Flow Rates: 50µL/min. - 2mL/min.
Vaporizer Temp (°C): 400-550 (600 max)
Discharge Current (µA): 5 (20µA max.)
Sheath Gas Flow Rate (arb): 35-80
Auxiliary Gas: 0
Capillary Temp (°C): 250-350C
Tube Lens Offset (V): 30-60V
Ensure that the APCI probe is hot enough so that the spray shield is not dripping wet.
(Note: For me, always assume that works better at higher flow rates, higher flow rate means more solvent for plasma production. Position of corona discharge needle is critical for sensitivity.)
Steps for APCI Optimization
If analyte’s pKa is unknown, evaluate 3 pH regions in positive and negative ion modes.Acids – Negative Ion detection, adjust pH 2 units below pKa.
Decrease pH use formic acid , acetic acid, TFA.
Bases – Positive Ion detection, adjust pH 2 units above pKa.
Increase pH with NH4OH, TEA, TMA.
Adjust corona discharge voltage.
Adjust nebulization temperature.
Consider possible thermal decomposition of analyte.
