Quantitative comparison of five SERS substrates: Sensitivity and limit of detection

Five surface-enhanced Raman scattering (SERS) substrates were quantitatively compared for ease of preparation, sensitivity, limit of detection (LOD), reproducibility, and stability. Specifically, vapor-deposited Ag films, electrochemically roughened Ag electrodes, nitric acid-etched Ag foil, Tollens-produced Ag films, and photoreduced Ag films on TiO2 were examined. Of these substrates, post-deposition-annealed Ag films exhibited the greatest sensitivity and lowest LOD, with 152 +/- 1 counts per femtomole and an LOD of 0.36 +/- 0.02 femtomoles of trans-1,2-bis(4-pyridyl)ethene (BPE). The substrate demonstrating the poorest sensitivity and highest LOD was Ag deposited from the Tollens reaction, with 0.38 +/- 0.01 counts per femtomole and an LOD of 270 +/- 20 femtomoles of BPE. The easiest substrate to prepare, nitric acid-etched Ag foils, exhibited a sensitivity of 0.485 +/- 0.008 counts per femtomole and an LOD of 200 +/- 10 femtomoles of BPE.