Determination of melamine and malachite green by surface-enhanced Raman scattering spectroscopy using starch-coated silver nanoparticles as substrates

Abstract

Silver nanoparticles (AgNPs) were synthesized by a classic method. The surface-enhanced Raman scattering (SERS) activity of the as-synthesized substrates was evaluated by measuring the SERS signals of several different target analytes. The influence of starch concentration on AgNPs was studied and 1.00% (w/v) of starch was selected. The starch-coated AgNPs displayed a higher stability than the classic AgNPs. The practical application of the starch-coated SERS substrate was evaluated by determination of melamine and malachite green. Under the optimal conditions, melamine and malachite green were determined in the ranges of 2.00–50.0 μg L⁻¹ and 0.500–35.0 μg L⁻¹ with correlation coefficients of 0.9992 and 0.9979, and the detection limits were 0.600 μg L⁻¹ and 0.080 μg L⁻¹, respectively. The recoveries of melamine in spiked milk samples and malachite green in water samples were 94–104% and 96–107%, respectively. These results foresee promising application of starch-coated AgNPs as sensitive SERS substrates in both food and environmental water.