Sensing of Iron Ions by Solid Phase Spectrophotometry

A new sensitive and selective spectrophotometric method for the determination of iron using a PVC membrane containing bathophenanthroline and dioctylphethalate as the solid phase extraction medium is investigated. Fe(II) in an aqueous sample solution is trapped on the membrane with an anion species, picrate ion and forms a complex with bathophenanthroline. The absorbance of the red-orange membrane is measured at 540 nm using a spectrophotometer. The influence of type and concentration of counter ion, temperature of analyte solution, time, pH and amount of reducing agent on the absorbance is investigated. The detectable limit of iron in a sample solution is in the range of 5´10-5 - 1´10-2 M. The effect of various cationic interferences on determination of iron is also studied.