Carbohydrate and steroid analysis by desorption electrospray ionization mass spectrometry

摘要

Desorption electrospray ionization mass spectrometry (DESI-MS) is applied to the analysis of carbohydrates and steroids; the detection limits are significantly improved by the addition of low concentrations of salts to the spray solvent. Desorption electrospray ionization (DESI) is an ambient desorption ionization technique which has been applied to rapid in situ analysis with minimal or without any sample pretreatment. Due to its speed, ease of use and high salt tolerance, DESI is becoming a useful tool in forensic, pharmaceutical and biological applications. Analytes present on the target substrate are dissolved in the spray solvent and released from the wet sample surface into the secondary microdroplets formed by high velocity charged droplet impact. Optimum performance in DESI is usually obtained for polar analytes that can readily be proto-nated or deprotonated. However, many biologically important molecules, including carbohydrates and steroids, do not have these characteristics. They may be successfully characterized by other mass spectrometry methods but direct ambient analysis is highly desirable.