الفهرس 
MelamineOnly 14 pages are availabe for public view
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Abstract
Melamine and its metabolite cyanuric acid have several ways to contaminate milk and milk-based products. They can be intentionally added to illegally increase protein content of milk-based products in protein tests or they can cross contaminate food from package materials.
Unfortunately, the residues of the two compounds cannot be determined easily in milk-based products due to the interference of high protein content. Therefore, there is a need for the rapid and accurate method of analysis for each of melamine and cyanuric acid residues in milk-based products to detect such compounds in handled foods in local markets.
Considering the previous background, the present work aimed to:
4- Optimization of analytical method for determination of Melamine and cyanuric acid in liquid milk and baby milk products LC-MS/MS.
5- Validation of the analytical method for determination of Melamine and cyanuric acid in liquid milk and baby milk products.
6- Monitoring the Melamine and cyanuric acid in some food products in Egyptian local markets.The obtained results could be summarized as follows:
I. Developing and validating a reliable LC-MS/MS MRM method for melamine and cyanuric acid analysis:
1) The proper HPLC column for melamine and cyanuric analysis was HILIC column with HPLC method as follows:
A flow rate (500 μl/min), time at 0 and 4 minute with 100% eluent (A) 90/5/5Acetonitrile/Isopropanol, /10 mM ammonium acetate in water + 0.1 % Formic acid, then washing 4 minutes by eluent (B) DIW, and equilibration with first condition for another 8 minutes.
2) Developing a reliable LC-MS/MS MRM method for melamine and cyanuric acid analysis indicated that the most sensitive transitions of melamine were selecting the mass of parent ion was 127 dalton, selecting the mass of daughter ions was 85 and 68 dalton, collision energy (27,43), declustering potential (66 and 61), exit potential (14 ,2) and entrance potential (10).
3) The mass parameters of final developed MRM method for cyanuric acid analysis were: selecting the mass of parent ions was 128 dalton, selecting the mass of daughter ions was 85 and 42 dalton, collision energy (-14,-26),declustering potential (-45 and -50), exit potential (-5) and entrance potential (-10).
4) Developing of extraction method for melamine and cyanuric analysis in milk-based products resulted in choosing 100 mM ammonium acetate buffer at pH 4 for denaturation of protein and extraction of target compounds based on the resulted accepted recovery and precision of fortified and real samples.
5) Recovery for analysis of melamine using the developed method indicated average rate of recoveries ranged from 78% to 94% for liquid milk with RSD ranged from 2.8 to 4.5%, and for baby milk sample ranged from 74 to 89% with RSD ranged between 1.6 and 2.9%
6) Recovery for analysis of cyanuric acid using the developed method indicated average rate of recoveries ranged from 83% to 99% for liquid milk with RSD ranged from 4.4 8.6%, and for baby milk sample ranged from 84 to112% with RSD ranged between 2.8 and 8.3%
7) The LOD melamine determination in using the presented method was 0.003 and 0.02 mg/kg, for liquid milk and baby milk samples, respectively. The LOD cyanuric acid was 0.03 and 0. 2 mg II. Proficiency tests
As external verification for the method, a three Proficiency test samples for melamine and two for cyanuric were tested using the presented method and acceptable results were obtained for both compounds in all rounds.
III. Monitoring melamine and cyanuric acid in different samples and different commodities collected from local markets.
Analysis of melamine and cyanuric acid in different samples and different commodities collected from local markets in Egypt showed that baby milk samples are free melamine and cyanuric acid while melamine was detected in three food supplement and soya protein samples by a concentration not exceed the MRL of melamine.