Spectral profile of H₂CO, CS, and CN for the full sample analyzed in this work. The profile is obtained over the disk region determined by the parameters of Table 3 (continuous lines) and in the inner region with dimmed flux (dashed lines). The vertical line indicates the systemic velocity constrained from the moment 0 map. The two arrows denote the wavelength of the CN blended lines (see Table 2). Both the horizontal and vertical scales of the various diagrams are different.