Derivatives add some noise to the spectra, as they increase the level (first, second, third, fourth,..), we can use this as an advantage to check for noise in the raw spectra due to scans in not stable instruments, poor sample presentation, spectra with high absorbance values, and other sources of noise.
In the video we can see the fourth derivative applied to raw spectra and how some have of them have extreme noise. Scale of the Absorbance axis is disturbed because of these extreme noisy spectra that we have to remove from the database.
