Sensitive Detection of Melamine in Infant Milk and Coffee Mate by a Buffer Mediated Extraction and HPLC-PDA Analytical Method

Melamine is a potentially hazardous compound and one of the major concerns especially in dairy products and pet foods. In the present study a sensitive, simple and reliable method for extraction and determination of melamine in infant milk and coffee mate has been developed. This method consists of an initial extraction in buffer media prepared by formic acid and sodium formate, followed by protein precipitation by acetonitrile and dichloromethane. The chromatographic separation was carried out on a 100-Nucleosil -NH2 column with an optimized acetonitrile-water (80:20 v/v) as a mobile phase and with a photodiode-array detector. The analytical method was validated according to the validation parameters, such as, selectivity, linearity (0.08-10 µg/mL, with r2= 0.9998 and 0.05-10 µg/mL with r2= 0.9997), precision (intra-day 0.52-2.66%, 0.78-1.20; inter-day 2.96-4.20%, 2.80-3.00%) and accuracy (92-102%, 92-100%) for powdered milk and coffee mates respectively. The limits of detection and quantization were 0.02, 0.08 µg/mL for powdered milk and 0.01, 0.05 µg/mL for coffee mate, respectively.