Matrix dependent neutralization has been studied by 2.5 keV Ne + ions scattered from Ga and As atoms implanted into various substrates. Porportionality between ISS signal and atomic content is found for a wide range of concentrations. For a set of III-V compound semiconductors a quantitative approach is demonstrated, enabling absolute determination of surface composition in multi-heteroepitaxial films as well as their in-depth control in the vicinity of interfacial regions. Preliminary classification is given concerning the validity of ISS quantitative analysis. Besides, a method for examining compositional changes due to preferential sputtering is outlined.