Hello dear, you can make the normalization by using an internal signal that it changes very little in its intensity. It can be easily detected in your spectra, usually this signal appear a low wave number.

Mr. Kadja,

The quantification by IR using KBr pellets technique is based on internal standard, generally. Otherwise, you need a parallel independent measurements by other method allowing you to quantify your compound in the KBr pellet, and then to normalize all FTIR spectra according this "reference" spectrum. Those independent methods can be UV-VIS if your analyte is chromophore or ESI-MS/MS (applicable to any analyte). It is needed just to dissolve quantitatively your KBr pellets, after the corresponding FTIR measurements, in suitable solvent and to measure their absorption and MS spectra.

The matrix effect of KBr you can quantify measuring UV-VIS or MS spectra of a KBr pellet without presence of your analyte.