Optimizing System Dispersion on the Agilent 1290 Infinity II LC

Significance of the Topic

In high-performance liquid chromatography, system dispersion determines the sharpness of chromatographic peaks and thus directly affects resolution, peak capacity, and overall efficiency. Minimizing dispersion is especially critical for ultrafast UHPLC analyses on sub-2 µm particles and narrow-bore columns, where even small band-broadening volumes can degrade performance.

Objectives and Study Overview

This study evaluates the performance of the Agilent 1290 Infinity II LC fitted with the Ultralow Dispersion Kit. Key goals include:

• Comparing band broadening and theoretical plate count versus a standard 1290 Infinity II configuration with 0.12 mm capillaries
• Benchmarking against a competing UHPLC system optimized for low dispersion
• Assessing both isocratic separations on short, narrow-bore columns and gradient elutions of an anesthetic mixture

Methodology and Instrumentation

All experiments were conducted on an Agilent 1290 Infinity II LC with the following modules:

• High-speed Pump (G7120A)
• Multisampler with modified needle seat (G7167B)
• Multicolumn Thermostat with heat-exchanger (G7116B)
• Diode Array Detector, 10 mm Max-Light standard cell (G7117B)
• Ultralow Dispersion Kit including 0.075 mm ID capillaries, 0.6 µL Max-Light Cartridge Cell (G4212-60038), Quick-Turn fittings, and dispersion-optimized flow path (p/n 5067-5963)

Chromatographic conditions:

• Isocratic tests with a 10 cm × 50 µm PEEKsil transfer line using caffeine
• Isocratic standard on 2.1 × 50 mm, 1.7 µm C18 column at 1.5 mL/min
• Gradient of six anesthetics on 2.1 × 50 mm, 1.7 µm C18 column (0–95 % organic in 1 min)

Main Results and Discussion

Isocratic separation on short columns demonstrated that the Ultralow Dispersion Kit reduced system dispersion at half-height from 6.5 µL to 3 µL, and at 5σ from 16 µL to 7 µL. Early-eluting peaks achieved up to a 141 % increase in theoretical plate count. For gradient elution of anesthetics, peak capacity improved by 19–72 % compared to a competing UHPLC system, confirming superior efficiency for rapid separations.

Benefits and Practical Applications

The Ultralow Dispersion Kit offers:

• Enhanced resolution and peak capacity for ultrafast isocratic and gradient methods
• Reduced analysis times with sharper peaks and higher throughput
• Compatibility with existing 1290 Infinity II modules for broad HPLC and UHPLC applications

Future Trends and Possibilities

Advances may include further miniaturization of flow paths, integration of dispersion-optimized cells for complex multidimensional separations, and application of these designs to high-throughput screening, proteomics, and metabolomics workflows.

Conclusion

The Agilent 1290 Infinity II LC with Ultralow Dispersion Kit significantly minimizes system dispersion, leading to higher theoretical plate counts and peak capacities. It surpasses both standard 1290 Infinity II configurations and a leading competitor in ultrafast isocratic and gradient UHPLC analyses.

References

1. Agilent A-Line UHPLC Fittings Technical Overview, Agilent Technologies, 2015, publication 5991-5525EN.
2. Schneider S. Application Note: Agilent 1290 Infinity LC Ultralow Dispersion Kit, Agilent Technologies, 2012, publication 5991-0826EN.
3. Comparative Poster, 38th Symposium of HPLC, 2011.