good day. I'm trying to better understand recent observations involving analysis of a paralytic shellfish toxin (NeoSTX) using a Sciex API4000, HILIC column and mobile phase containing 15 mM ammonium formate, 5% methanol and 85% ACN + 0.1% formic acid. A method was previous developed and used with some success in our lab but sensitivity was recently lost. Further investigation lead to salt deposits visible on the electrode/capillary tip. Pressure through mass spec electrode/capillary suggested blockage (electrode has since been replaced). Replacement of the electrode and thorough cleaning of the orifice/Q0 failed to yield better sensitivity.
Test solutions contain NeoSTX in ACN + 0.1% FA:buffer (80:20).

Any insight that you could provide regarding analysis of paralytic shellfish toxins, HILIC columns, use of Ammonium formate buffers and the potential precipitation of buffer salts in high organic (80% ACN) and the effect on final sample pH would be greatly appreciated.