Figure 6.

Reduced χ² analysis using (a) ¹³C or (b) ¹³C and ¹⁵N isotropic shifts for the 24 possible acetaminophen polymorph assignments using fragment, cluster, and cluster/fragment methods. The best assignment (I, II, IIIa, IIIb) is shown in red, while the blue line indicates the assignment that swaps the two monomers in form III. Gray lines correspond to other possible assignments. The ¹³C RMS errors (in ppm) for the best assignment with each model are reported near the bottom of (a).