Abstract The distribution of small molecules in dry latex films is the result of driving forces competing to displace these molecules at the interfaces or to retain them distributed inside the film. In order to provide a better insight into the process leading to segregation of surfactant molecules, confocal Raman spectroscopy was used. This technique was powerful in the quantitative determination of the distribution profiles of small molecules, namely sodium dodecyl sulfate (SDS) and sulfate anion (SO 4 2−), active in Raman mode, in the overall thickness of polymeric films. The concentration of the SO 4 2− ion is higher at the film/substrate interface than in the bulk whereas the film/air interface exhibits a depletion, which propagates at 50 μm from the surface in the film thickness. An enrichment of SDS is found at both interfaces; and aggregates of small molecules inside the film were detected for both SO 4 2− and SDS.