Getting Started with UltraPerformance Convergence Chromatography

Importance of the Topic

UltraPerformance Convergence Chromatography (UPC2) merges supercritical fluid and liquid chromatography principles to achieve high efficiency, orthogonal selectivity and reduced solvent consumption. Its normal-phase-like separations with reversed-phase ease-of-use make UPC2 valuable for complex mixtures in pharmaceuticals, environmental analysis and industrial QA/QC.

Objectives and Overview

This guide presents a structured approach to adopt UPC2 in the chromatographic laboratory. It covers the definition of UPC2, method development strategies, key considerations for system setup, and its role as a greener, higher-throughput alternative to normal-phase liquid chromatography.

Methodology and Used Instrumentation

UPC2 uses liquid carbon dioxide as a weak eluent and an organic co-solvent modifier as a strong eluent. Method development typically involves:

• Screening stationary phases (BEH, BEH 2-EP, CSH Fluoro-Phenyl, HSS C18 SB)
• Optimizing co-solvent type, concentration and gradient profile
• Evaluating mobile phase additives (acids, bases) to improve peak shape and selectivity
• Adjusting pressure (ABPR) and column temperature to fine-tune retention
• Selecting an appropriate sample diluent to balance solubility and chromatographic performance

Key instrumentation components include the Waters ACQUITY UPC2 System with binary solvent manager, convergence manager, column compartment, and compatible detectors such as PDA, ELSD or MS.

Main Results and Discussion

Case studies illustrate significant performance gains of UPC2 over traditional NPLC:

• Anthralin assay transferred from a 10-min NPLC method to a 6-min UPC2 method, reducing cost per run by over 95% and meeting USP criteria without sample rework
• Tolbutamide analysis time cut from 20 to 2 minutes by using a 3.0×100 mm UPC2 column with 1.7 µm particles
• Estradiol impurity profiling achieved improved sensitivity (detecting additional low-level impurities) and cut solvent costs from $5.89 to $0.05 per analysis

Studies on co-solvent strength, additive concentration, pressure and temperature confirm their predictable impact on retention, selectivity and peak shape, enabling rapid method optimization.

Benefits and Practical Applications

• Up to tenfold faster separations and reduced cycle time
• Lower organic solvent consumption and waste generation
• Gradient capability and reproducible retention for complex mixtures
• Compatibility with mass spectrometry and other detectors
• Broad analyte solubility range (Log P between –2 and 9)
• Direct replacement of NPLC methods with minimal method adaptation

Future Trends and Applications

Emerging directions for UPC2 include chiral separations with novel stationary phases, on-line coupling with high-resolution mass spectrometry, expanded lipidomic and natural product analyses, and further miniaturization for micro-flow applications. Advances in green chemistry will continue to reduce carbon footprint and solvent use in industrial and regulatory environments.

Conclusion

UPC2 stands out as a powerful, green, cost-effective chromatographic platform. Its blend of supercritical fluid selectivity with UPLC robustness supports a wide range of analytical challenges, from pharmaceutical impurities to environmental and industrial assays. Adopting UPC2 can streamline workflows, improve data quality and align with sustainable laboratory practices.

References

• Giddings JC. A critical evaluation of the theory of gas chromatography. In Gas Chromatography, 1964, A. Goldup (ed.), Elsevier; 1965:3–24.
• Waters Corporation. ACQUITY UPC2 System Guide; 2013.
• Waters Corporation. ACQUITY UPC2 Columns Care & Use Manual; 2013.