AUTOMATED ONLINE SPE/TANDEM MS ANALYSIS OF TRACE ORGANIC CONTAMINANTS IN DRINKING WATER - Agilent Ultivo Triple Quadrupole LC/MS System

Importance of the Topic

Drinking water can contain trace organic contaminants originating from pesticides, pharmaceuticals, personal care products, and industrial chemicals. Although individual compounds are present at very low concentrations, long-term exposure to mixtures of these substances may pose health risks that require careful monitoring.

The development of automated, sensitive analytical methods is critical for routine surveillance of potable water supplies and for supporting environmental regulatory frameworks.

Objectives and Study Overview

This work presents an automated method combining online solid-phase extraction (SPE) on the Agilent 1290 Infinity Flexible Cube with subsequent analysis by the Agilent Ultivo Triple Quadrupole LC/MS. Thirty-one representative trace organic contaminants (TOrCs) were quantified in spiked drinking water samples over a range of 0.5–200 ng/L. Key goals were to achieve low detection limits, high sample throughput, and robust quantitation with minimal manual intervention.

Methodology and Instrumentation

A dual-cartridge online SPE configuration on the Agilent 1290 Infinity Flexible Cube enabled injection volumes up to 900 µL. While one cartridge loaded and concentrated analytes from a 750 µL sample, the second cartridge was eluted, supporting continuous operation and increased throughput.

After a 4-minute enrichment phase, the valve switched to elution mode, delivering analytes directly into a reversed-phase HPLC gradient on a ZORBAX RRHD Eclipse Plus C18 column (3.0 × 50 mm, 1.8 µm). Detection employed dynamic multiple reaction monitoring (dMRM) on the Ultivo triple quadrupole MS.

Instrumentation details:

• Online SPE cartridge: ZORBAX Extend C18, 4.6 × 12.5 mm, 5 µm
• SPE solvents: water with 0.1% formic acid (load), 1:1 acetonitrile/isopropanol (elute)
• HPLC mobile phases: water/0.2 mM NH4F and acetonitrile/0.2 mM NH4F
• MS source conditions: drying gas 11 L/min (250 °C), sheath gas 12 L/min (375 °C), capillary voltage ±4 kV, nozzle voltage ±500 V, dynamic MRM acquisition

Key Findings and Discussion

• Linearity: All 31 analytes exhibited calibration curves with R² > 0.99 over 0.5–200 ng/L.
• Detection limits: 19 compounds had limits of detection below 0.5 ng/L, 10 compounds between 0.5 and 5 ng/L, and 2 slightly above 5 ng/L using only 750 µL sample volumes.
• Retention time stability: Over 54 consecutive injections, selected analytes showed retention time deviations under 0.01 minutes and consistent peak shapes.
• Throughput: A total cycle time of 16 minutes per sample (4 minutes enrichment, 8.5 minutes gradient, 2.5 minutes post-run) was achieved.

Benefits and Practical Applications

• Fully automated workflow reduces manual steps and potential sample contamination.
• High sensitivity and broad dynamic range support regulatory compliance and environmental monitoring programs.
• Compact instrumentation footprint suits laboratory environments with limited space.

Future Trends and Potential Applications

Emerging developments in microflow SPE and miniaturized LC/MS systems are expected to further reduce sample and solvent consumption. Integration with high-resolution mass spectrometry may allow non-target screening and comprehensive profiling of emerging contaminants. Real-time monitoring platforms could leverage online SPE–LC/MS workflows for continuous water quality assessment.

Conclusion

The combination of the Agilent 1290 Infinity Flexible Cube online SPE and the Ultivo Triple Quadrupole LC/MS provides a robust, sensitive, and high-throughput solution for trace organic contaminant analysis in drinking water. With low detection limits, excellent reproducibility, and an automated process, this method is well suited for environmental laboratories and quality control applications.

Reference

1. C. G. Daughton, T. A. Terhes. Pharmaceuticals and personal care products in the environment: agents of subtle change. Environmental Health Perspectives 107, 907–938 (1999).
2. T. Anumol, S. Snyder. Rapid analysis of trace organic compounds in water by automated online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry. Talanta 132, 77–86 (2015).