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How to test for GC transfer line air leaks or source insulator problems on the AutoSpec - WKB64335

Article number: 64335

OBJECTIVE or GOAL

Test for GC transfer line air leaks or source insulator problems on the AutoSpec.

ENVIRONMENT

  • AutoSpec Premier
  • AutoSpec
  • SIR Voltage Calibration routine resolution failure
  • Dioxin/PCB ratio target ion ratio failure
  • Target Ion/Internal Standard ion ratio failure
  • SIR Voltage experiment sensitivity failure

PROCEDURE

  1. Tune the instrument to 10,000 resolution with the accelerating voltage set to 8 kV, and optimize/note the Ion Repeller/Focus 1 values.
  2. Set the accelerating voltage to 6 kV, optimize Y Focus, and then re-optimize/note the Ion Repeller/Focus 1 values.
  3. Possible findings:
    • If the Ion Repeller/Focus 1 remains approximately the same (i.e., there is no significant improvement in the signal intensity), there are no significant GC transfer air line leaks or problems with the source housing insulators.
    • If both optimization points for the Ion Repeller/Focus 1 change, there is a GC transfer line air leak.
    • If only the optimization point for the Focus 1 changes, there is a source insulator problem (outer source, inner source, degussits, or other).

ADDITIONAL INFORMATION

  • This test must be done at high resolution; false positive results can be seen at low resolution.
  • The test should be carried out after any maintenance.
  • The test should be carried out if SIR Voltage Calibration resolution drops markedly (>2.5k), depending on start (lowest) and end (highest) mass in the function being calibrated (general rule for a function mass range = start mass x 1.6).
  • A GC Transfer air leak can also result from too much air being introduced into the septum tank along with reference solution (no actual air leak exists).
  • The test is >95% effective.
  • There may be an air leak elsewhere in the source housing, but this would not affect any data being acquired.

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