Thermo Scientific μPAC Flex iON Connect ESI-MS interface

Significance of the topic

Low-flow liquid chromatography coupled to mass spectrometry demands minimal dead volume at the post-column junction to preserve chromatographic resolution and sensitivity. The µPAC Flex iON Connect interface addresses this critical need by simplifying and improving the reliability of nanoLC–ESI–MS connections.

Objectives and overview of the technical note

This technical note presents the design, installation procedure, and performance evaluation of the Thermo Scientific µPAC Flex iON Connect ESI-MS Interface. The goal is to reduce user interventions and post-column unswept volumes when coupling µPAC columns to Thermo Scientific Nanospray Flex ion sources.

Methodology and instrumentation

The interface comprises two precision-manufactured polyamide units: a docking part for permanent high-voltage and grounding connections, and a spray unit integrating two liquid junctions via conductive unions and fused-silica tubing. This configuration reduces required connections from four to two, minimizing dead volume.

Used instrumentation

• Thermo Scientific µPAC Flex iON Connect ESI-MS Interface (docking and spray units)
• Thermo Scientific 50 cm µPAC nanoLC columns
• Thermo Scientific Nanospray Flex Series ion source with DirectJunction adaptor
• High-resolution Thermo Scientific mass spectrometer

Main results and discussion

By optimizing emitter tip inner diameters (≤ 10 µm for 50–500 nL/min; 20–30 µm for 500–1500 nL/min) and spray voltages (1.7–2.5 kV), stable electrospray with improved peak symmetry and intensity was achieved. A 24-hour proteomics evaluation using a 50 cm µPAC column with HeLa digest and spiked retention time peptides demonstrated 7.15 % CV in peptide peak area, consistent protein identifications, and stable FWHM. Operator-skill testing across no-skill to expert levels showed negligible impact on chromatographic performance, confirming ease of use.

Benefits and practical applications

• Minimizes post-column dead volume for enhanced resolution and sensitivity
• Preassembled configuration reduces setup time and handling errors
• Compatible with standard nanoLC–ESI sources and a range of emitter tips
• Applicable to proteomics, metabolomics, and other low-flow LC–MS analyses

Future trends and potential applications

• Integration with automated and high-throughput nanoLC–MS platforms
• Extension to multiplexed or parallel low-flow systems
• Further miniaturization of interface components to push sensitivity limits

Conclusion

The µPAC Flex iON Connect ESI-MS Interface delivers a robust, low-dead-volume connection solution that enhances nanoLC–MS performance while simplifying installation and reducing dependency on operator skill.

References

1. Dolan JW, Upchurch P. Troubleshooting LC Fittings, Part I. LC-GC Magazine. 1988;6:788–790.
2. Stoll DR. Fittings and connections for liquid chromatography – so many choices. LCGC North America. 2018;36:304–311.
3. Thermo Fisher Scientific. Nanospray Flex Series Ion Source User Guide. Revision B.
4. PharmaFluidics. µPAC Flex iON Connect ESI-MS Interface Instructions for Use.
5. PharmaFluidics. Technical Note 5: Routine proteome analysis using 50 cm µPAC columns.