In the data pre-processing step in metaboanalyst, “Processing MS peak list data,” metaboanalyst suggests a mass tolerance of 0.25 m/z, specifically for LC-MS peaks. However, a mass tolerance of 0.025 is pre-populated in the text box. How can I best choose the optimal mass tolerance for my LC-QToF data? I also thought m/z had no units, however I am also reading that it could equate to daltons or ppm or percentage. Do we know what units metaboanalyst is using? I appreciate your thoughts on this!