Determination of trace iron in water by ion exchange resin phase spectrophotometry

A new method for the determination of trace iron by ion exchange resin phase spectrophotometry was developed.The colored complex formed by iron and pyrocatechol violet is concentrated on the styrene anion exchange resin(201×4),whose diameter is from 0.177 to 0.250 mm,and then iron can be determined directly by making thin layer at 648 nm.Besides Bi3+,Sn4+,most other coexisting ions didn't interfere in the determination. Over allowance amount of Bi3+,Sn4+ could be masked by 2,3-two sulfhydryl propanol.Beer's law is obeyed in the range of 0.004-0.24 μg/mL for iron.The detection limit is 4.1 μg/L.The method has been successfully applied to determine iron in water with RSD of 2.0%-2.3% and recovery of 98%-99%.