The estimation of adsorption isotherm parameters is vital to the design, scale-up and optimization of adsorption and chromatographic separation processes. Based on the equilibrium theory of chromatography a method to estimate competitive Langmuir isotherm parameters by measuring the retention time of the two shock fronts from pulse injections of binary mixtures has been developed. This method offers several advantages compared to the available techniques for isotherm measurements. Firstly, only the retention times of the shock fronts are required, and hence this method effectively eliminates the need for detector calibration. Secondly, by using injections of binary mixtures, it eliminates the need for the availability of pure components. Thirdly, since the experiment involves a pulse injection it reduces the amount of solute needed for isotherm determination. Finally, since the estimation procedure involves the calculation of the retention times of the shock fronts alone, i.e. without calculating the entire elution profile, the computational time required is significantly reduced allowing for rapid parameter estimations. The method has been tested on several published results and it has been found that parameters obtained from this "retention time" method are comparable to those estimated from more rigorous techniques such as the inversion method. The effectiveness of this method in rapid determination of isotherm parameters is highlighted, and its limitations with respect to aspects such as column efficiency are discussed.