Robust LC-MS analysis of pesticides with 1.0 mm i.d. column using the Vanquish Horizon UHPLC system

Significance of the topic

The accurate measurement of pesticide residues in food is essential for consumer safety and regulatory compliance. High sensitivity and reduced solvent use are key challenges in trace-level analysis, driving the adoption of microflow UHPLC coupled to MS/MS. The application of 1.0 mm i.d. columns offers enhanced detection limits and sustainability benefits.

Objectives and Overview

This application note evaluates the Thermo Scientific Vanquish Horizon UHPLC system with 1.0 mm i.d. columns for the quantification of over 250 pesticides at ppb and sub-ppb levels in food matrices. It compares performance to traditional 2.1 mm columns and examines system robustness at low flow rates.

Methodology and Instrumentation

Sample preparation involved QuEChERS extraction of strawberry and leek with acetonitrile, followed by centrifugation and matrix-matched calibration to 1–10 µg/L. Chromatographic methods employed gradient elution using 1.0 mm and 2.1 mm columns at flow rates from 0.1 to 0.45 mL/min. Extra-column volume was minimized with 50 µm i.d. capillaries and specialized low-flow needle inserts.

Used Instrumentation

• Vanquish Horizon UHPLC (System Base, Binary Pump H, Split Sampler HT, Column Compartment H)
• TSQ Endura triple quadrupole MS with Ion Max NG ESI source
• Vanquish MS connection kit and nanoViper capillaries

Main Results and Discussion

Theoretical sensitivity gain from 2.1 mm to 1.0 mm columns is 4.4-fold; observed increase was approximately twofold for 98 pesticides in strawberry matrix. Limits of detection (S/N>3) were achieved at 0.25 ppb for most analytes. Calibration linearity showed R²>0.95 for 85% of compounds. Precision studies yielded area RSD<25% at 0.5 ppb and retention time SD<0.01 min. Peak widths (FWHM) were under 2 s. At 100 µL/min flow, retention time RSD remained below 0.1% and area RSD around 1%. Robustness testing over 200 injections demonstrated area RSD<2.5%.

Benefits and Practical Applications

• Sub-ppb detection for regulatory compliance
• Reduced solvent consumption by approximately fourfold
• High-throughput separations with narrow peaks
• Reliable quantitation in complex food matrices

Future Trends and Possibilities

Further miniaturization and integration with high-resolution mass spectrometry are expected to drive lower detection limits and broader screening capabilities. Advances in automated sample preparation, greener solvents, and novel ionization sources will enhance sustainability and throughput in pesticide residue analysis.

Conclusion

The Vanquish Horizon UHPLC system with 1.0 mm i.d. columns and optimized fluidic paths delivers robust, sensitive, and efficient pesticide quantification. It outperforms conventional 2.1 mm methods in sensitivity and environmental footprint while maintaining precision and system stability for routine trace analysis.

References

• Uclés Moreno A.; Herrera López S.; Reichert B.; Lozano Fernández A.; Hernando Guil M.D.; Fernández-Alba A.R. Anal. Chem. 2015, 87, 1018–1025.
• Ledigo-Quigley C.; Smith N.W.; Mallet D. J. Chromatogr. A 2002, 976, 11–18.
• Boychenko A.; Meding S.; Samonig M.; Swart R. Thermo Fisher Scientific Poster Note PN-64787-EN-0616S, 2016.
• Greco G.; Martins C.P.B.; Bousova K.; Swart R. Thermo Fisher Scientific Application Note 1138, AN-71729-EN-0815S, 2015.