Analysis of Trace Level Pesticides in Fruits and Vegetable by GC/MS/MS Using Agilent Ultra Inert Liners with Wool

Significance of the Topic

Trace-level pesticide monitoring in fruits and vegetables is critical for food safety and regulatory compliance. Ultratrace detection ensures consumer protection by verifying that residues remain below health-based maximum residue limits. High-throughput analytical platforms must deliver robust sensitivity, reproducibility and minimal maintenance across diverse matrices.

Objectives and Study Overview

This work evaluates the performance of Agilent Ultra Inert splitless liners packed with glass wool for GC/MS/MS analysis of 33 pesticides in fruit and vegetable extracts. Key goals included:

• Assessing liner inertness and signal stability across hot splitless (HSL), cold splitless (CSL) and large volume injection (LVI) modes
• Establishing limits of quantitation (LOQs) in real matrices down to 1 ng/mL
• Comparing reproducibility and peak shape in complex extracts (orange, pepper, spinach, strawberry, pear, flower)

Methodology and Instrumentation

Sample Preparation:

• QuEChERS AOAC extraction of fruits and vegetables
• Post-spike with multi-point calibration standards (1–100 ng/mL)

GC/MS/MS Conditions:

• Agilent 7890A GC coupled to 7000 Triple Quadrupole MS, Agilent 7693 autosampler with MMI inlet
• Ultra Inert single-taper splitless liner with glass wool (p/n 5190-2293)
• HP-5MS UI column (15 m × 0.25 mm, 0.25 µm film)
• Injection modes evaluated: HSL (1 µL), CSL (1 µL), LVI (5 µL)
• Oven program: 75 °C hold, ramp to 150 °C at 50 °C/min, then to 200 °C at 6 °C/min, final to 300 °C at 16 °C/min
• MRM data acquisition, transfer line/source/quads at 300 °C

Main Results and Discussion

Ultra Inert liners with wool delivered:

• Excellent inertness: negligible active pesticide adsorption, stable peak shapes across injections
• High repeatability: %RSD ≤ 10% for 10 ng/mL pesticides in matrix blanks under HSL, CSL and LVI
• Improved sensitivity: LVI achieved LOQs of 1 ng/mL in pepper, orange and spinach extracts, with calibration R2 > 0.995
• Matrix protection: glass wool trapped non-volatiles, extending column and ion source lifetime

Comparative evaluation showed LVI increased on-column load without compromising reproducibility, though more frequent liner replacement is advised for heavily loaded matrices.

Benefits and Practical Applications

Use of Ultra Inert liners with wool supports:

• Robust trace-level pesticide quantitation in diverse produce
• Flexible method development across injection modes to balance sensitivity and throughput
• Reduced downtime by safeguarding analytical columns and MS sources

Future Trends and Potential Applications

Advances may include automated online QuEChERS-GC/MS/MS workflows, further miniaturization of injection volumes and novel liner coatings to push LOQs below 1 ng/mL. Integration with high-resolution MS and data-driven matrix effect correction could enhance multi-residue screening.

Conclusion

Agilent Ultra Inert splitless liners packed with wool deliver superior inertness, reproducibility and sensitivity for GC/MS/MS pesticide analysis in complex fruit and vegetable matrices. LVI methods extend detection limits to 1 ng/mL, while robust liner performance reduces maintenance, making them ideal for routine food safety and regulatory testing.

Reference

Limian Zhao and Kai Meng, Agilent Technologies, Poster P-75, FPRW 2011