The laboratory tap water sample used for method performance evaluation and comparison, as well as a 50 mg/L SRFAS in methanol:ultrapure water 1:1, were employed. In order to take into account seasonal and geographical variations of fulvic acid content , the DOM composition of SRFAS was considered. Both solutions were run with the proposed LC-QTOF method, and full scan data were analysed. The average spectra acquired from 3. [M-H] -having a spectral intensity of less than 100 in both spectra were not included in the list, generating a m/z interval ranging from 187 to 612 Da. In this way, elemental compositions unlikely to generate features were excluded in order to avoid unnecessary computational burden.