Low concentration melamine detection with surface enhanced Raman spectroscopy

Abstract

Melamine is rich in nitrogen and easily confound with natural protein present in dairy products. It is added to diluted milk to increase the protein concentration. However, interaction of melamine and cyanuric acid in our bladder triggers the formation of kidney stones, which results in acute kidney failure. The significance of this is accentuated in the case of infant formula, which is the sole source of food for infants, with several feedings a day. Raman spectroscopy is a photonic method capable of identifying unknown molecule through a biochemical fingerprint, from its scattering spectrum. It is simple, rapid, portable and pre-treatment is unnecessary. Our work here explores low concentration of melamine detection using Raman spectroscopy with gold coated slide (GS) as substrate. By observing melamine characteristic peak at 676cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , the intensity of the peak is observed at different concentration. The peak is occasionally visible up to 0.5ppm with very low intensity. Data pre-processing which include background subtraction and baseline removal is done to improve the spectra quality. It can be concluded that Raman spectroscopy with GS substrate is capable to detect melamine at low concentration. However, an optimization of pre-processing technique is essential to improve the detection limit to lower concentration.