title: Elimination technique for alkali metal ion adducts from an electrospray ionization process using an on-line ion suppressor.
abstract: The effects of an on-line ion suppressor device on alkali metal ion adduct formations of the model compound tacrolimus were investigated. The base peak ion in the positive ion ESI-MS spectrum of tacrolimus was a sodium ion adduct, [M+Na](+). On the other hand, an ammonium ion adduct, [M+NH(4)](+), was the base peak ion in the full-scan mass spectrum of tacrolimus with a cation-exchange suppressor resin, and both [M+Na](+) and [M+K](+) were eliminated. These results indicate that the combination of an on-line ion suppressor with ESI-MS is a simple and effective technique that eliminates undesirable alkali metal ion adduct formations in the positive-ion mode.
authors.affiliation: Department of Applied Chemistry, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamatecho, Suita, Osaka 564-8680, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Nozaki
authors.forename: Akira
authors.initials: A
authors.lastname: Tarui
authors.forename: Issey
authors.initials: I
authors.lastname: Osaka
authors.forename: Hideya
authors.initials: H
authors.lastname: Kawasaki
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Arakawa
mesh_terms: D016477:Artifacts; D007166:Immunosuppressive Agents / Q000737:chemistry; D008672:Metals, Alkali / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D016559:Tacrolimus / Q000737:chemistry; D053719:Tandem Mass Spectrometry
chemical_list: D007166:Immunosuppressive Agents; D008672:Metals, Alkali; D012964:Sodium; D016559:Tacrolimus