AB Sciex 4500 Series System User's Manual page 115

2. Look through the glass window to make sure that the needle is aligned with the tip
facing the orifice.
Adjust the APCI Probe Position
Make sure that the curtain plate orifice remains clear of solvent or solvent drops at all times. The
position of the probe relative to the curtain plate orifice affects sensitivity and signal stability. The
probe vertical (Y-axis) position is dependent on flow rate. For low flow rates, move the probe to
its lowest position. For higher flow rates, move the probe above the curtain plate orifice.
1. In Tune and Calibrate mode, double-click Manual Tune.
2. Run the method to optimize the ion source.
3. Look through the window of the ion source housing to view the position of the probe.
4. Set the X-axis adjustment knob to 5 and the Y-axis adjustment knob to 5.
5. Use FIA to inject the sample or use a Tee connection with a syringe to infuse the
sample at a high flow rate.
6. Monitor the signal in the Analyst software.
7. Use the X-axis adjustment knob to adjust the probe in small increments until the best
signal or signal-to-noise ratio is achieved.
Tip!
column injections.
8. Use the Y-axis adjustment knob to adjust the probe in small increments until the best
signal or signal-to-noise ratio is achieved.
The APCI probe optimizes toward the orifice plate. After the probe is optimized, it
needs only minor adjustment.
Optimize the Nebulizer Current
The ion source is controlled by current and not by voltage. Select the appropriate current for the
acquisition method, regardless of ion source selection position. Use the PEEK adjustment knob
to position the corona discharge needle so that the tip of the needle points right at the center of
the probe.
• Start with a Nebulizer Current (NC) value of 1 and increase until the best signal or
signal-to-noise ratio is achieved.
The NC (Nebulizer Current) applied to the corona discharge needle usually
optimizes between 1 µA and 5 µA in positive mode. If there are no changes in signal
when increasing the current, then leave the current at the lowest value that provides
the best signal or signal-to-noise ratio.
System User Guide
Document Number: D5030863 A
It is easier to optimize signal and signal-to-noise with FIA or on-
Turbo V™ Ion Source User Reference
4500 Series of Instruments
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