4-(2-吡啶偶氮)间苯二酚分光光度法测定微量铁

Spectrophotometric Determination of Trace Iron with 4-(2-pyridylazo)-resorcinol

本文系统地研究了4-（2-吡啶偶氮）间苯二酚（PAR）与铁（Ⅱ）的显色反应、试验表明，在pH9.0～10.3范围内Fe（Ⅱ）与PAR形成稳定的红色配合物，配合物在502nm和716nm处有2个吸收峰，其表观摩尔吸光系数分别为4.8×104L·mol-1·cm－1和2．3×104L·mol-1·cm-1，配合物组成为Fe：PAR=1：3，表观稳定常数为4．2×1015。在716nm处，铁浓度在0～1.8μg／mL范围内服从比耳定律，用本法直接测定食品中微量铁，结果令人满意。

The colour reaction of iron (Ⅱ) with 4- (2-pyridylazo)-resorcinol (PAR) has been studied.Iron (Ⅱ) reacts with PAR at pH9.0~ 10. 3 to form a stable 1: 3 chelate in aqueous solution.The apparent molar absorptivity of this chelate is 4. 8 ×104L. mol-1·cm-1 (502nm ) and 2. 3 ×104L. mol-1·cm-1(716nm). Beer's law is obeyed in the range of 0~1.8μg/mL for iron (716nm). The method has been applied to the determination of trace iron in food with satisfactory results.