Qualitative and Quantitative Determination of Melamine by Surface-Enhanced Raman Spectroscopy Using Silver Nanorod Array Substrates

Silver nanorod (AgNR) array substrates are investigated to detect pure melamine dissolved in 50% methanol using surface-enhanced Raman spectroscopy (SERS). We find that sample preparation conditions have a great influence on melamine detection. When the samples are prepared under a nitrogen glove box, the SERS characteristic peak intensities of melamine at Deltanu = 497 cm(-1), 704 cm(-1), and 983 cm(-1) are studied as functions of melamine concentration and/or the mass of melamine. The peak intensities increase almost linearly when the melamine concentration increases from 0.1 mg/L to 10 mg/L and saturate when melamine concentration is greater than 50 mg/L. The bulk melamine limit of detection (LOD) is 0.1 mg/L, which is one order of magnitude less than the current standard. This study shows that AgNR based SERS detection can be used as a fast, highly sensitive, and quantitative detection method for melamine.