Upon completion of the PCI mode methane tune, a note appeared on the bottom saying "one or more peaks not detected. CI Reagent ratio unknown." What should I do next? Thanks!
This is from the CI troubleshooting manual:
Reagent gas ion ratio is difficult to adjust or unstable
1. The interface tip seal is incorrectly placed, damaged, or missing. Inspect the interface tip seal. If necessary, remove and reinstall it to ensure a good seal with the CI ion source. Replace it if it is damaged. Install it if it is missing.
2.Residual air and water in the MSD or in the reagent gas supply lines Run the methane pretune. Air will appear as a peak at m/z 32 and excessive water as a peak at m/z 19 > m/z 17. If either of these conditions is present, purge the reagent gas supply lines and bake out the MSD. See "To Clean the Reagent Gas Supply Lines" on page 141. Continued presence of a large peak at m/z 32 may indicate an air leak. After correcting the problems, you may need to clean the ion source.
3.Air leak Run Methane Pretune (in PCI). Large peak at m/z 32 indicates air in the system. Check for and correct any leaks. See "Air Leaks" on page 64.
4.The reagent gas supply is at the wrong pressure. Check the regulator on the reagent gas supply. It should be adjusted t o 20 psi (140 kPa).
4.A leak in the reagent gas delivery path. This is especially likely if you have set the methane flow much higher than normal and the ratio is still too low. Check the reagent gas path. Tighten fittings.
5. The CI ion source is dirty. Clean the ion source
Thank you very much!!! We’ve switched over to EI mode, but I will keep this in mind when going back to CI.
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