Gold colloids were found to be more effective than silver colloids for surface-enhanced Raman scattering (SERS) using a laser excitation wavelength of 785 nm. The SERS signals are highly dependent on the morphology and size distribution of the nanoparticles or nanostructures. The aggregation characteristics of nanoparticles directly correlated with the presence of SERS â hot spotsâ for signal generation. Both nanostar and Klariteâ ¢ are capable of yielding enhancement factors up to the order of 10⁶. The filling of pyramidal holes in the Klariteâ ¢ substrate with nanostar was found to be synergistic in improving the enhancement factors of the 4-aminobiphenyl from 1.4 x 10⁶ for Klariteâ ¢ alone to 3.3 x 10⁶ when combined with nanostar. The use of gold colloid, nanostar, and Klariteâ ¢ substrate allows the detection limits of o-toluidine, 4-aminobiphenyl, and 2-naphthylamine to be achieved at the levels of 0.1-1 mg/L, which is applicable for most instances of environmental monitoring with or without analyte pre-concentration.