Quantitative analysis of dextran in rat plasma using Q-Orbitrap mass spectrometry based on all ion fragmentation strategy

Dextran is a biocompatible glucose-based polymer that is widely used clinically as a plasma volume expander, anti-thrombotic agent, macromolecular carrier, peripheral blood flow enhancer, and artificial tears promoter. Because dextran has polydisperse molecular weights and tends to produce innumerable multi-charged precursor ions in the ion source, it is difficult to analysis this polymer using conventional liquid chromatography mass spectrometry. In this assay, all ion fragmentation strategy is used to solve this problem by allowing all dextran precursor ions generated in the ion source to enter the collision cell. Then serial dextran-specific fragments can be effectively generated from all precursor ions by higher energy collision dissociation and scanned by Orbitrap detector. These high resolution fragment ions provide high specificity and sensitivity for the quantitation of dextran in rat plasma. Here, we report a new quantitative method using size exclusion chromatography combined with Q Exactive mass spectrometry based on an all ion fragmentation strategy. Assay validation showed that this method is linear over the concentration range from 3 to 300 μg/mL. Our approach has been successfully applied to a pharmacokinetic study of dextran in rat and will promote the development of studies with other polysaccharides.