Column density ratio of C₂H₅CN to CH₃CN versus bolometric luminosity for low- and high-mass sources. The red points show the values for ALMAGAL sources from this work. Blue and pink show values for low- and high-mass protostars taken from the literature (see Table E.4 for the references). Moreover, the purple bar shows the range of C₂H₅CN/CH₃CN peak gas-phase values from Garrod et al. (2022) in the warm-up stages with slow, medium and fast pace (from their Table 17, final model setup). The purple arrow shows that the range of models are higher than the range in this plot. Upward triangles show lower limits and downward triangles show upper limits. Grey solid line and shaded gray area show the mean and standard deviation weighted by the uncertainty on the log₁₀ of each column density ratio after eliminating upper and lower limits. Moreover, Sgr B2(N2) is eliminated in the derivation of mean and standard deviation, as it often seems to be an outlier.