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Transmission characteristics of a radio‐frequency‐only quadrupole gas‐collision cell at high axial energies in a hybrid tandem mass spectrometer
Author(s) -
Alexander A. J.,
Dyer E. W.,
Boyd R. K.
Publication year - 1989
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290031013
Subject(s) - chemistry , collision , quadrupole , mass spectrometry , triple quadrupole mass spectrometer , collision induced dissociation , tandem , range (aeronautics) , ion , quadrupole mass analyzer , atomic physics , transmission (telecommunications) , tandem mass spectrometry , analytical chemistry (journal) , physics , selected reaction monitoring , telecommunications , materials science , computer security , organic chemistry , chromatography , computer science , composite material
Collision induced dissociation (CID) experiments using RF‐only quadrupole collision cells normally employ laboratory‐frame collision energies E lab of a few tens of eV. Difficulties in inducing CID reactions for larger precursors (> 600–800 Da) can be attributed in part to collision energies, in the appropriate centre‐of‐mass reference frame, which are too low. Attempts to overcome this problem by using values of E lab in the range of a few hundreds of eV have been largely unsuccessful. The present work shows that a major reason for this lack of success has been an inability of the instruments used to fulfil the focusing requirements of an RF‐only quadrupole cell for such precursors, and their higher mass fragments, in this range of values for E lab . A simple modification permitting use of much higher values of the RF amplitude has been shown to permit the collision cell to be operated so that the ion‐beam profile at the entrance aperture is imaged at the exit; improvements in precursor transmission efficiency by up to two orders of magnitude are thus obtainable. Examples of corresponding improvements in fragment‐ion spectra of a test octapeptide are also demonstrated. The principal drawback of this approach concerns the poor transmission for low‐mass fragments near the stability cut‐off (Mathieu parameter q u > 0.91); reasons for the non‐zero transmission efficiency for fragments with q u > 0.91 are discussed, together with methods for alleviating the low‐mass transmission problem.