(3)^(-2), ClO_(3)^(-), S_(2)O_(3)^(-2), NO_(3)^(-) 음이온들은 Fe(Ⅱ) 농도의 200배에서도 방해작용이 없었으나, SO_(3)^(-2), C_(2)O_(4)^(-2), CN^(-), CrO_(4)^(-2), PO_(4)^(-3) 음이온들은 Fe(Ⅱ)와 같은 농도로만 공존하여도 방해작용이 있음을 알았다.