Fabrication of SERS substrate for the detection of rhodamine 6G, glyphosate, melamine and salicylic acid

We report on the development of a highly sensitive and novel surface enhanced Raman scattering (SERS) substrate for the detection of analytes, such as rhodamine 6G (R6G), glyphosate, melamine and salicylic acid. The fabrication steps include (a) cleaning the surface of the Cu-grids on carbon support layer with an initial glow discharge treatment, (b) layering of carbon film with a thickness of 3 nm, (c) application of 24 μl volumes of silver colloid to form silver dendrites, and (d) a glow discharge treatment of silver dendrites to remove surface debris or particles. The substrate demonstrated excellent SERS measurement reproducibility, along with a significant SERS enhancement factor of 6.1 × 105 of Raman signals and highly informative chemical signature of R6G. The SERS substrate can be used as a quantitative tool. The protocols for fabrication of the substrate are inexpensive and it is more sensitive than conventional Raman technique and a commercial product. Highly sensitive detection limits for R6G (240 ppb), glyphosate (845 ppb), melamine (630 ppb) and salicylic acid (600 ppb) were achieved with this substrate. This study has shown that the Ag-Cu-grid substrate is well suited for routine environmental monitoring of chemical residues and the detection of plant metabolites. The stability of the nano-structured Ag-Cu-grid was demonstrated during a 4 week storage period.