IN-SITU PRECONCENTRATION METHOD FOR IRON(II) IN ENVIRONMENTAL WATER SAMPLES USING SOLID-PHASE EXTRACTION FOLLOWED BY SPECTROPHOTOMETRIC DETERMINATION

A simple and rapid method for in situ preconcentration of iron(II) in environmental water samples has been developed, based on solid phase e xtraction using Sep-Pak C18 cartridges. Iron(II) in water samples, whi ch was taken into a graduated syringe to prevent oxidation of iron(II) by air, was converted into a colored cationic complex with ferrozine (C20H12N4O6S2Na2) at pH 4.5 immediately after sample collection. The i ron(II)-ferrozine complex was adsorbed on Sep-Pak C18 as an ion-pair w ith acetate ion. The complex was stable on Sep-Pak C18 for at least 3 weeks. The adsorbed complex was eluted with a mixture of acetone and 0 .1 M hydrochloric acid. The color intensity due to the complex was mea sured at 562 nm. The proposed method is applicable to brackish and sea waters as well as fresh water.