PAHs, chlorinated hydrocarbons, pesticides - Large volume injection of surface water extract

Significance of the topic

This application note addresses the need for sensitive and comprehensive trace analysis of priority pollutants such as polycyclic aromatic hydrocarbons (PAHs), chlorinated hydrocarbons and pesticides in surface water. Monitoring these compounds at low microgram-per-liter levels is critical for assessing water quality and protecting environmental and public health.

Objectives and Study Overview

The aim of the study was to develop a streamlined workflow combining minimal sample preparation with large volume injection (LVI) in gas chromatography–mass spectrometry (GC–MS) to achieve reliable quantification of over eighty target analytes in surface water extracts. The approach focuses on maximizing analyte recovery and instrument sensitivity while reducing analysis time.

Methodology and Instrumentation

Samples were spiked with salts and internal standards, then subjected to simple in-vial extraction using a pentane/ether mixture without phase separation. Following brief mixing, 200–250 µL of the organic supernatant was automatically injected at 6 µL/s via a large volume on-column injector. GC separation was performed on an Agilent CP-Sil 24 CB-MS fused silica WCOT column (30 m×0.25 mm, 0.25 µm film) equipped with a large volume guard and pre-column. The temperature program ranged from 40 °C to 320 °C under helium flow (2.5 mL/min). The MS detector operated in full-scan mode at 310 °C.

Main Results and Discussion

The method enabled simultaneous detection and quantification of 88 compounds spanning aromatics (e.g., benzene, toluene, xylenes), chlorinated solvents and phenols, polychlorinated biphenyls (PCBs), organochlorine pesticides (e.g., HCH isomers, DDT and metabolites), and PAHs (e.g., naphthalene, phenanthrene, benzo(a)pyrene). Calibration in the range 1–50 µg/L showed good linearity, sensitivity and reproducibility. Baseline separation of critical isomers and low detection limits demonstrate the robustness of the LVI-GC-MS approach.

Benefits and Practical Applications

• Minimal sample preparation reduces handling errors and solvent consumption
• Large volume injection improves sensitivity without the need for pre-concentration steps
• Broad analyte coverage meets regulatory requirements for water quality monitoring
• Automated injection enhances throughput and reproducibility

Future Trends and Potential Applications

Advances may include integration of high-resolution MS for increased selectivity, automated online extraction systems for continuous monitoring, miniaturized systems for field analysis, and extension to emerging contaminants such as pharmaceuticals and per-and polyfluoroalkyl substances (PFAS).

Conclusion

The presented LVI-GC-MS workflow provides a powerful tool for environmental laboratories to perform rapid, sensitive, and comprehensive screening of trace organic pollutants in surface water, combining simplicity of sample preparation with high analytical performance.

Reference

Agilent Technologies, Application Note A01500, 2011.