Performance Characteristics of the Agilent 1260 Infinity II Hybrid Multisampler

Importance of the Topic

The choice of injection mode in high-performance liquid chromatography (HPLC) autosamplers critically impacts data quality, analysis speed and sample throughput. Innovations in injection design can minimize delay volumes, reduce carryover of challenging analytes and maintain retention time stability across varying flow conditions. The Agilent 1260 Infinity II Hybrid Multisampler offers two distinct injection modes—traditional flow-through injection and the novel Feed Injection—allowing laboratories to tailor performance for demanding quantitative applications.

Objectives and Study Overview

This study systematically evaluates the performance characteristics of the Agilent 1260 Infinity II Hybrid Multisampler in both flow-through and Feed Injection modes. Key metrics include peak area precision, injection linearity, retention time repeatability and carryover. The goal is to demonstrate how each mode supports reliable quantitation over a broad injection volume range and under fast gradient conditions.

Methodology and Instrumentation

The evaluation employed an Agilent 1260 Infinity II LC system configured with both injection modes via a specialized built-in valve. A single set of analytical conditions was applied to assess performance comparability. Software control was provided by Agilent OpenLab CDS 2.7.

Used Instrumentation

• Agilent 1260 Infinity II Hybrid Multisampler (G7167C)
• Agilent 1290 Infinity II High-Speed Pump (G7120A)
• Agilent 1290 Infinity II Multicolumn Thermostat (G7116B)
• Agilent 1290 Infinity II Diode Array Detector with Max-Light Cartridge Cell (G4212-60007/60008)
• Columns: ZORBAX RR StableBond C18 (3.0×100 mm, 3.5 µm) and Pursuit XRs C18 (2.0×50 mm, 3 µm)

Main Results and Discussion

• Peak Area Precision: In Feed Injection mode, relative standard deviations (RSD) ranged from 3.7–2.3% at nL volumes and fell below 0.15% RSD for volumes ≥2 µL. Flow-through injection delivered comparable precision across 0.1–100 µL.
• Linearity: Both modes exhibited exceptional linearity over the full injection volume range, with correlation coefficients (R²) ≥0.99999.
• Retention Time Repeatability: Using a four-component isocratic standard, retention time RSDs remained under 0.01% at feed speeds of 20% and 80% of pump flow, confirming stable chromatography under variable injection dynamics.
• Carryover: Flow-through injection produced carryover between 1–3 ppm for chlorhexidine, while Feed Injection yielded 4–8 ppm, both values indicating minimal sample-to-sample contamination.

Benefits and Practical Applications

The hybrid multisampler combines the simplicity of flow-through injection with the low delay volumes and feed diluent mediation of Feed Injection. Laboratories can exploit low-volume precision for trace analysis, high-volume linearity for preparative screening and robust carryover control for sticky analytes. The system supports both fast gradient methods and routine isocratic assays in pharmaceutical, food safety and environmental testing.

Future Trends and Potential Applications

Continued advancement may include further miniaturization of injection loops, integration of AI-driven method optimization addressing diluent effects in real time, and broader adoption of feed-injection approaches in ultra-high-pressure LC and LC-MS workflows. Enhanced automation and adaptive flow control will further reduce cycle times and improve reproducibility for high-throughput screening.

Conclusion

The Agilent 1260 Infinity II Hybrid Multisampler delivers highly precise, linear and low-carryover performance in both flow-through and Feed Injection modes. Its flexibility and stability under varied operating conditions make it a powerful tool for quantitative HPLC applications across industrial and research laboratories.

References

• Agilent Technologies. Technical Overview: Performance Characteristics of the Agilent 1260 Infinity II Hybrid Multisampler, April 2023.