We explore the feasibility of estimating primary cosmic ray composition at ultra high energies from the study of lateral age parameter of Extensive Air Showers (EAS) at ground level. Using different types of lateral distribution functions, we fit the
particle density of simulated EAS to find the lateral age parameter. We discuss the chemical composition calculating the merit factor for each parameter distribution. The analysis considers three different primary particles (proton, iron and gamma), four different zenith angles (0{deg}, 15{deg}, 30{deg} and 45{deg}) and three primary energies (10^{17.25} eV, 10^{17.50} eV and 10^{17.75} eV).
