Screening liquid milk for adulterants using the B&W Tek i-Raman Plus portable Raman spectrometer

The B&W Tek i-Raman Plus portable Raman spectrometer can be used for screening liquid milk for reagent-less screening of milk for adulterants at the point of collection.

The 2008 adulteration of milk powder and infant formula with melamine that sickened more than 300,000 people and resulted in the deaths of three infants prompted several Fourier transform-Raman and Raman spectroscopic studies to detect melamine and other N-rich compounds such as dicyandiamide (DCD), urea and ammonium sulfate in milk powder.

The portable Raman mini-spectrometer used in this study was a B&WTek i-Raman Plus portable Raman spectrometer with a spectral resolution of 4 cm⁻¹, a 785 nm solid state excitation laser (300 mW) and a focusing fibre-optic probe.

Raman spectroscopy provides a wealth of information as a molecular vibrational analytical tool because of the rich complexity inherent in its signals. It provides a unique fingerprint of a molecule that is sensitive to both its molecular structure and composition and thus enables identification of different polymorphs and phases of the same compound in different environments. Two particular advantages of Raman over the complementary technique of infrared spectroscopy are very low water signal and generally discrete bands, which improve the sensitivity for analysis of aqueous solutions (eg, biological fluids and milk) compared with infrared techniques.