Mg. Bartlett et Kl. Busch, TRANSMISSION CHARACTERISTICS OF A RADIOFREQUENCY QUADRUPOLE FOR MS MS/, Analytical instrumentation, 21(3-4), 1993, pp. 123-140
Ion transmission through an RF-only quadrupole is affected by both the
frequency and voltage applied to the quadrupole. With a change in the
collision cell voltage, ion abundances for both precursor and product
ions are seen to vary in a modulated fashion. This pattern of ion abu
ndances has been described as quadrupole ''nodes'', with changes in io
n abundances within a factor of 2-4 from maximum to minimum abundance.
These nodes hamper MS/MS spectral reproducibility from instrument to
instrument and can camouflage trends observed in energy-resolved MS/MS
(ERMS/MS). We find ion abundance nodes to be present for both product
and precursor ions, and the collision energies at which the nodes max
imize appear to be unique to each mass.