title: Mechanical ion gate for electrospray-ionization ion-mobility spectrometry.
abstract: A novel ion gate for electrospray-ionization atmospheric-pressure ion-mobility spectrometry (ESI-IMS) has been constructed and evaluated. The ion gate consisted of a chopper wheel with two windows--one for periodic ion passage from the ESI source into the drift region and the other for timing and synchronization purposes. The instrument contained a 45.0 cm long drift tube comprising 78 stainless steel rings (0.12 cm thick, 4.90 cm o.d., 2.55 cm i.d.). The rings were connected together in series with 3.34-MOmega resistors. The interface plate and the back plate were also connected with the first and the last rings, respectively, of the drift tube with 3.34-MOmega resistors. A potential of -20.0 kV was applied to the back plate and the interface plate was grounded. The drift tube was maintained at an electric field strength of approximately 400 V cm-1. An aperture grid was attached to the last ring in front of a Faraday plate detector, center-to-center. Several sample solutions were electrosprayed at +5.0 kV with +500 V applied to the ion gate. Baseline separations of selected benzodiazepines, antidepressants, and antibiotics were observed with moderate experimental resolution of approximately 70.
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.forename: David C
authors.initials: DC
authors.lastname: Collins
authors.forename: Edgar D
authors.initials: ED
authors.lastname: Lee
authors.forename: Alan L
authors.initials: AL
authors.lastname: Rockwood
authors.forename: Milton L
authors.initials: ML
authors.lastname: Lee