3-8 ESI and ESCi Modes of Operation
4. Click OK.
5. In the MassLynx Tune window, click Ion Mode > ESCi+.
6. Select box numbers 1 and 2, clear box numbers 3 and 4 (above the peak
display).
7. In row 1, set Ion Mode to ES.
8. In row 2, set Ion Mode to APcI.
9. In each row, set Mass to 42 and Span to 5.
10. Start an infusion of 80:20 acetonitrile/water.
11. Use the vernier probe adjuster to ensure that the ESI probe tip is
pointing approximately mid-way between the tips of the sample cone
and corona pin.
12. On the Tune window, observe the 42 Da peak in the ES+ and APcI+
peak displays, and increase the values of Capillary (kV) and Corona
[(µA) in the current mode or kV in the voltage mode] to produce the most
intense ESI+ and APcI+ signal.
13. Use the vernier probe adjuster to gradually move the probe
bi-directionally to determine the best position for both the ESI+ and
APcI+ signals.
Tip: You can find a position between the two modes that yields a
relatively optimized signal.
14. To determine whether you have discrete ionization in the ESI or APcI
mode, set the Capillary parameter to 0 kV and observe that little or no
signal remains in ESI mode. Then set the Corona parameter to 0 µA or
0 kV, and observe that little or no signal remains in APcI mode.
Result: The ESI probe is now optimized for ESCi mode.
Tip: If necessary, repeat the above procedure using the analyte of
interest, since ionization potentials may vary with different samples.
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