Figure 2: The typical Mass spectra of (a) amantadine, 2380.0 ng mL-1 (b) memantine, 2380.0 ng mL-1 (c) amantadine (119.0 ng mL-1, analyte) and memantine (2380.0 ng mL-1, internal standard) in 50% aqueous solution of acetonitrile containing 0.1% formic acid.