Dual Ion Source DUIS-2020 for Simultaneous ESI and APCI Measurement

Importance of the Topic

Analyzing a broad range of compounds in complex samples often requires multiple ionization techniques. Electrospray Ionization (ESI) excels for polar, high–molecular‐weight analytes, while Atmospheric Pressure Chemical Ionization (APCI) is better suited for less polar compounds. Traditionally, switching between these modes involves changing hardware and rerunning analyses, which slows laboratory throughput and extends method development time. A dual ion source capable of performing ESI and APCI simultaneously can streamline workflows, improve data consistency, and accelerate research and quality control in pharmaceuticals, environmental testing, and industrial analytics.

Study Objectives and Overview

The primary goal of this report is to introduce and evaluate the Dual Ion Source DUIS-2020 for the LCMS-2020 platform, enabling continuous, simultaneous ESI and APCI measurements. Key objectives include:

• Demonstrating seamless integration of both ionization modes without hardware exchange.
• Assessing performance in terms of sensitivity, peak shape, and data‐point acquisition under ultra‐fast chromatography conditions.
• Illustrating application to mixed samples of water-soluble and fat-soluble vitamins.

Methodology and Used Instrumentation

The DUIS-2020 combines a standard ESI probe with an APCI corona needle and secondary high-voltage power supply in a single interface. During analysis:

1. The liquid sample and mobile phase enter the integrated probe.
2. ESI nebulizes the liquid into fine droplets under a high‐voltage capillary.
3. Simultaneously, the corona needle generates APCI reagent ions for gas-phase reactions.
4. Ions from both modes pass through the desolvation line into the vacuum region of the LCMS-2020.

Polarity switching is achieved in 15 ms by serially arranging positive and negative high‐voltage supplies, preserving data density across narrow chromatographic peaks.

Main Results and Discussion

Using a mixture of thiamine and riboflavin (water-soluble) and calciferol (fat-soluble), individual ESI and APCI methods confirmed mode‐specific sensitivity: ESI detected water-soluble vitamins effectively, APCI favored calciferol. In dual-mode DUIS-2020 runs, all three vitamins were detected with balanced signal intensity in a single analysis. Chromatograms exhibited sharp peak shapes and consistent ion counts despite ultra‐fast LC gradients, demonstrating robust performance without compromise.

Benefits and Practical Applications

The DUIS-2020 enables:

• Higher sample throughput by eliminating probe changes and repeat injections.
• Rapid method development for unknown or diverse compound sets.
• Retention of standard ESI performance with added APCI capability.
• Effective polarity switching compatible with modern ultra‐fast LC methods.

This dual source is especially valuable in drug discovery, environmental screening, food safety, and industrial process monitoring.

Future Trends and Opportunities

Integration of dual ion sources with high‐resolution and hybrid mass analyzers could further expand analytical scope. Advances in software algorithms and AI‐driven method optimization may tailor ionization parameters in real time. Miniaturized dual sources and coupling with microfluidic LC systems are potential next steps toward portable, field‐deployable tandem ionization platforms.

Conclusion

The DUIS-2020 represents a significant advancement in LC-MS ion source design, merging ESI and APCI into a single, continuous workflow. It substantially reduces analysis time, maintains high sensitivity across analyte polarities, and supports ultra‐fast chromatography. This innovation enhances R&D and QC laboratories’ efficiency and paves the way for more versatile, high‐throughput mass spectrometry applications.