Abstract

DETERMINATION OF MELAMINE IN INFANT FORMULA BY SPECTROPHOTOMETRY

Razan Awad Gadelrab Ahmed, Abdalla A. Elbashir* and Mohamed Mustafa Ibrahim

ABSTRACT

A new and simple spectrophotometric method has been developed and validated for measuring the melamine residue in infant milk formula. The method is based on measuring the absorption of an orange complex formed from melamine and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) at alkaline medium (pH 12.0) which exhibit maximum absorbance at 465 nm. Different variables affecting the reaction of melamine with NBD-Cl such as pH, temperature, reaction time and NBD-Cl concentration have been studied and optimized. Under the optimized reaction conditions, Beer’s law is obeyed over the range of 1.0 - 8.0 μg/mL with a linear correlation coefficient (r2=0.999). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.14 and 0.44 μg/mL respectively. The relative standard deviation (RSD) did not exceed 3.1 %, indicating that the proposed method has good repeatability and reproducibility. The method is useful for routine analysis of melamine in quality control laboratories.

Keywords: Spectrophotometric, Melamine, 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole and infant milk formula.