Hi, has anyone got a method for THC acid in either negative or positive mode for a 6470 LCMS. I have a drug screen method with 65 compounds, (Amphetamines, Opiates, Cocaines, Cathinones etc) and THC acid is the only one that is not ionizing well, even in negative mode. We see about 10,000 cps for 7.5 ng/mL THCA. We use an 5mM Amm. Acetate MPA, and Acetonitrile based MPB. I've tried using the MRMs available in the ForTox database, with limited success. Thanks.