Applicability of Adduct Detection in Liquid Chromatography–Tandem Mass Spectrometry

Abstract

To investigate the process of analyte adduct formation with the components of the mobile phase in the negative electrospray ionization mode and to answer the question if the strategy of adduct identification/fragmentation is applicable for a bigger number of drugs, which meet the appropriate ionization conditions and compare the detection of appropriate analyte adducts to deprotonated analytes with tandem mass spectrometry, ten drugs containing carboxyl groups capable of negative electrospray ionization were chosen for appropriate experiments. The continuous infusion of captopril, fenbufen, gabapentin, ibuprofen, ketoprofen, naproxen, ramipril, salicylic acid, tiaprofenic acid, and 11-nor-9-carboxy-delta-9-tetrahydrocannabinol made the adduct identification/fragmentation experiments possible. The results achieved show that the adduct formation/fragmentation process can be used for LC–MS/MS analysis of drugs that meet the appropriate ionization conditions like the presence of a carboxyl group. It was also demonstrated that signal intensities achieved by the fragmentation of deprotonated drugs are in most cases higher than the signals connected with the fragmentation of appropriate adducts.