Determination of Melamine of Milk Based on Two-dimensional Correlation Infrared Spectroscopy

The adulteration of milk with harmful substances is a threat to public health and beyond question a serious crime. In order to develop a rapid, cost-effective, high-throughput analysis method for detecting of adulterants in milk, the discriminative analysis of melamine is established in milk based on the two-dimensional (2D) correlation infrared spectroscopy in present paper. Pure milk samples and adulterated milk samples with different content of melamine were prepared. Then the Fourier Transform Infrared spectra of all samples were measured at room temperature. The characteristics of pure milk and adulterated milk were studied by one-dimensional spectra. The 2D NIR and 2D IR correlation spectroscopy were calculated under the perturbation of adulteration concentration. In the range from 1400 to 1800 cm(-1), two strong autopeaks were aroused by melamine in milk at 1464 cm-1 and 1560 cm(-1) in synchronous spectrum. At the same time, the 1560 cm(-1) band does not share cross peak with the 1464 cm(-1) band, which further confirm that the two bands have the same origin. Also in the range from 4200 to 4800 cm(-1), the autopeak was shown at 4648 cm(-1) in synchronous spectrum of melamine in milk. 2D NIR-IR hetero-spectral correlation analysis confirmed that the bands at 1464, 1560 and 4648 cm(-1) had the same origin. The results demonstrated that the adulterant can be discriminated correctly by 2D correlation infrared spectroscopy.