Radiant energy – Ionic separation or analysis – Cyclically varying ion selecting field means
Reexamination Certificate
2006-01-31
2006-01-31
Lee, John R. (Department: 2881)
Radiant energy
Ionic separation or analysis
Cyclically varying ion selecting field means
C250S281000, C250S282000, C250S284000, C250S288000, C250S290000
Reexamination Certificate
active
06992285
ABSTRACT:
A method of and apparatus for analyzing a substance takes a stream of ions in said substance and supplies the ions to a collision cell including a quadrupole rod set for guiding the ions and a buffer gas. An RF voltage is applied to the quadrupole rod set to guide ions. An additional alternating current signal is applied to the quadrupole rod set at a frequency selected to cause resonance excitation of the secular frequency of a desired ion, whereby said desired ions are excited and undergo collision with the buffer gas causing fragmentation. The alternating current signal is then modulated, whereby periods in which said alternating current signal is applied alternate with periods in which said alternating signal is not applied. The ion spectrum after fragmentation is collected to generate one set of data for one spectrum, representative of the ion spectrum when the alternating current signal is applied, and another set of data for another spectrum, representative of the ion spectrum when the alternating current signal is not applied. These two spectra can then be subtracted.
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R.E. March, R.J. Hughes, “Quadrupole Storage Mass Spectrometry”, 1989, John Wiley & Sons, pp. 365-387.
Cousins Lisa
Thomson Bruce
Bereskin & Parr
Lee John R.
MDS Inc.
Vanore David A.
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