An investigation of the vapor phase concentration is performed using the infrared extinction technique on an ethanol spray injected into a heated environment. Experiments are carried out on a confined geometry behind a real-scale injection system. It is composed of a pressure atomizer and an air swirler. The first part of the paper describes the fundamentals of the measurement technique and the experimental procedure. To obtain spatially resolved results, a deconvolution procedure based on the Abel algorithm and Tikhonov regularization is developed. In the second part, the steady measurements performed downstream from the injector provide the radial evolution of the integral vapor molar concentration for various different air temperatures. In addition, a spectral analysis of time resolved recordings shows that the liquid droplets are moving with the frequency of the precessing vortex core. In the last part of the paper, the local measured values of concentration are compared to the numerical ones. First, the numerical approach is validated for the pure gaseous and two-phase flow behavior. Second, the experimental and numerical vapor molar concentrations are presented and discussed.