DETERMINATION OF IRON(II) IN WATER BY A SPECTROPHOTOMETRIC METHOD AFTER PRECONCENTRATION ON AN ORGANIC SOLVENT-SOLUBLE MEMBRANE-FILTER

A solvent-soluble membrane filter is proposed for a simple and rapid p reconcentration and spectrophotometric determination of iron (II), whi ch was collected on a nitrocellulose membrane filter as an ion-associa te of the cationic complex of iron (II)-1,10-phenanthroline with an an ionic surfactant of dodecyl sulfate. The ion-associate collected was d issolved in 5 ml of 2-methoxyethanol together with the filter. The col or intensity due to the ion-associate in the resulting solution was me asured at 510 nm against a reagent blank. Beer's law is obeyed in the range 1-15 mu g Fe (II) in 5 ml of solvent with excellent reproducibil ity, and detection limits better than 0.5 mu g dm(-3) as Fe (II) can b e achieved. The diverse components normally present in water do not in terfere when proper masking reagent is added. The proposed method has been applied to the analysis of water samples from several sources suc h as river water, ground water and tapwater samples, the recoveries of the iron (II) added to the samples are quantitative, and results foun d are satisfactory.