TITLE:
Oxidation and Complexation-Based Spectrophotometric Methods for Sensitive Determination of Tartrazine E102 in Some Commercial Food Samples
AUTHORS:
Magda M. S. Saleh, Elham Y. Hashem, Najat O. A. Al- Salahi
KEYWORDS:
Tartrazine E102, Food Colorants, Complexation, KMnO4, Spectrophotometric Analysis
JOURNAL NAME:
Computational Chemistry,
Vol.4 No.2,
April
28,
2016
ABSTRACT: Two new sensitive spectrophotometric methods are reported for determination of tartrazine (Tz)
(E102) in some commercial food samples. The first method involves two coupled reactions, the
reduction of Cu(II) to Cu(I) by the analyte in acetate buffer medium (pH = 5.9) at 30°C and the
complexation reaction between Cu(I) and Tz oxidized form to yield Cu-Tz complex (method I). The
other method is based on oxidation of Tz by alkaline KMnO4. These reactions are monitored spectrophotometrically
at maximum absorbances 332 and 610 nm for methods (I and II) respectively.
Variables affecting these reactions are carefully studied and the conditions are optimized. The
stability constants are calculated at 293, 303, 313 and 323 K. The thermodynamic parameters,
Gibb’s free energy change (ΔG), entropy change (ΔS), and enthalpy change (ΔH) associated with
the complexation reaction are calculated and discussed. Under optimized conditions the proposed
methods (I, II) obey Beer’s law 10.69 - 85.50, 5.34 - 34.12 μg·ml-1 of Tz respectively. The molar
absorptivity, sandel sensitivity, detection and quantification limits are calculated. Matrix effects
are also investigated. The methods are successfully applied to the quantification of Tz in different
commercially food samples. The results obtained are in good agreement with those obtained by
the reported methods at the 95% confidence level.