In this paper, the development of an automatic assessor is presented, both in MATLAB and in Excel, for an analytical exercise. In particular, the emulation of an interlaboratory exercise, using the analytical determination of phosphorus in a dry detergent, carried out in the laboratory by different groups of students, was selected as a case of study. The automatic assessor was used in the e-learning environment DOCTUS, which allows students to submit their results to a server to receive back immediately their mark and an indication of their possible mistakes. Using this approach enhances the learning experience of the laboratory work of students. The experience described in this article has been developed in the frame of the subject "Quality Control in Analytical Laboratories" corresponding to the chemistry degree at the University of Extremadura (Spain) along the academic courses from 2017/2018 to 2021/2022. The impact of the implemented tool on students' academic performance has been also addressed.