Fast and highly sensitive analysis of multiple drugs in ground-, surface- and wastewater

Importance of the Topic

The presence of unmetabolized pharmaceuticals from human and veterinary use in ground, surface and wastewater poses significant environmental and health concerns. Sensitive and rapid methods for detecting these trace contaminants are essential for monitoring pollution, assessing ecological risk and ensuring water quality.

Goals and Overview of the Study

This work aimed to develop a streamlined, high-throughput LC-MS/MS workflow for simultaneous quantification of multiple drug classes at trace levels in complex water matrices. Key objectives included eliminating labor-intensive sample preparation, minimizing analysis time and achieving sub-nanogram per milliliter detection limits.

Methodology and Instrumentation

The study employed online solid-phase extraction (SPE) coupled directly to a rapid LC separation and triple quadrupole mass spectrometer. Method development leveraged:

• A quaternary low-pressure gradient eluent (LPGE) system with integrated solvent blending to optimize SPE loading and elution conditions without manual solvent mixing.
• Automated multiple-reaction monitoring (MRM) optimization via six sequential flow-injection steps to refine precursor selection, quadrupole biases and collision energies.
• A single analytical column (Kinetex C8, 2.6 μm, 100 × 2.1 mm) for sub-6-minute chromatographic runs.

Used Instrumentation

• Shimadzu LCMS-8050 triple quadrupole mass spectrometer with ESI interface and 5 ms polarity switching.
• Two binary pumps each equipped with LPGE units for SPE solvent blending and analytical gradient delivery.
• Online SPE column (Strata-X, 25 μm, 20 × 2 mm) and autosampler.

Main Results and Discussion

The final method enabled direct analysis of nine representative drugs—including antibiotics, analgesics, lipid-lowering agents and radio-opaque compounds—over a calibration range of 0.05 to 2 ng/mL. Key performance features:

• Limit of quantification at 0.05 ng/mL for all analytes.
• Total run time of 6 minutes per injection.
• High reproducibility and peak capacity despite polarity switching and diverse chemical properties.

Benefits and Practical Applications

This approach offers:

• High sensitivity suitable for environmental monitoring of trace pharmaceuticals.
• Fully automated sample processing reducing hands-on time and potential variability.
• Rapid throughput for large-scale surveillance or screening programs.

Future Trends and Opportunities

Prospective developments may include expanding compound panels, integrating high-resolution MS for non-target screening, coupling with data-driven workflows for real-time pollution assessment and deploying portable LC-MS platforms for on-site analyses.

Conclusion

The presented online SPE LC-MS/MS method demonstrates a robust, fast and highly sensitive solution for multi-class drug quantification in water. Its automation, low detection limits and minimal sample preparation make it well suited for routine environmental monitoring and research applications.