A Rapid Solution for Screening and Quantitating Targeted and Non-Targeted Pesticides in Water using the Exactive Orbitrap LC/MS

Significance of the Topic

Rapid and comprehensive monitoring of pesticides in water is critical for ensuring environmental safety and regulatory compliance. The increasing number of analytes and tightening limits of quantitation demand efficient, high-throughput analytical solutions capable of detecting trace-level contaminants in various water matrices.

Objectives and Study Overview

The primary goal was to develop and validate a single-run workflow for targeted and non-targeted screening and quantitation of pesticides in surface, ground, and drinking water. This method combines online solid phase extraction with high-resolution accurate mass (HRAM) liquid chromatography–mass spectrometry and automated data processing to maximize throughput and identification confidence.

Methodology

Water samples were spiked with a mixture of twenty pesticides and metabolites covering a broad polarity range. Calibration curves were generated in ultrapure water over a range from 0.02 to 0.60 μg/L. Samples (1000 μL injection volume) underwent online SPE using two sequential columns (C18 and Hypercarb) to capture nonpolar and polar analytes, followed by backflush transfer to an analytical PFP column. Mass spectrometric analysis was performed in full-scan positive/negative switching mode at 50,000 resolution over a 20-minute run.

Instrumentation Used

• EQuan MAX automated online SPE-LC system
• Thermo Scientific Exactive Orbitrap mass spectrometer with HESI-II source
• Chromatographic columns: Hypersil GOLD C18, Hypercarb, Hypersil GOLD PFP
• ExactFinder software for unified qualitative and quantitative data processing

Main Results and Discussion

All twenty targeted analytes exhibited linear responses with no observable matrix interferences. The application of a 5 ppm mass window, retention time matching, and isotopic pattern confirmation provided high specificity. Non-targeted screening further identified additional compounds such as carbendazim and thiometoxam without extra analytical effort. Dual polarity acquisition ensured comprehensive ion detection without compromising sensitivity or mass accuracy.

Benefits and Practical Applications

This integrated workflow enables simultaneous qualitative and quantitative analysis in a single run, significantly reducing sample preparation time and resource requirements. Automated data processing streamlines reporting and enhances confidence in both targeted and non-targeted identifications, making the method suitable for routine environmental monitoring and regulatory compliance.

Future Trends and Opportunities

Advances in HRAM technology and data analytics will further expand the scope of non-targeted screening, allowing real-time identification of emerging contaminants. Integration with larger spectral libraries, machine learning algorithms, and cloud-based platforms is expected to improve throughput, reduce false positives, and support comprehensive environmental surveillance.

Conclusion

The presented method demonstrates a robust, high-throughput approach for screening and quantitation of a wide range of pesticides in water using online SPE coupled with Orbitrap LC–MS. The seamless combination of HRAM full-scan acquisition and automated data processing provides reliable identification and quantification of both known and unexpected analytes in a single workflow.

References

1. Zhang A, Chang J, Gu C, Sanders M. Non-targeted screening and accurate mass confirmation of 510 pesticides on the high resolution Exactive benchtop LC/MS Orbitrap mass spectrometer. Thermo Fisher Scientific Application Note 51878, 2010.
2. Beck J, Yang C. LC-MS/MS analysis of herbicides in drinking water at femtogram levels using 20 mL EQuan direct injection techniques. Thermo Fisher Scientific Application Note 437, 2008.