Application of the Maxwell Garnett effective medium model and of the coated sphere model is examined in the context of analysis of light scattering/absorption data from inhomogeneous particulates. It is shown that particle optical inhomogeneity may not in general be neglected when light scattering/absorption data are to be analysed for volume fractions of particulates. Furthermore, the present results demonstrate that, in visible wavelengths for particles less than 100 nm in diameter, the Maxwell Garnett effective medium model and coated sphere model may yield equivalent results for extinction efficiencies and particle volume fractions.