Direct connection of an inductively coupled plasma and an ion trap mass spectrometer
- Pacific Northwest Lab., Richland, WA (United States)
The good sensitivity and tandem mass spectrometric capability of the quadrupole ion trap mass spectrometer (ITMS) has made it a useful instrumental technique for organic analysis. These same qualities might be useful for elemental analysis, including techniques like inductively coupled plasma mass spectrometry (ICP-MS). Two existing ITMS capabilities, prolonged ion injection and MS/MS could be immediately helpful. Long ion trapping times could be advantageous for determination of trace level elements and isotopes. MS/MS could be used to resonantly excite and collisionally dissociate polyatomic ions that arise from the plasma gas (argon) and sample matrix (water, various acids, and high concentration sample components) and that are nominally isobaric with analyte ions below 81 m/z. In addition, slow scanning techniques suggested that greater mass resolution was possible. The most direct approach would be to couple the ICP and ITMS directly with minimal intervening vacuum interface and ion optic hardware. However the limited ion capacity of the ion trap before onset of significant space charge effects and the intense Ar ion current from the plasma raised concerns that the direct connection would quickly fill the trap with Ar ions, rendering the trap useless for detection of trace ions. Therefore a linear quadrupole was employed between the vacuum interface and the ion trap to act as as an RF-only high pass filter, an RF/DC selective mass filter, or as a notch filter to reduce or eliminate the Ar and matrix ion currents to the ion trap.
- OSTI ID:
- 210576
- Report Number(s):
- CONF-9505261--
- Country of Publication:
- United States
- Language:
- English
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