Figure 1.

Schematic overview of the method used to acquire and analyze FTIR spectra. The left-hand images illustrate the experimental setup, while the right-hand images show average spectra derived from a glass microscope slide and a membrane slide (A), sample raw spectra from 16-µm-thick tissue sections, illustrating variation in the baseline (B), modeled baseline artifacts after four rounds of baseline correction using a partial least squares regression model (C), and baseline-corrected spectra revealing the chemical fingerprint of the sample and the internal standard after six rounds of baseline feature extraction (D). EMSC, Extended multiplicative signal correction. Abbreviations in the equation are as follows: Abs_n,pixel, Normalized pixel absorbance; c_i, coefficient of compound I; c_Abs,MMI, coefficient of membrane; Abs_i, spectrum derived from purified compound I; E, noise.