title: Determination of Nerve Agent Metabolites by Ultraviolet Femtosecond Laser Ionization Mass Spectrometry.
abstract: Nerve agent metabolites, i.e., isopropyl methylphosphonic acid (IMPA) and pinacolyl methylphosphonic acid (PMPA), were derivatized by reacting them with 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr) and were determined by mass spectrometry using an ultraviolet femtosecond laser emitting at 267 and 200 nm as the ionization source. The analytes of the derivatized compounds, i.e., IMPA-PFB and PMPA-PFB, contain a large side-chain, and molecular ions are very weak or absent in electron ionization mass spectrometry. The use of ultraviolet femtosecond laser ionization mass spectrometry, however, resulted in the formation of a molecular ion, even for compounds such as these that contain a highly bulky functional group. The signal intensity was larger at 200 nm due to resonance-enhanced two-photon ionization. In contrast, fragmentation was suppressed at 267 nm (nonresonant two-photon ionization) especially for PMPA-PFB, thus resulting in a lower background signal. This favorable result can be explained by the small excess energy in ionization at 267 nm and by the low-frequency vibrational mode of a bulky trimethylpropyl group in PMPA.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Akifumi
authors.initials: A
authors.lastname: Hamachi
authors.affiliation: Laboratory of Chemistry, Graduate School of Design, Kyushu University , 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Imasaka
authors.affiliation: Division of International Strategy, Center of Future Chemistry, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Division of International Strategy, Center of Future Chemistry, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Adan
authors.initials: A
authors.lastname: Li
authors.affiliation: Division of International Strategy, Center of Future Chemistry, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Totaro
authors.identifier: 0000-0003-4152-3257
authors.initials: T
authors.lastname: Imasaka