Determination of Pesticides in Fruits and Vegetables Automated with FREESTYLE QuEChERS and LC-MS/MS

Importance of the Topic

QuEChERS has become the standard for pesticide analysis in fruits and vegetables due to its simplicity and wide applicability. However, manual clean-up steps contribute to variability and matrix-related ion suppression in LC-MS/MS. Automating the clean-up step with a non-dispersive approach improves sample throughput, extract purity, and analytical precision in routine pesticide monitoring labs.

Objectives and Study Overview

This study presents the automated clean-up of fruit and vegetable samples using the FREESTYLE QuEChERS system coupled directly to LC-MS/MS. The goals were to evaluate clean-up efficiency, matrix suppression reduction, and quantitative performance for 219 pesticides in apple, bell pepper, and lettuce matrices.

Methodology and Instrumentation

Samples (10 g) were extracted with acetonitrile and QuEChERS salts, followed by centrifugation. The supernatant was subjected to automated non-dispersive SPE clean-up on the FREESTYLE platform and directly injected into an Agilent Infinity II 1290 LC system with an API 5500 triple quadrupole MS in positive ESI MRM mode. Chromatography used a NUCLEOSHELL Bluebird RP18 column with a 5–100% methanol gradient in 5 minutes, 0.7 mL/min flow, 30 °C, and 20 µL injection of 2 ng/mL standard.

Used Instrumentation

• FREESTYLE BASIC robotic platform with SPE module and Direct Injection interface
• Agilent 1290 Infinity II HPLC (modules G7116B, G7167B, G7120A)
• Sciex API 5500 triple quadrupole MS with TurboSpray ESI
• NUCLEOSHELL Bluebird RP18 column, 2.7 µm, 50 × 4.6 mm

Main Results and Discussion

Gravimetric and UV-Vis analysis (200–800 nm) demonstrated over 90% removal of matrix components after automated clean-up, leading to reduced ion suppression. LC-MS/MS quantification of 219 pesticides yielded 89–92% of analytes within 60–120% recovery across all matrices. Deviations outside this range were attributed to specific matrix effects, which can be corrected by matrix-specific factors. Reproducibility was high, with RSDs generally below 20%.

Benefits and Practical Applications

• High-throughput, unattended operation (up to 120 samples/day)
• Non-dispersive clean-up yields cleaner extracts and lower matrix suppression
• Improved precision and reduced sample-to-sample variability
• Seamless integration with existing LC-MS/MS workflows

Future Trends and Applications

Automated non-dispersive QuEChERS can expand to additional matrices and analyte classes. Advances may include tailored sorbent chemistries, miniaturized cartridges, and AI-driven method optimization. Integration with multiplexed detection systems and on-line sample preparation will further enhance laboratory efficiency and data quality.

Conclusion

The FREESTYLE QuEChERS automation delivers robust, reproducible pesticide analysis in fruits and vegetables, achieving high recoveries and significantly reducing matrix effects. Its 24/7 operation supports routine laboratories with greater throughput and consistency compared to manual clean-up methods.

References

• No additional literature references provided.