Colorimetric Determination of Trace Iron in Water Samples by Using a Poly(Vinyl Chloride) Membrane Containing Bathophenanthroline as a Solid-Phase Extraction Medium

Abstract

Trace iron was determined by solid-phase extraction using a polymer membrane as an extracting medium. The polymer membrane consisted of 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline) as a chelating agent, o-nitrophenyl octyl ether (o-NPOE) as the extracting solvent, and polyvinyl chloride) (PVC). When the PVC membrane came into contact with iron in the samples, the membrane changed from colorless to red, and the color intensity was proportional to the iron concentration. The iron concentration was calculated from a calibration graph, after the absorbance of the colored membrane was measured spectrophotometrically. With this method, iron concentrations ranging from 2.76 × 10⁻⁷ to 4.29 × 10⁻⁵M were determined quickly and easily.