Food Analytical Methods

, Volume 2, Issue 3, pp 221–225

Spectrophotometric Trace Determination of Iron in Food, Milk, and Tea Samples using a New Bis-azo Dye as Analytical Reagent


DOI: 10.1007/s12161-008-9054-z

Cite this article as:
Sharma, A.K. & Singh, I. Food Anal. Methods (2009) 2: 221. doi:10.1007/s12161-008-9054-z


A newly synthesized bis-azo dye, 2,6-bis(1-hydroxy-2-naphthylazo)pyridine (PBN) was used as a sensitive reagent for iron. To determine the metal ion using a spectrophotometer in the concentration range between 0.3 and 2.76 ppm (molar absorptivity of 2.65 × 104 l mol−1 cm−1 at 550 nm). In a phosphate-buffered medium, none of the transition metals, except Fe(II), Co(II), Ni(II), Cu(II), and Hg(II), produced color with the reagent; however, colors produced by Co(II), Ni(II), Cu(II), and Hg(II) could be masked using thiosemicarbazide, therefore, making the reagent highly selective for iron determination. The reagent was applied for the estimation of iron levels in milk, food grains, and tea samples and the results were compared with the iron levels found in those samples using AAS.


ChromogenicIron DeterminationSpectrophotometry2,6-bis(1-hydroxy-2-naphthylazo)pyridine (PBN)

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Department of ChemistryG. J. University of Science & TechnologyHisarIndia
  2. 2.Department of ChemistryM. D. UniversityRohtakIndia