5975C GC/MS 219 ION HIGH

After cleaning the source on a 5975C GC/MS and performing atune, the 219 ion is high, roughly equal to the 69 ion, and sometimes greater. The response of 69 is normal (219 is high, 69 is not low). This instrument is used for volatiles analysis and now will not pass the required bromofluorobenzene tuning criteria, since the 173-177 bfb ions are too high relative to the bfb 95 base ion. 219 cannot be lowered enough through manual tuning. The source, quad and transfer line are at the proper temperatures. Any solution to this? Try re-cleaning?

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  • We still have the issue of 219 ion being the base peak instead of 69 on our 5975C used for EPA volatiles analysis. This occurs during atune and also the BFBAutotune. The only way we can get it to pass a BFB tune is to ramp the Entrance Lens Offset to lower 219 into the range it needs to be. Otherwise the 173 to 177 ions in BFB are too high. We are using the BFBAutotune routine modified to ramp the offset. Even though it generally passes, we would like to correct this issue. Any ideas?

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