title: Rapid analysis of polychlorinated biphenyls in the gas phase with resonance-enhanced two-photon ionization: optimal injection of ions into the ion-trap storage/time-of-flight mass spectrometer.
abstract: LI-IT-TOFMS (laser ionization/ion-trap storage/time-of-flight mass spectrometry) is expected to be a powerful tool for environmental monitoring. In the research reported here, real-time LI-IT-TOFMS measurements were carried out on gaseous 2-4 chlorinated PCBs in order to evaluate the applicability of an environmental monitoring method. With respect to ion-trap storage for PCBs, we found that the effect was due to the driving RF voltage on the ring electrode in the ion trap. For PCBs ions produced by laser irradiation, we observed that it was more efficient to reach the center of the ion trap by using a gated RF voltage rather than by using a continuous RF voltage. The ion trajectories in the ion trap were simulated by SIMION 7.0. We found that the voltage of the exit end cap electrode affected both the number of ions trapped and the orbit of ions inside the trap cell. Optimization of this parameter was performed using both simulated and experimental results. The achievable PCBs sensitivity for real-time (1 min) measurement using the LI-IT-TOFMS method was found to be in the pptV range (<0.01 mg/m3N) by means of a comparison with the conventional gas sampling/GS-MS method. A satisfactory proportional relationship was confirmed between the laser-based and conventional results.
authors.affiliation: Nagasaki R&D Center, Mitsubishi Heavy Industries Ltd, Japan. shinsaku_dobashi@mhi.co.jp
authors.forename: Shinsaku
authors.initials: S
authors.lastname: Dobashi
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kira
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Tanaka
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Izawa
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Deguchi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kubota
authors.forename: Akihide
authors.initials: A
authors.lastname: Wada
authors.forename: Michikazu
authors.initials: M
authors.lastname: Hara
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D005740:Gases / Q000032:analysis; D017785:Photons; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation* / Q000379:methods*; D013997:Time Factors
chemical_list: D005740:Gases; D011078:Polychlorinated Biphenyls