Source tuning on the OptiFlow pro ion source
The OptiFlow pro ion source is the fourth generation of source in the Turbo V ion source family. Fundamental to this family of sources is the orthogonal spray design with V heater configuration, which focuses heat in the optimal spot to achieve high sensitivity through high desolvation from the ESI droplets. The Optiflow pro source is an all-in-one versatile ion source with interchangeable towers/probes, enabling users to easily switch between different ionizations and different flow rate regimes. Probe and electrode positions are pre-optimized for maximal performance with no user intervention needed.
With the newest source design there are some optimization behaviors that a user switching from older generation sources should consider. Subtle changes in the source geometry, and in the probe/electrode configuration, as well as the addition of E Lens technology, all contribute to different optimal source conditions than in the previous generation of sources.
Analytical flow tuning - ESI
Both the ionization spray voltage (ISV) and the nebulizing gas (GS1) will optimize to lower values than the IonDrive Turbo V ion source, so it is recommended that users do a quick re-optimization of these two settings when migrating methods over to the SCIEX Triple Quad 7500 system – QTRAP ready. The heater gas (GS2) has been found to be fairly flat so minimal tuning is required. A setting of 70 for Gas2 works for most experiments.
As an example, the optimization profiles comparing the OptiFlow Pro ion source to the IonDrive Turbo V ion source at 500 µL/min flow rates are shown below for a mixture of small molecule drugs.
From this optimization effort, we developed some recommended starting points:
- At 500 µL/min – use a TEM of 600, a Gas1 of 35, a Gas2 of 70, and an ISV of 1500 V
Analytical flow tuning - APCI
Fewer tuning differences were observed when comparing the two sources in APCI mode. The nebulizer current was found to optimize at lower settings (0.5 – 3 µA on OptiFlow Pro Source as compared to 2-4 µA on the IonDrive source). Also, the Gas1 did tune a little bit lower on the OptiFlow Pro Source because of the lower required current.
Recommended starting points:
- For small molecules at 500 µL/min – use a TEM of 400, a Gas1 of 30, and a NC 2 µA
Microflow tuning - ESI
Similar optimization experiments were performed at microflow rates, comparing potential tuning differences between the OptiFlow Pro Source (with and without the E Lens Technology) and the OptiFlow® Turbo V Source. As expected, the source tuning was relatively similar between the two sources when the E Lens was not installed. Addition of the E Lens Technology did impact tuning of the OptiFlow Pro Source, requiring a higher GS1 setting to achieve the higher source temperatures (ISV was not impacted).
Recommended starting points (use CUR of 40 and Gas 2 of 70 for all):
- For small molecules at 3 µL/min – use a TEM of 150, a Gas1 of 20, and a ISV of 4500 V
- For small molecules at 30 µL/min – use a TEM of 350, a Gas1 of 45, and a ISV of 4500 V
- For small molecules at 100 µL/min – use a TEM of 450, a Gas1 of 45, and a ISV of 4500 V
- For peptides at 5 µL/min – use a TEM of 200, a Gas1 of 40, and a ISV of 3750 V