Development of an Atmospheric Pressure Ion Mobility Spectrometer–Mass Spectrometer with an Orthogonal Acceleration Electrostatic Sector TOF Mass Analyzer

Abstract

Recently developed ion mobility mass spectrometer is described. The instrument is based on a drift tube ion mobility spectrometer and an orthogonal acceleration electrostatic sector time-of-flight mass analyzer. Data collection is performed using a specially developed fast ADC-based recorder that allows real-time data integration in an interval between 3 and 100 s. Primary tests were done with positive ion electrospray. The tests have shown obtaining 100 ion mobility resolving power and 2000 mass resolving power. Obtained for 2,6-di-tert-butylpyridine in electrosprayed liquid samples during 100 s analysis and full IMS/MS data collection mode were 4 nM relative limits of detection and a 1 pg absolute limit of detection (S/N=3). Characteristic ion mobility/mass distributions were recorded for selected antibiotics, including amoxicillin, ampicillin, lomefloxacin, and ofloxacin. At studied conditions, lomefloxacin forms only a protonated molecule-producing reduced ion mobility peak at 1.082 cm(2)/(V s). Both amoxicillin and ampicillin produce [M + H](+), [M + CH3OH + H](+), and [M + CH3CN + H](+). Amoxicillin shows two peaks at 0.909 cm(2)/(V s) and 0.905 cm(2)/(V s). Ampicillin shows one peak at 0.945 cm(2)/(V s). Intensity of protonated methanol containing cluster for both ampicillin and amoxicillin has a clear tendency to rise with sample keeping time. Ofloxacin produces two peaks in the ion mobility distribution. A lower ion mobility peak at 1.051 cm(2)/(V s) is shown to be formed by [M + H](+) ions. A higher ion mobility peak appearing for samples kept more than 48 h is shown to be formed by both [M + H](+) ion and a component identified as the [M + 2H + M](+2) cluster. The cluster probably partly dissociates in the interface producing the [M + H](+) ion.

Investigation by simulation of the RF carpets for the transport of ions at atmospheric pressures

“…It is more important for focusing of the ions at atmospheric pressure in ion mobility spectrometry/mass spectrometry (IMS/MS). Such combinations were reported for ion mobility spectrometer/time-of-flight mass spectrometer (IMS/TOF MS), [6][7][8][9] ion mobility spectrometer/quadrupole mass spectrometer (IMS/QMS), 10 and for field asymmetric ion mobility spectrometer/mass spectrometer (FAIMS/MS) 11,12 and for aspiration ion mobility spectrometer/mass spectrometer. 13 For all the combinations, a 90%-99% of the losses occur at inlet of MS.…”

A computer model of comprehensive modeling of the laser time-of-flight analyzer

“…[4][5][6][7][8] Modeling of mass analyzers is the first stage of timeof-flight mass spectrometers design process. At this stage, the ion-optical properties are determined, [9][10][11][12] and the possibility of achieving required values of resolution and transmission is studied. However, properties of the ion source, detector, and recorder can affect the parameters.…”

Novel approach to constructing laser ionization elemental time-of-flight mass spectrometer

“…A new geometry for the single particles laser TOF mass spectrometry was presented in Murphy. 46 The geometric construction (sTOF) includes two opposing electrostatic sectors of about 255 each similar to that described in Sysoev et al 47,48 and straight sections with a length appropriate to the turns. The resulting geometry folds into a compact space.…”