Detection of melamine in milk by surface-enhanced Raman spectroscopy coupled with magnetic and Raman-labeled nanoparticles

Yazgan N. N. , BOYACI İ. H. , TOPCU A. , Tamer U.

ANALYTICAL AND BIOANALYTICAL CHEMISTRY, cilt.403, ss.2009-2017, 2012 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 403 Konu: 7
  • Basım Tarihi: 2012
  • Doi Numarası: 10.1007/s00216-012-5971-1
  • Sayfa Sayıları: ss.2009-2017


A new method based on surface-enhanced Raman spectroscopy (SERS) has been developed for sensitive and rapid detection of melamine. Spherical magnetic-core gold-shell nanoparticles (AuNPs) and rod-shaped gold nanoparticles (nanorods) labeled with a Raman-active compound were used to form a complex with the melamine molecules. 5,5'-Dithiobis(2-nitrobenzoic acid) was used as Raman-active compound because it is readily adsorbed by a gold nanoparticle surface forming a self-assembled monolayer (SAM) and has strong Raman scattering at 1330 cm(-1), because of the symmetric NO2 stretch. The calibration curve was obtained by plotting Raman band area at 1330 cm(-1) against melamine concentration. A linear relationship was obtained with a high determination coefficient (R (2) = 0.997). The method was validated for linearity, sensitivity, precision (intra-day and inter-day repeatability), and recovery. In the model system, the limits of detection (LOD) and quantification (LOQ) were 0.38 and 1.27 mg L-1, respectively. For melamine-spiked milk samples, LOD and LOQ values were 0.39 mg L-1 and 1.30 mg L-1, respectively. Intra and inter-day precision were 3.73 and 4.94 %, respectively. This method was applied to samples of skimmed milk that had been spiked with melamine at different concentrations. The recovery of the method was 95-109 % in the concentration range 2-15 mg L-1, and average RSD was 1.71 %. Total analysis time was less than 15 min.