Determination of trace iron by kinetic polarography based on inhibitory fading of ethyl orange oxidized by potassium bromate
阻抑溴酸钾氧化乙基橙褪色动力学极谱法测定痕量铁

In dilute sulfuric acid medium,trace Fe(Ⅲ) had strong inhibitory effect on the fading reaction of ethyl orange oxidized by potassium bromate.The ethyl orange showed a sensitive polarographic adsorptive wave at-0.60 V on electrode in ammonia medium.Based on this,the change of ethyl orange concentration in inhibitory reaction was monitored by polarography.Consequently,a new determination method of trace Fe(Ⅲ) by inhibitory kinetics polarography in Fe(Ⅲ)-potassium bromate-ethyl orange system was established.The effect of sulfuric acid dosage,potassium bromate dosage,ethyl orange dosage,reaction temperature and time on the determination of Fe(Ⅲ) was investigated.Under the optimal conditions,the linear range of method was 0.004 8-0.4 μg/mL.The detection limit was 0.002 1 μg/mL.The proposed method was applied to the determination of iron in water.The results were consistent with those obtained by flame atomic absorption spectrometry.The relative standard deviation(RSD) was 1.2 %-2.9 %.