Spectrophotometric determination of iron (III)with 4-(2-pyridiazo)-resorcin

Abstract

4-(2-Pyridylazo)-resorcin (PAR) reacts sensitively with iron (III) to form a water-soluble red complex in the presence of nitrilo-triacetic acid (NTA). The complex gives a fixed value of absorbance at pH 8.0 to 9.3, and its maximum absorbance lies at 536 mμ. The sensitivity is extremely high, since its molar extinction coefficient 6.04×104 is 6 and 3 times as much as those of 1, 10-phenanthrolin complex and bathophenanthrolin complex, respectively. While many ions interfere, more than 10 metal ions are masked by the presence of NTA and an addition of CyDTA. Cobalt and nickel are masked by potassium cyanide. Cu, Ga, Ti, Hf, Cr, U, V, Sn, Ta, Au, Bi, and Zr interfere. The method is useful for the determination of ppb iron (III) in water. © 1965, The Japanese Society of Physical Fitness and Sports Medicine. All rights reserved.