Utilization of GCxGC-TOFMS as a Broad-Spectrum Analysis for Endocrine-Disrupting Compounds in Urban and Rural Watersheds

Importance of the Topic

The presence of endocrine-disrupting compounds (EDCs) in natural waters is of growing global concern due to their potential to interfere with hormonal systems, leading to reproductive, developmental, and immune disorders in wildlife and humans.

The development of sensitive, reliable analytical methods is critical for environmental monitoring, risk assessment, and regulatory compliance.

Objectives and Study Overview

This application study aimed to establish a broad-spectrum analytical workflow for targeted and untargeted EDC detection in urban and rural watersheds.

Key goals:

• Develop a solid-phase extraction (SPE) protocol compatible with diverse EDC classes.
• Optimize comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GCxGC-TOFMS) for high-resolution separation and rapid full-scan acquisition.
• Apply a reference standard library to identify and quantify EDCs, pharmaceuticals, personal care products, and industrial by-products in watershed samples.

Methodology

Water samples (1 L) were acidified to pH 2 and extracted using 500 mg Supel-Select HLB cartridges via vacuum SPE. Cartridges were conditioned with water/methanol and acetone, loaded slowly, dried under vacuum, and eluted with acetone/methanol and dichloromethane. Extracts were concentrated in a SpeedVac and reconstituted in acetone prior to analysis.

Data processing employed ChromaTOF software with a user-defined reference library. A composite reference of 152 EDCs and related compounds was applied to classify peaks as “Match,” “Out of Tolerance,” or “Not Found.”

Applied Instrumentation

• Agilent 7890 gas chromatograph equipped with LECO dual-stage quad-jet thermal modulator.
• GERSTEL MPS2 auto-sampler for 1 µL splitless injections.
• Primary column: Rxi-5Sil MS (30 m×0.25 mm i.d.×0.25 µm film).
• Secondary column: Rxi-17Sil MS (1.0 m×0.18 mm i.d.×0.18 µm film).
• Helium carrier gas at 1.5 mL/min.
• LECO Pegasus 4D TOFMS operating at 200 spectra/s over m/z 35–800 with 230 °C source temperature.

Main Results and Discussion

A total of 13 duplicate one-liter samples from six watershed sites yielded 102 distinct chemicals.

Highlights:

• Detected classes included EDCs, personal care products, pharmaceuticals, pesticides, polymer additives, flame retardants, and PAHs.
• 81% of compounds were found in at least five analyses, indicating widespread distribution.
• Calibration for 1,4-dichlorobenzene and 1-methylnaphthalene showed excellent linearity (r>0.999).
• Comprehensive GCxGC contour plots facilitated resolution of coeluting isomers and low-level analytes.

Benefits and Practical Applications

This workflow provides a robust platform for environmental laboratories to monitor a broad range of trace contaminants in surface and groundwater.

Applications include:

• Routine water quality assessment and pollution source tracking.
• Regulatory compliance monitoring for emerging contaminants.
• Support for ecological risk assessments and remediation strategies.

Future Trends and Potential Uses

Advancements likely to enhance EDC monitoring include:

• Expansion of spectral libraries and in-silico prediction tools to cover new emerging compounds.
• Integration of automated SPE and online coupling with GCxGC-TOFMS for higher throughput.
• Real-time data mining with machine learning to detect unknown contaminants.
• Miniaturized sampling devices for in-field screening and rapid response.

Conclusion

The combined SPE and GCxGC-TOFMS approach demonstrates high sensitivity, resolution, and reliability for comprehensive analysis of EDCs and related pollutants in watersheds. The use of a reference-based processing strategy enhances targeted and untargeted compound identification, supporting effective environmental monitoring and risk management.