An alternative for the calculation of derivative spectra in the near-infrared spectroscopy

Savitzky-Golay differentiation procedure is a commonly used pre-processing technique in the near-infrared spectroscopy, being implemented in the instrumental or specialized data processing software. However, the spectra can be recorded linearly to the wavelength or energy scale depending on the available instrument, which leads to different derivative curves obtained by the Savitzky-Golay approach. The derivatives of the spectra linear to the wavelength scale tend to attenuate. A modified procedure, which avoids this problem, is described and the aim of this note is to bring this pre-processing alternative to the attention of the near-infrared specialists.