After alignment, the total number of unfiltered features generated by analysing the same laboratory sample in triplicate with the proposed SAX-SPE method was, on average, less than a quarter of that generated with the WAX-based SPE method (16,064 versus 67,603 features, n=3). Features generated by sample preparation, mobile phases and instrument were successfully removed using both blank and repeatability filters. Figure shows the difference in number, m/z and intensity of features in the laboratory sample using both extraction approaches after application of blank and repeatability filters. Consequently, this feature reduction approach was applied to all 10 water samples collected from across London using the SAX-SPE method. On average across all samples, 16,638 features were generated in the raw dataset (RSD = 7 %), 7,371 were left after the alignment and repeatability filters were applied (RSD = 5 %), and 3,930 left after the blank filter (RSD = 9 %). An additional 19 % of the remaining features were removed on average by applying the DOM filter, down to 3,176 on average (RSD = 10 %). By comparison, the WAX method generated on average 7,543 features in the sample tested in triplicate after all filters were applied. For the SAX-SPE method, subsequent library matches removed with the application of DOM filter were on average 29 per sample (n=6): isotopic composition, peak shape and DIA MS/MS spectra of all removed features returning a library match showed no potential false negative results.