An identification workflow was developed to identify unknown carboxylic acids based on the phenyl bromine ion pair of derivatives fragments (Figure ). The product ions from AIF scans were matched against the isotopic pattern of m/z 169 and 171, with an abundance ratio of approximately 1:1. Accordingly, the carboxylic-BNMA derivative peaks were integrated with the full-MS chromatogram corresponding to the integrated AIF LC peaks. Based on the merged full-MS chromatographic peaks, a derivatives m/z list was summarized and filtered with a signal-to-noise ratio above 3. The derivatives were annotated using Formularity. The original carboxylic acid formulas were computationally generated by removing the labeling group using an in-house developed Python script. The PyC2MS software was used for the treatment and visualization of carboxylic acid data. Detailed information regarding the Formularity and computational removal of 4-BNMA label are provided in the supporting information. The CIA assigns accurate mass using an assisting database (CIA DB) and formula expansion features based on building blocks (CH2, H2, O2, or homologs series). The universal CIA DB comprises over 29 million pure hypothetical formulas limited to CHNSO and validated based on the seven golden rules, having a monoisotopic mass below 1500 Da. Featuring CIA, the Isotopic Pattern Algorithm (IPA) function was developed for annotating compounds containing multiisotopic elements. In this study, we compiled an in-house IPA DB containing 2.9 million formulas based on a subset of the CIA DB, extracting formulas with 2 -6 oxygen atoms (corresponding to mono-, di-and tri-carboxylic acids). The list of formulas was derivatized in-silico, and the isotope peak pattern of the resulting formula was calculated using Ecipex software. Full details of the CIA DB transformation and IPA DB compilation are given in the supporting information.