Identification and Counting of Oxygen Functionalities in Aromatic Analytes Related to Lignin by Using Negative-Mode Electrospray Ionization and Multiple Collision-Activated Dissociation Steps

Identification and counting of different oxygen-containing functional groups in 40 small aromatic analytes, including a lignin monomer, was explored using a linear quadrupole ion trap (LQIT) mass spectrometer. The analytes were evaporated and ionized by negative-mode electrospray ionization (ESI). In an effort to cleave off all of the functionalities, one at a time, the deprotonated analytes were then subjected to multiple consecutive collision-activated dissociation (CAD) events until no more fragmentation was observed (up to MS5). In most cases, the number and types of functionalities could be determined. This approach was demonstrated to be feasible on the high-performance liquid chromatographic (HPLC) time scale. Hence, valuable structural information can be obtained for previously unknown aromatic analytes directly in complex mixtures, such as lignin degradation products.