Benefits of KNAUER´s trouble-free analytical capillaries in terms of HPLC and UHPLC system performance

Importance of the topic

High‐performance liquid chromatography (HPLC) and ultra high‐performance liquid chromatography (UHPLC) rely on consistent fluidic connections. Capillaries and fittings, though small and inexpensive, can significantly affect band spreading, dwell volume, and overall system performance. Improving these consumables enhances reproducibility, reduces setup errors, and boosts laboratory efficiency.

Study objectives and overview

This whitepaper assessed KNAUER’s new trouble‐free MarvelXACT™ capillaries and fittings versus traditional K-Connect ferrule‐based assemblies on AZURA® Analytical HPLC (862 bar) and UHPLC (1240 bar) systems. Key aims included:

• Evaluating ease of use and reusability
• Measuring changes in extra‐column and dwell volumes
• Comparing chromatographic performance under isocratic and gradient conditions

Methodology and instrumentation

Both systems were assembled per manufacturer instructions, swapping only the capillaries/fittings. A standard column and sample (butyl and pentyl benzoate) were used for:

• Isocratic runs to determine retention times, peak width, and theoretical plates
• Gradient runs to measure dwell volume impact

Used instrumentation

• HPLC 862 bar: AZURA P 6.1L pump, AS 6.1L autosampler, Eurospher II C18 150×4 mm column, DAD detector, MarvelXACT™ and K-Connect capillary start-up kits
• UHPLC 1240 bar: AZURA P 8.1L pump, AS 6.1L autosampler, Zorbax RRHD 1.8 µm C18 50×2 mm column, DAD detector, MarvelXACT™ and K-Connect capillary start-up kits

Main results and discussion

• HPLC 862 bar: Switching to MarvelXACT™ raised system backpressure from 60 bar to 70 bar but yielded retention times, peak heights, and plate counts nearly identical to K-Connect, thanks to a slightly higher dwell volume paired with a reduced extra‐column volume.
• UHPLC 1240 bar: The trouble‐free capillaries halved extra‐column volume (from ~8.6 µL to ~3.8 µL), boosting theoretical plates from ~56 000 to ~83 000. Retention times shifted marginally due to lower post‐column volume, while dwell volumes increased modestly.

Benefits and practical applications

• Tool‐free assembly with patented torque‐limiting click‐feedback to prevent under- or over-tightening
• Reusability for over 100 connection cycles
• Stable, reproducible fluidic interfaces independent of user experience
• Performance equal to or exceeding conventional fittings, especially in low‐void‐volume UHPLC setups

Future trends and potential uses

As chromatography moves toward higher pressures and miniaturized formats, low‐volume, hassle‐free connections will be critical. Future developments may include narrower inner diameters, integrated microfluidic manifolds, and single‐use disposable cartridges for rapid method changes and enhanced system robustness.

Conclusion

KNAUER’s MarvelXACT™ trouble‐free analytical capillaries deliver user‐friendly installation, high reusability, and consistent performance. They match or improve chromatographic results on AZURA® HPLC and UHPLC platforms and represent a straightforward upgrade from conventional ferrule systems.

References

No external references were provided in the source document.