Development of an atmospheric pressure ion mobility spectrometer-mass spectrometer with an orthogonal acceleration electrostatic sector tof mass analyzer. Analytical Chemistry Volume 85, Issue 19, 1 October 2013, Pages 9003-9012

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 cm2/(V s). Both amoxicillin and ampicillin produce [M H] , [M CH3OH H] , and [M CH3CN H] . Amoxicillin shows two peaks at 0.909 cm2/(V s) and 0.905 cm2/(V s). Ampicillin shows one peak at 0.945 cm2/(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 cm2/(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.
Indexed keywords
Data collection; Ion electrospray; Limit of detection; Limits of detection; Mass analyzers; Mass resolving power; Orthogonal acceleration; Time-of-flight mass analyzer