I am trying to run dioxin and furans on a XEVO-TQ-XS in APGC mode and see most frequent ion abundance ratio failures on low level standards. The same analysis has been performed on the same instrument in the past without any issues.

Is this related to mass calibration? Or would the corona pin position play a role in this?

Recently changed the corona pin and repositioned. Responses are 5X lower than previous analysis. Can you please share your experience related to this issue? Thank you!