Figure : Sparkline-style mass spectra of fentanyl analogs with indistinguishable EI-MS measurements at a dissimilarity cut off level of 0.1 (or similarity level of 0.9). For all plots, the x-axis range is between m/z 40 and m/z 320, the y-axis is relative intensity with a range between 0 and 1, and the base peak occurs at m/z 245. Label numbers correspond with IDs in Table .