ABSTRACT
A rapid, sensitive, label-free and separation-free analytical method for determination of melamine ( MA) was developed based on surface enhanced Raman scattering ( SERS ) effect of gold nanoparticles. Through tri-sodium citrate reduction method, gold nanoparticles with average diameter of 30 nm were obtained. The melamine detection platform was constructed after self-assembling 4-mercapto phenylboronic acid (4-MPBA) on the surface of gold nanoparticles through Au S covalent bond. When MA existed in solution, 4-MPBA functionalized gold nanoparticles would aggregate because of strong hydrogen bond interaction between MA and 4-MPBA. Moreover, following increase of the concentration of MA, gold nanoparticles would aggregate more intensively and form more hot spots. As a result, Raman signal of 4-MPBA and MA was enhanced greatly. The characteristic Raman peaks of 4-MPBA and MA respectively located at 1076 cm-1 and 715 cm-1 . Hence, the qualitative and quantitative detection for MA were realized based on the ratio value of I715 cm-1 to I1076 cm-1 . The linear range of MA detection was 0 . 1 μmol/L-1. 5 μmol/L. The limit of detection (LOD) reached 0. 02 μmol/L in terms of three times signal to noise.