Spectral subtraction and baseline correction via interactive graphics programs have been extensively used for the analysis of weak IR absorption signals which are under strong bands, such as occur in aqueous protein solutions. However, personal bias and uncertainty can result in significant differences in the spectra of the same protein substracted and baseline corrected by different persons. This is demonstrated in the case of albumin adsorbed on the surface of a germanium ATR crystal in contact within pure water. A simple computer algorithm to automatically subtract the water spectrum and remove any baseline tilt or curvature, and thus remove this individual bias and uncertainty, is presented, with a comparison of the results between different persons and the algorithm.
J. R. Powell, F. M. Wasacz, and R. J. Jakobsen, "An Algorithm for the Reproducible Spectral Subtraction of Water from the FT-IR Spectra of Proteins in Dilute Solutions and Adsorbed Monolayers," Appl. Spectrosc. 40, 339-344 (1986)