quadrupole mass filter


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quadrupole mass filter

A term of art used in mass spectrometry for a specific combination of direct current (DC) and radiofrequency (RF) voltages which, when applied to four parallel metal rods, creates a filtering device that limits the transmission of ions to a certain defined m/z value. Changing the ratio of the voltages changes the m/z value of ions that pass through to the detector. The quadrupole mass filter can also be operated in other modes, such as passing a mass range of ions to the detector. If only the RF portion of the voltage is applied to the rods, virtually all ions pass to the detector.
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References in periodicals archive ?
The CIS ionizer sits on top of the quadrupole mass filter and consists of a short, gas-tight tube with two small openings for the entrance of electrons and the exit of ions.
The [DELTA]M can be measured at the half-height of the mass peak or at 10% of the peak height, depending on the inherent shape of the mass peak in the mass analyzer (e.g., quadrupole mass filter vs magnetic /electric sector).
Nevertheless, several groups have reported that the QIT has full-scan detection limits similar to those of a quadrupole mass filter (QMF) operated in the selected-ion monitoring (SIM) mode for drug testing [4,5].
Each instrument in the range features the MAX-HM quadrupole mass filter assembly, a precision-machined 9.5 or 19 mm rod set with improved RF-only pre-and post-filter stages, stabilizing rods and high power RF generators that, in combination, deliver enhanced transmission, resolution and abundance sensitivity characteristics at high masses.
The quadrupole mass filter assembly can also outgas.