Optimization of extraction conditions and determination of melamine in egg using high-performance liquid chromatography

The presence of melamine in foods is one of the important issues in terms of food safety and consumer health. Extraction is the first step in determining the amount of melamine in foods. Therefore, in the current study, melamine extraction from egg was optimized using response surface methodology based on the central composite design. The percentage of water used in the extraction phase containing water/acetonitrile, extraction phase volume, extraction time, pH of extraction phase, and hydrochloric acid concentration in the extraction phase were considered as the studied variables for optimizing extraction conditions. Finally, the amount of melamine present in four brands of egg was measured by high-performance liquid chromatography (HPLC) using internal standard method. Optimum extraction conditions were obtained in the form of 39.28% water in the extraction phase, 5.06 mL extraction solvent volume, 12.48 min extraction time, pH 5.04 and acid concentration of 0.73 M. The amount of melamine in the egg samples was in the range of 0.19-0.45 mg/kg. Regarding the amount of melamine authorized by the EU and the US Food and Drug Administration, it can be concluded that the melamine content of the samples is within the limits of the EU standard and only in two samples was more of the USFDA standard.