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?
