Automatic extraction and detection of PAHs in drinking water with SPDE-GC/MS

Significance of the Topic

Polyaromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants with recognized carcinogenic potential. Monitoring their levels in drinking water is critical to ensure compliance with stringent safety thresholds, typically below 0.005 µg/L (5 ppt).

Objectives and Study Overview

This study evaluates the performance of a fully automated solid-phase dynamic extraction coupled to gas chromatography/mass spectrometry (SPDE-GC/MS) for trace-level analysis of PAHs in spiked drinking water. The goal was to demonstrate sensitivity, reproducibility, and workflow integration suitable for routine water quality assessment.

Applied Methodology and Instrumentation

The analytical workflow integrates SPDE on a CTC CombiPAL autosampler with GC/MS detection. Key parameters:

• GC Conditions: Agilent 6890N with a 30 m × 0.25 mm × 0.25 µm VF-5MS column; oven program from 40 °C (3 min) at 10 °C/min to 320 °C (5 min); splitless injection at 250 °C with 30 mL/min purge; He carrier gas at 1.2 mL/min.
• MS Conditions: KODIAK 1500 EI source at 200 °C, 70 eV, 150 µA emission; mass scan range 40–400 amu at 600 ms/scan.
• SPDE Conditions: 10 mL sample in 20 mL headspace vial, extraction at 35 °C with 90 strokes of 1 mL each at 750 rpm, followed by thermal desorption (0.5 mL gas at 100 µL/s) and needle cleaning with heated water rinses.

Main Results and Discussion

The SPDE-GC/MS approach enabled detection and quantification of 13 EPA PAH congeners at 10 ppt levels in scan mode, with clear chromatographic resolution and reliable mass spectral identification. The enrichment cycle aligns with GC run time, supporting a continuous automated workflow. Sensitivity can be further enhanced by SIM or MS/MS modes.

Benefits and Practical Applications of the Method

The technique offers:

• High sensitivity in the low ppt range without offline extraction.
• Minimal sample volume (5–10 mL) and no organic solvents.
• Complete automation on standard autosampler hardware, saving bench space and labor.

This method is well-suited for routine drinking water monitoring and compliance testing.

Future Trends and Potential Applications

Advances may include integration of tandem mass spectrometry for enhanced selectivity, expansion to other semi-volatile contaminants, and miniaturized or multiplexed SPDE formats for high-throughput screening in environmental and industrial QA/QC.

Conclusion

The SPDE-GC/MS methodology provides a robust, sensitive, and fully automated solution for trace-level determination of PAHs in drinking water. Its alignment of extraction and analysis stages enables efficient, high-throughput monitoring in compliance with regulatory requirements.

Reference

• AQS-Ringversuch RV 2/04 - Trinkwasser PAK - TW O3 (9.2.2004)