Determination of Melamine in Dry Milk by New Infrared Spectroscopy Method

The present work describes a new infrared spectroscopy method for the quantitative determination of melamine in dry milk. The applied technique is Fourier transform Infra-Red method. In this technique, standard melamine was prepared by using the potassium bromide tablet. The absorbance corresponding to the concentration was obtained at a resolution of 1-4 cm in the range of 400-4000 cm-1 and the resulted spectrum was compared with the standard milk spectrum. The equation was calculated at a peak specific for melamine and twelve local milk samples were analyzed for the determination of melamine. The precision of the Method was also verified using the repeatability during one day (intra-day) and three days (inter-day), which was RSD% on the same day did not exceed 1.85%, while during three consecutive days did not exceed 0.33%. The limit of detection and the limit of quantification of the method were (90 ppm) and (900 ppm), respectively. The method was successfully applied to infant powder milk samples and gave good recoveries (99.5–100.6%). The developed method is simple, cost-effective, rapid and does not require any separation steps. The developed method was successfully applied to the infant formula and all dry milk samples in the local market.