Noise spectra acquired with the Metrohm NIRS DS2500 and an FT-NIR instrument in reflection mode using a reference material with an absorbance between 0.25 and 0.4. On the FT system, the scanning speed was adjusted to match the same data acquisition time of the Metrohm NIRS DS2500 (~ 20 s) with FT data acquisition parameters: double-sided bi-directional interferogram; phase resolution twice as high as set spectral resolution; scanning speed: 5 kHz to 10 kHz; Blackman-Harris 3-term apodization window; Mertz phase correction