Exact-mass library for pesticides using a molecular-feature database

An automated molecular‐feature database (MFD) consisting of the exact monoisotopic mass of 100 compounds, at least one exact mass product ion for each compound, and chromatographic retention time were used to identify pesticides in food and water samples. The MFD software compiles a list of accurate mass ions, excludes noise, and compares them with the monoisotopic exact masses in the database. The screening criteria consisted of ±5 ppm accurate mass window, ±0.2 min retention time window, and a minimum 1000 counts (signal‐to‐noise (S/N) ratio of ∼10:1). The limit of detection for 100 tested compounds varied from