@article {2402,
	title = {LINEAR QUADRUPOLES IN MASS SPECTROMETRY},
	journal = {Mass Spectrometry Reviews},
	volume = {28},
	number = {6},
	year = {2009},
	note = {ISI Document Delivery No.: 515CWTimes Cited: 5Cited Reference Count: 145Douglas, D. J.},
	month = {Nov-Dec},
	pages = {937-960},
	type = {Review},
	abstract = {The use of linear quadrupoles in mass spectrometry as mass filters and ion guides is reviewed. Following a tutorial review of the principles of mass filter operation, methods of mass analysis are reviewed. Discussed are extensions of quadrupole mass filters to higher masses, scanning with frequency sweeps of the quadrupole waveform, operation in higher stability regions, and operation with rectangular or other periodic waveforms. Two relatively new methods of mass analysis the use of "islands of stability" and "mass selective axial ejection" are then reviewed. The optimal electrode geometry for a quadrupole mass filter constructed with round rods is discussed. The use of collisional cooling in quadrupole ion guides is discussed along with ion guides that have axial fields. Finally, mass analysis with quadrupoles that have large distortions to the geometry and fields is discussed. An Appendix gives a brief tutorial review of definitions of electrical potentials and fields, as well as the units used in this article. (C) 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:937-960, 2009},
	keywords = {2ND STABILITY REGION, axial fields, AXIAL-FIELD, CHARGED-PARTICLE, COLLISION-INDUCED DISSOCIATION, distorted fields, FRINGING FIELDS, ion guide, ION OPTICAL-PROPERTIES, linear, mass filter, mass scans, multipoles, OCTOPOLE FIELDS, QUADRUPOLE, quadrupole excitation, RADIO-FREQUENCY, RESOLUTION, SEPARATION MODE, STABILITY, TRAJECTORIES, VOLTAGE COMPONENT},
	isbn = {0277-7037},
	url = {<Go to ISI>://000271445200005},
	author = {Douglas, D. J.}
}
@article {4246,
	title = {Ion source emittance influence on the transmission of a quadrupole operated in the second stability region},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {9},
	number = {10},
	year = {1998},
	note = {ISI Document Delivery No.: 121NBTimes Cited: 6Cited Reference Count: 19},
	month = {Oct},
	pages = {1074-1080},
	type = {Article},
	abstract = {The variation of transmission (T) with resolution (R) has been calculated for a quadrupole mass filter operated in the second stability region with Mathieu parameters q = 7.547 and a = 0 to 0.02995. The fringing fields at the entrance to the quadrupole, which can be strongly defocusing, and which can dramatically reduce the acceptance, have been included in the calculation. Even in the absence of fringing fields, at a resolution of 10,000 the acceptance in the x and y directions is less than 2 x 10(-4) pi r(0)(4) f(2) which is about 10(-3) of the acceptance in the first stability region at low resolution. Because the source emittance can strongly effect the T(R) behavior, the calculation of ion transmission has been done for two source emittances that correspond to different degrees of focusing of ions into the quadrupole. The T(R) characteristics for two realistic source emittances give behavior markedly different from the decrease in acceptance with increasing resolution which previously has been used as a measure of the quadrupole transmission. Comparisons of the calculated transmission losses with increasing resolution to earlier experimental results obtained with an inductively coupled plasma source show good agreement provided an emittance which corresponds to ions being tightly focused into the quadrupole is used. The calculation demonstrates that up to a resolution at half height of 7000 in the experiment, the transmission losses were a result of the decreasing quadrupole acceptance. At higher resolution the experimental transmission was limited by either the residence time of the ions in the quadrupole or the rod quality. It is also shown that the strong defocusing effects of the fringing fields at the entrance of the quadrupole can be largely overcome by accelerating the ions through these fields and then decelerating the ions in the quadrupole. (C) 1998 American Society for Mass Spectrometry.},
	keywords = {ANALYZER, mass filter, SEPARATION MODE, SPECTROMETER},
	isbn = {1044-0305},
	url = {<Go to ISI>://000076019000011},
	author = {Douglas, D. J. and Konenkov, N. V.}
}
