The spectroscopic properties of a sample of nine Seyfert 1, six NLS1, 26 Seyfert 2, and three starburst galaxies have been studied at mid-infrared wavelengths in order to determine if the frequency of detection of the brightest emission lines and the continuum shape are correlated with the degree of activity. The raw data were obtained from the Spitzer Infrared Spectrograph (IRS) archive and reduced with the pipeline (version 17.2). The spectra of the galaxies were grouped by type of activity. We conclude through this study that in general the continuum shape of the active galactic nuclei (AGN) is flat between 5 μm and 12 μm, and strong variations are found at longer wavelengths in this sample.
