We present an experimental investigation of ignition delay times of model fuels of pure iso-octane and n-heptane as well as of a mixture consisting of iso-octane (80%) and n-heptane (20%) by liquid volume for different fuel qualities. The purpose of this survey is to advance the understanding of ignition time chemistry using shock-tube experiments. For the mixture, to our knowledge, only the data of Fieweger et al. are available so far. Thus, it is helpful to have a new supporting data for comparison and to study the influence of fuels on different purity levels on ignition delay times. The experiments are performed in a high-pressure shock-tube at a pressure p = 40 bar and a constant equivalence ratio of f = 1.0. The comparison of ignition delay data of the pure substances with literature [1-3] under similar conditions shows good agreement.