simultaneous kinetic determination of Fe(II) and Fe(III) by spectrophotometric H- point standar addition method

Abstract

In 1988, Bosch-Reig and Compais-Falco [1] presented a new technique H-point standard <br><br>addition method (HPSAM), that was based on the principle of dual wavelength <br><br>spectrophotometer and the standard addition method. The greatest advantage of HPSAM is <br><br>that it can remove the errors resulting from the presence of an interfering and blank reagent. <br><br>So, HPSAM can determine the two components simultaneously [2-4]. <br><br> In this work, a kinetic model has been constructed to investigate the possibility of the <br><br>simultaneous of Fe (II) and Fe (III) or selective determination of Fe (III) in the presence of <br><br>Fe (II) by using HPSAM. <br><br> The method was based on the difference in the rate of two processes ; reduction of <br><br>Fe(II) whit cystein and subsequent complex formation whit 1,10-phenanthrolin ,and direct <br><br>complex formation between Fe(II) and 1 ,10-phenanthrolin. <br><br> The optimum conditions, for Simultaneous Kinetic-determination of Fe (II) and Fe (III), <br><br>Such as 1, 10-phenanthrolin concentration, cystein concentration, pH, temperature, and <br><br>ionic strength were investigated. <br><br> The calibration curve was linear in the range of 0.2 µg/ml to 4 µg/ml for Fe (II) and Fe <br><br>(III), both. Relative standard deviation for five replicate analysis of 1 µg/ml Fe (II) and 1 <br><br>µg/ml Fe (III) were obtained 3% and 2%, respectively. The effects of interferences also were <br><br>investigated. The proposed method was successfully applied for the determination of Fe (II) <br><br>and Fe (III) in the drinking water.