Isomerization of ionized toluene and cycloheptatriene on resonant excitation in a quadrupole ion-trap mass spectrometer

✍ Scribed by Cecilia Basic; John R. Eyler; Richard A. Yost

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 371 KB
• Volume: 29
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210290612

✦ Synopsis

OMS Letters

Dear Sir,

Isomerization of Ionized Toluene and Cycloheptatriene on Resonant Excitation in a

Quadruple Ion-trap Mass Spectrometer Hart et al.' have reported evidence of differing degrees of isomerization of tolyl ions ([C,H,]', m/z 91) during various ion isolation methods in a quadrupole ion-trap mass spectrometer. In a recent collision-induced dissociation (CID) study of a series of small molecules conducted on a such a spectrometer in our laboratory, anomalous changes in the rate of dissociation of the m/z 92 molecular ions of both toluene (TOL + , [C,H ,CH 3] +*) and cycloheptatriene (CHT + , [C,H,]+') were observed as the resonant excitation time was increased [Fig. l(a) and (b)]. These changes are evidenced as plateaus in the breakdown curves and are seen using a variety of excitation potentials [Fig. 2(a) and (b)]. [The m/z 91 product ion curves for Fig. 2(a) and (b) are similar to those presented in Fig. l(a) and (b) and have been omitted for clarity.] To our knowledge, no previous report of quadrupole ion-trap mass spectrometry (QITMS) breakdown graphs exhibiting this anomalous behavior has been presented. Repli-30.80 '.OO k .rn C (u c .G 0.60 C 0 D 0.40 a N 0 0 c .-.-- g 0.20 0.00 0.0 2.0 4.0 Ion Voltage (mV,,) Time (ms) Slope (ms-') TOL+ 175 0.