Use the Plot Chromatogram tool to evaluate the stability of the spray.

Before you evaluate the spray stability, verify that the syringe contains the appropriate calibration solution and the ion source parameters pane displays the appropriate settings. Also, make sure that the calibration solution has warmed to room temperature, which takes about 30 minutes after you remove it from refrigeration.

Parameter

Setting

Syringe pump settings box

2 to 5 μL/min flow rate and a syringe volume that matches the size of the syringe installed on the syringe pump

Ion polarity mode

Positive or Negative

Data type

Profile

Procedure

  1. Select the Define Scan tab. Then, in the Define Scan pane, set the following parameters:
  2. Scan Type: SIM (Q1)
  3. Precursor (m/z): 622 (602 in Negative mode)
  4. Source Fragmentation (V):
  5. – TSQ Series II MS (excluding the TSQ Fortis Plus and TSQ Fortis): 30 V (Positive mode), 30 V (Negative mode)
  6. – TSQ Fortis Plus and TSQ Fortis: 20 V (Positive mode), 30 V (Negative mode)
  7. Scan parameters for a TSQ Series II MS in positive mode (excluding the TSQ Fortis Plus and TSQ Fortis)
    Scan parameters for a TSQ Series II MS in positive mode (excluding the TSQ Fortis Plus and TSQ Fortis)
  8. Scan parameters for a TSQ Fortis Plus and TSQ Fortis in positive mode
    Scan parameters for a TSQ Fortis Plus and TSQ Fortis in positive mode
  9. Scan parameters for a TSQ Fortis Plus and TSQ Fortis in negative mode
    Scan parameters for a TSQ Fortis Plus and TSQ Fortis in negative mode
  10. Select System On to place the MS in On mode.
  12. The MS begins to scan and applies high voltage to the spray insert. A real-time mass spectrum appears in the Tune window.
  13. Real-time mass spectrum in the spectrum view
    Real-time mass spectrum in the spectrum view
  14. Select Plot Chromatogram at the lower right of the Tune window.
  15. The Plot Chromatogram dialog box opens.
  16. In the Plot Chromatogram dialog box, do the following:
  17. In the mass table, type 622 in the Mass column of row 1.
  18. Plot Chromatogram dialog box with a user defined m/z value
    Plot Chromatogram dialog box with a user defined m/z value
  19. Select OK.
  20. The Spray Stability check begins
  21. You can observe the signal stability and the effects of changes to various parameters in the chromatogram and spectrum plots. You can also observe a real-time graph of the RSD for a 10 Da-selected ion monitoring (SIM) scan that is centered around the masses that you defined in the Plot Chromatogram dialog box.
  22. When the check finishes, the %RSD plot displays the calculated results.
  23. Observe the RSD graph, and review the signal stability rating and %RSD value.
  24. The following table lists the criteria for a stable spray in either positive or negative ion polarity mode.
  26. Spray Stability check results
    Spray Stability check results
  27. If the signal stability rating is poor or the %RSD value is above the threshold, optimize the API source parameters as follows.
  28. Ensure the proper installation of the sweep cone.
  29. Make slight adjustments to the forward/backward position of the API probe.
  30. Change the API depth position from L/M to M.
  31. Optimize the spray voltage, starting with 3.5 kV and increasing or decreasing to achieve the maximum stable signal.
  32. The spray voltage must not exceed 3.6 kV.
  33. Adjust the sheath gas:
  34. – For the positive mode, set the sheath gas to 0 or 4.
  35. – For the negative mode, adjust the sheath gas plus or minus 1 unit. The optimal value for the negative mode can vary from 0 to 5, but it is usually either 0 or between 4 and 5.
  36. Adjust the flow rate. For example, if you started at 5 μL/min, lower the flow rate by 1 μL/min. If you started at 3 μL/min, increase the flow rate by 1 μL/min..
  37. Once the spray stability is achieved, select Full Scan mode to start the system check or the system calibration.