Analytical Sciences

Photoacoustic Spectrometric Determination of Trace Iron(II) after Preconcentration on a Membrane Filter with a Finely Pulverized Anion-Exchange Resin

Junichi SHIDA * and Isamu MASUDA

Department of Materials Science and Engineering, Faculty of Engineering, Yamagata University, Yonezawa 992, Japan

A sensitive method based on preconcentration on a membrane filter with a finely pulverized anion-exchange resin has been developed for the determination of iron(II) in water samples by photoacoustic spectrometry. Iron(II) reacts with 2-nitroso-5-(N-propyl-N-sulfopropylamino)phenol (Nitroso-PSAP) to form a water-soluble chelate anion, which is adsorbed on the resin at pH 8.0; the resulting resin is filtered through a membrane filter (13 mm in diameter). The resin with the membrane filter is inserted into a cell, and the intensity of the photoacoustic signal of iron(II) is measured at 826 nm. The calibration graph for iron(II) was linear over the range 0.05 - 0.8 mg in 30 - 500 ml of a sample solution. The relative standard deviation for eight measurements at 0.5 mg of iron(II) was 5.4%. The detection limit was 10 ng of iron(II) in 500 ml (20 ngFe l -1 ). The interference of various ions was studied and the optimum conditions were developed for the deter-mination of iron(II) in mine-drainage and river-water samples. (Keywords: Iron(II), photoacoustic spectrometry, anion-exchange resin, 2-nitroso-5-(N-propyl-N-sulfopropylamino)phe-nol)

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