OBJECTIVE or GOAL
Test for GC transfer line air leaks or source insulator problems on the AutoSpec.
- AutoSpec Premier
- 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
- Tune the instrument to 10,000 resolution with the accelerating voltage set to 8 kV, and optimize/note the Ion Repeller/Focus 1 values.
- Set the accelerating voltage to 6 kV, optimize Y Focus, and then re-optimize/note the Ion Repeller/Focus 1 values.
- 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).
- 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.