(A) The SERS electropherogram of the six aliphatic side chain amino acids indicates that Leu migrates at tm = 163 ± 8 s, Ile at tm = 206 ± 5 s, Val at tm = 320 ± 11 s, Pro at tm = 332 ± 7 s, Ala at tm = 360 ± 10 s, and Gly at tm = 360 ± 14 s. The signal threshold (>4σ) was set to 230. (B) Averaged SERS spectra of (i) Leu, (ii) Ile, (iii) Val, (iv) Pro, (v) Ala, and (iv) Gly extracted from the electropherogram in (A) between 162.9 and 163.6 s, 205.7 and 206.6 s, 316.5 and 317.2 s, 332.5 and 333.1 s, 356.2 and 357.0 s, and 358.7 and 359.5 s, respectively. The amino acid concentration in this mixture is 16×10−5 M.