Mass Spectrometry Applications for Environmental Analysis

Importance of the topic

Rapid and accurate detection of trace environmental contaminants such as pesticides, herbicides and other organic pollutants in water, air and soil is critical for public health, environmental protection and regulatory compliance. Advances in mass spectrometry coupled with ambient ionization and online sample cleanup have greatly enhanced sensitivity, speed and throughput, enabling real-time monitoring and faster decision making in environmental and forensic applications.

Objectives and Overview

• To develop and evaluate direct analysis in real time (DART) with Orbitrap high-resolution MS for rapid pesticide identification in water.
• To implement online solid phase extraction (SPE) coupled to LC-MS/MS (TSQ Quantum Access MAX) for sub-ppt quantitation of herbicides, triazines, paraquat and diquat.
• To optimize fast HPLC gradients and column configurations for early eluting pesticides using divert valves and large injection volumes.
• To demonstrate method performance (linearity, accuracy, precision, detection limits) in compliance with EPA and EU standards.

Methodology and Instrumentation

• DART-SVP ambient ionization source with Exactive Orbitrap HRAM MS for direct screening of 23 pesticides in surface and drinking water using no sample prep and 30 s analysis per spot.
• Thermo Scientific TSQ Quantum Access MAX triple quadrupole MS with HESI source and Equan online SPE for LC-MS/MS analysis of herbicides and triazine compounds in 1–20 mL water injections.
• Chromatography systems: UltiMate 3000 x2 RSLC, Accela UHPLC and Surveyor pumps; divert valves for trap-and-backflush; Hypercarb, Hypersil GOLD C18, CLSHILIC and Acclaim Trinity P1/Q1 mixed-mode columns.
• Software: Xcalibur for Orbitrap data; ExactFinder and TraceFinder for unified targeted/non-targeted screening, quantitation, library search, qualifier ion ratios and automated reporting.

Main Results and Discussion

• DART-Orbitrap MS enabled rapid, high-confidence identification of 23 pesticides with mass accuracy <1 ppm and detection at ng/mL levels without preconcentration.
• Online SPE coupled to TSQ Quantum Access MAX achieved linear quantitation (R2>0.99) of 20 pesticides and triazines at 0.02–0.60 µg/L and 0.25–5.0 ng/L ranges, with MDLs of 0.09–0.10 µg/L for paraquat/diquat meeting EPA549.2 and EU98/83/EC limits.
• Fast HPLC gradients on Hypersil GOLD C18 reduced run times to <6 min for a mixture of early- and mid-eluting pesticides by using a trap column, divert valve and 5–8 µL injections in acetonitrile, maintaining good peak shape and S/N.
• Large-volume injections (up to 20 mL) using Equan and mixed-mode SPE cartridges provided 4- to 5-fold signal enhancement with repeatability ≤14% RSD, eliminating offline SPE.

Benefits and Practical Applications

• Substantial reduction in sample preparation time and solvent consumption by avoiding offline SPE and ion-pair reagents.
• High-throughput screening (HTP) with per-sample analysis times of seconds to minutes and automated data processing.
• Improved sensitivity and selectivity for trace contaminants in diverse water matrices (surface, drinking, waste), supporting rapid response to contamination events.
• Applicability in environmental quality control, food safety, forensic and clinical research, QA/QC and industrial analytics.

Future Trends and Possibilities

• Integration of ambient ionization techniques (e.g., DART, DESI) with high-resolution MS for in-field and near-real-time monitoring.
• Advances in automated online cleanup, micro-SPE and two-dimensional LC for broader multi-residue screening.
• Machine learning and AI-driven spectral interpretation, non-targeted screening and predictive analytics for unknown contaminant discovery.
• Development of portable, miniaturized MS systems for on-site environmental surveillance.
• Expansion of isotopic and fragmentation libraries to enhance confidence in identification and quantitation.

Conclusion

Combining ambient and online SPE ionization with high-resolution and triple quadrupole MS significantly streamlines environmental analysis by offering rapid, sensitive and selective detection of a wide range of pesticides, herbicides and toxins at trace levels. The described approaches meet stringent regulatory requirements, facilitate high-throughput workflows and pave the way for future innovations in real-time, on-site contaminant monitoring.

References

• Cody RB et al. Anal. Chem. 2005, 77, 2297; Gross J. Mass Spectrometry 2011.
• Beck JR et al. Thermo Fisher Sci. App. Note 51878 (2010); AN63413 (2016).
• Scheibner O. Thermo Fisher Sci. App. Note 64190 (2016).
• Kokkalis E. Thermo Fisher Sci. App. Note 572 (2016).
• EPA Method 536.0 (atrazine), EPA Method 549.2 (paraquat/diquat).