Data evaluation of mass spectrometric raw data is an essential step to obtain high-quality results. In our days an exorbitant amount of raw data are produced in analytical (bio)chemistry due to the utilization of sophisticated experimental setups. The recently published free software Achroma has been developed to overcome increasing data processing challenges by providing the possibility of a comprehensive data analysis (http://openmasp.hswt. de/pages/project/achroma.php). To illustrate (a-)typical data evaluation, an online coupled continuous flow system hyphenated with mass spectrometric detection was applied to investigate enzymatic activity changes in the presence of regulatory molecules and alternative substrates. The extended software strategy, the processing as well as evaluation of data is presented in detail based on enzymatic assays of intestinal alkaline phosphatase (iAP) and acetylcholine esterase (AChE). Different Achroma data evaluation modules enabled a high quality analysis. This included the elucidation of enzymatic substrate preferences by means of the calculation of negative and positive peak areas as well as the identification of an inhibitory molecule by comparing different mass spectra with regard to their overall composition. The possibility of an automatically performed validity control to monitor the systems robustness furthermore emphasized the usefulness of Achroma software regarding its applicability in the area of 'functional proteomics' data handling