High Volume Injection up to 5 mL with the Agilent 1200 Infinity Series Online SPE Solution for Highest Sensitivity

Importance of the Topic

The analysis of trace contaminants such as pesticides in environmental and drinking waters demands highly sensitive injection techniques. Increasing injection volume enhances detectability of compounds at low nanogram-per-liter levels, improving monitoring efforts in water quality control, environmental research, and regulatory compliance.

Study Objectives and Overview

This technical overview evaluates the integration of a 5 mL sample loop upgrade with the Agilent 1200 Infinity Series Online SPE Solution. The aim is to assess precision, linearity, and operational flexibility when injecting large volumes (0.5–5 mL) for online solid phase extraction coupled to LC/MS analysis of pesticide residues.

Methodology and Instrumentation

Samples of tap water spiked with five pesticides at 50 ng/L (carbofuran, dimethoate, imazalil, metazachlor, metosulam) were processed in six replicates per injection volume. The workflow comprised three stages: sample loading onto SPE cartridges, gradient elution onto an analytical column, and cartridge reconditioning.

• Agilent 1200 Infinity Binary Pump and Online SPE direct injection kit
• Agilent 1290 Infinity Flexible Cube with two 2-position/10-port valves
• External valve drive (2-position/6-port) with 5 mL loop
• Agilent 1260 Infinity Standard Autosampler (900 µL head, multi-draw upgrade)
• Agilent 1290 Infinity Thermostat and ZORBAX Eclipse Plus C18 column
• Agilent 6460 Triple Quadrupole LC/MS with Jet Stream technology

Main Results and Discussion

Precision of peak areas (RSD) remained below 4 % for all compounds and injection volumes, with nonpolar matazachlor showing RSD < 2 %. Linearity (R²) ranged from 0.955 to 0.995 across pesticides. Peak area increased proportionally with volume up to ~4.5 mL, after which loop overfilling effects limited further gains due to parabolic flow profiles. Optimized autosampler programming and three-cycle flush of 15 mL transfer solvent ensured complete sample transfer and reproducible performance.

Benefits and Practical Applications

Implementing a high-volume injection loop extends detection capabilities into low ng/L ranges without compromising precision or linearity. The modular valve arrangement allows rapid switching between high-volume online SPE and standard direct injection, supporting diverse environmental and regulatory workflows in laboratories focused on trace analysis.

Future Trends and Opportunities

Further developments may include automated optimization of loop fill sequences, integration with high-throughput platforms, and adoption of novel sorbent materials to broaden compound coverage. Enhanced software control and real-time monitoring can improve reproducibility and facilitate method transfer across laboratories.

Conclusion

The Agilent 1200 Infinity Online SPE solution with a 5 mL high-volume injection upgrade delivers precise, linear performance for trace-level pesticide analysis. This approach enhances sensitivity and operational flexibility, making it well suited for stringent environmental and drinking water testing.

References

• Installation Note for Multidraw Upgrade Kit G131-68711, Agilent Technologies, 2006.
• López-Serna R, Pérez S, Ginebreda A, Petrovic M, Barceló D. Fully automated determination of 74 pharmaceuticals in environmental and waste waters by online SPE–LC–ESI–MS/MS. Talanta. 2010;83:410–424.
• Naegele E. Comparison of Direct Injection and Online SPE for Quantification by LC/MS of Trace-Level Herbicides in Water. Agilent Technologies Application Note 5991-2140EN; 2013.