The Capillary Current is a read-only value in the Tune > Source Section.
The normal values for Capillary Current in API-ES depend on the Capillary Voltage setting, solvent flow rate, and solvent conductivity. In APCI, the corona current and vaporizer temperature may also impact the Capillary Current. This makes it difficult to specify a range for proper Capillary Current. For the standard calibrant solutions for API-ES and APCI, the Capillary Current is typically in the range of 70 to 110 nA.
The normal values for Capillary Current in MMI-ES depend on the solvent flow rate, charging voltage and source temperature. The Capillary Current may be measured using an ammeter attached to the nebulizer. When operating in MMI-ES ionization mode, essentially no chamber or Capillary Current is observed. The Capillary Current is typically in the range of near zero to 10 microamps.
In MMI-APCI mode, the Capillary Current is affected by similar solvent and source parameters. However, a significant amount of the ion current is going to dissipate at the counter electrode. The Capillary Current is typically one half that of the MMI-ES mode, near zero to 5 microamps.
You should monitor the typical Capillary Current or a given analysis or type of analysis, and if the current changes significantly, first clean the spray chamber, and if the problems persist, clean the capillary.
See Also