MONITORING FOR PHARMACEUTICALS IN SURFACE WATER USING DIRECT AQUEOUS INJECTION ON THE AGILENT 6490 LC/QQQ

Significance of the Topic

The continuous release of pharmaceutical compounds and their metabolites into surface waters poses emerging risks to drinking water supplies and aquatic ecosystems. Trace levels of antibiotics, hormones, NSAIDs and other drug classes, often at sub-µg/L concentrations, have been reported worldwide, compelling regulatory bodies to consider monitoring and control measures.

Objectives and Study Overview

This work describes the development and validation of a direct aqueous injection method on an Agilent 6490 triple quadrupole LC/MS system. The aim was to quantify a broad panel of 30 pharmaceuticals in surface water without sample extraction, achieving low-ng/L detection limits and a dynamic range up to 250 ng/L.

Methodology and Instrumentation

A direct injection workflow was implemented in two ionization modes:

• Positive mode: 20 target compounds, 6 internal standards, 25 µL injection volume.
• Negative mode: 10 target compounds, 5 internal standards, 100 µL injection volume.

The system configuration included:

• Agilent 1200 Series HPLC with Autosampler G1329C, Micro Vacuum Degasser G1379B, 2-Position/6-Port Valve G4231A, Binary Pump G1312B, Column Compartment G1316A.
• Agilent 6490 QQQ Ion Funnel mass spectrometer.
• Zorbax Eclipse Plus C18 column (2.1 × 150 mm, 3.5 µm).

Main Results and Discussion

Method performance showed recoveries between 86.6 % and 120.6 % and limits of detection from 2 to 10 ng/L. Calibration was linear from 0 to 250 ng/L. In positive mode (23 min run), 12 of 20 compounds were detected in a river sample, totaling 431 ng/L. In negative mode (21 min run), 6 of 10 compounds were found, summing 197 ng/L. Chromatographic separation was robust across all targets.

Benefits and Practical Applications

This direct injection approach eliminates extraction steps, reducing analysis time, sample volume and variability. It enables high throughput monitoring of trace pharmaceuticals for environmental compliance, water quality assessment and contamination source tracking.

Future Trends and Potential Uses

• Extension to additional emerging contaminants and polar metabolites.
• Integration with automated sampling systems for real-time monitoring.
• Application to diverse water matrices (wastewater, groundwater, drinking water).
• Support for regulatory programs and risk assessment models.

Conclusion

The Agilent 6490 LC/QQQ direct injection method provides a sensitive, reproducible and streamlined workflow for multi-residue pharmaceutical analysis in surface waters. It meets low-ng/L detection requirements without laborious sample preparation, offering significant advantages for environmental monitoring.

Reference

• A.B.A. Boxall et al., Targeted monitoring for human pharmaceuticals in vulnerable source and final waters, DWI 70/2/231, Dec 2011.
• World Health Organization, Pharmaceuticals in drinking water, WHO/HSE/WSH/11.05, 2011.
• European Commission, Proposal amending Directives 2000/60/EC and 2008/105/EC on priority substances, COM(2011) 876 final, Jan 2012.