The Stellar MS is equipped with the Auto-Ready™ ion source, which is used exclusively for instrument calibration (not for sample analysis).

The Auto-Ready hardware uses ESI to generate calibrant ions, which are used to automatically characterize and calibrate the MS. Like the H-ESI source that is used for analysis, the Auto-Ready ESI source generates ions similar to H-ESI and Nanoelectrospray ionization (nanoESI or NSI) sources. A high-voltage current applied to a fine-tipped needle generates a fine mist of highly-charged droplets, which desolvate to create calibrant ions. Similar to the NSI source, no nebulizing gas or heat is applied to the needle. The ions are generated purely from the electric field.

The Auto-Ready ESI source operates at a relatively low flow rate of 1 µL/min, allowing the on-board calibrant vials to last for extended periods of time despite their small volumes. A special formulation of the Pierce™ FlexMix™ calibration solution is used for this application, which enables generation of calibrant species in both positive and negative polarities. Because Auto-Ready operates under much more restricted conditions than other ion sources (single solution composition, fixed flow rate, fixed sprayer position, and so on), much of its operation is controlled automatically by the instrument control software, simplifying the calibration process and user experience.

The Auto-Ready source has a second, dedicated ion transfer tube, that has a significantly smaller diameter than the main analytical transfer tube. As a result, the ion flux into the instrument from Auto-ready is significantly lower than that from H-ESI.

NOTE

Thermo Fisher Scientific recommends that you include a shutdown method at the end of every sequence that uses an LC workflow when scheduling Auto-Ready calibrations with the Self-Check feature. The Self-Check process automatically adjusts system settings, such as the source gases, temperature settings, and so on.

Include the following actions in the shutdown method:

  • Set the vaporizer temperature to under 20 °C
  • Set the LC flow rate to under 10 µL/min
  • Set source gases to minimal levels, which helps reduce source housing dryness