Broad-Band Fourier Transform Quadrupole Ion Trap Mass Spectrometry

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• 作者：Manish Soni ; Vladimir Frankevich ; Mario Nappi ; Robert E. Santini ; Jonathan W. Amy ; and R. Graham Cooks
• 刊名：Analytical Chemistry
• 出版年：1996
• 出版时间：October 1, 1996
• 年：1996
• 卷：68
• 期：19
• 页码：3314 - 3320
• 全文大小：235K
• 年卷期：v.68,no.19(October 1, 1996)
• ISSN：1520-6882

文摘

Broad-band nondestructive ion detection is achieved ina quadrupole ion trap mass spectrometer by impulsiveexcitation of a collection of trapped ions of differentmasses and recording of ion image currents induced ona small detector electrode embedded in but isolated fromthe adjacent end cap electrode. The image currentsaredirectly measured using a simple differentialpreamplifier,filter, and amplifier combination and then Fourier analyzed to obtain broad-band frequency domain spectracharacteristic of the sample ions. The use of thedetectorelectrode provides a significant reduction in capacitivecoupling with the ring electrode. This minimizescouplingof the rf drive signal, which can saturate the front-endstage of the detection circuit and prevent measurementof the relatively weaker ion image currents. Althoughimpulsive excitation is preferred due to its broad-bandcharacteristics and simplicity of use, results are alsogivenfor narrow-band ac and broad-band SWIFT (stored wave-form inverse Fourier transform) excitation. Data usingargon, acetophenone, and n-butylbenzene show thataresolution of better than 1000 is obtained with adetectionbandwidth of 400 kHz. An advantage of nondestructiveion detection is the ability to measure a single-ionpopulation multiple times. This is demonstrated using argonasthe sample gas with an average remeasurement efficiencyof >90%. Tandem mass spectrometry experiments usinga population of acetophenone ions are also shown.