GCxGC-TOFMS Utilized as a Broad-Spectrum Analysis for Endocrine Disruptor Compounds in Urban and Rural Watersheds

Significance of the Topic

Endocrine-disrupting compounds (EDCs) pose significant risks to aquatic ecosystems and human health due to their ability to interfere with hormonal function at trace concentrations. Widespread use of pharmaceuticals, pesticides, industrial additives and consumer-product ingredients leads to persistent contamination of both urban and rural watersheds. Reliable, broad-spectrum analytical methods are essential for assessing environmental exposure, supporting regulatory compliance and guiding remediation strategies.

Objectives and Study Overview

This study aimed to develop and validate a comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC-TOFMS) method for simultaneous targeted and untargeted detection of a wide range of EDCs in surface water samples. Water from six rural and urban Midwestern US point sources was collected, extracted by solid-phase extraction (SPE), and analyzed to demonstrate method robustness, sensitivity and reproducibility.

Methodology and Instrumentation

Sample Preparation and SPE:

• Adjust 1 L water samples to pH 2 and load on 500 mg Supel™ Select HLB cartridges via vacuum manifold.
• Condition cartridges with water/methanol and acetone, dry under vacuum, elute with acetone/methanol and dichloromethane.
• Concentrate eluate to dryness, reconstitute in acetone and inject 1 µL.

GC×GC-TOFMS Configuration:

• Agilent 7890 GC with LECO dual-stage quad-jet thermal modulator and GERSTEL MPS2 autosampler.
• Primary column: 30 m×0.25 mm ID×0.25 µm Rxi-5SilMS; Secondary column: 1.0 m×0.18 mm ID×0.18 µm Rxi-17SilMS.
• Carrier gas: Helium at 1.5 mL/min; splitless injection at 250 °C.
• Temperature programs: Primary 75 °C → 300 °C (6 °C/min), Secondary 80 °C → 305 °C (6 °C/min); modulator offset +20 °C; transfer line 280 °C.
• LECO Pegasus 4D TOFMS: mass range 35–800 u, source 230 °C, detector 1700 V, acquisition 200 spectra/s.

Data Processing:

• Build a 152-component reference in ChromaTOF® software for targeted and untargeted screening.
• Match library spectra (NIST 08) with ≥60 % similarity; apply True Signal Deconvolution®.
• Quantitation via six-point calibration (50 ppb–25 ppm) for selected analytes, achieving r² > 0.999.

Main Results and Discussion

Analysis of thirteen 1 L water samples from six point sources yielded 102 distinct chemical detections, representing pharmaceuticals, pesticides, plasticizers, flame retardants, industrial by-products and polycyclic aromatic hydrocarbons. Eighty-one percent of these compounds were observed in at least five of the 26 GC×GC runs, indicating consistent recovery and detection. Two-dimensional separation resolved coeluting isomers and complex mixtures, while TOFMS provided high mass-spectral match scores and rapid full-scan acquisition, enabling detection at low nanogram levels.

Benefits and Practical Applications

Key advantages of the developed GC×GC-TOFMS method include:

• High peak capacity and chromatographic resolution for complex environmental matrices.
• Comprehensive screening for both known and emerging EDCs without extensive method reconfiguration.
• Rapid, reproducible quantitation for routine monitoring and regulatory compliance.
• Data-mining capability via reference-based processing for retrospective analysis of untargeted compounds.

Applications span environmental monitoring programs, water-quality assessment, industrial discharge surveillance and academic research on contaminant fate and transport.

Future Trends and Opportunities

Advances in GC×GC instrumentation and data analysis will further enhance screening capabilities:

• Integration with high-resolution mass spectrometry for accurate mass and structural elucidation of unknowns.
• Development of on-site or field-deployable systems for real-time water quality monitoring.
• Machine-learning driven data processing to predict toxicity profiles and prioritize emerging contaminants.
• Expansion of spectral libraries for broader coverage of novel industrial chemicals and transformation products.

Conclusion

This study demonstrates that comprehensive two-dimensional GC×GC coupled with TOFMS, combined with optimized SPE extraction and reference-based data processing, provides a robust, sensitive and versatile platform for the broad-spectrum detection of endocrine disruptors and other pollutants in complex water matrices. The method’s high resolution and rapid acquisition facilitate both targeted quantitation and untargeted screening, offering an effective tool for environmental chemists and water-quality professionals.

Reference

• Susan D. Richardson, “Water Analysis: Emerging Contaminants and Current Issues”, Analytical Chemistry, 2007, 79, 4295–4324.
• Michael Ebitson, “Determining Pharmaceuticals and Personal Care Products in Water by Automated Solid Phase Extraction”, Horizon Technology, Inc., AN061-101101.
• Rebecca A. Trenholm et al., “Broad Range Analysis of Endocrine Disruptors in Pharmaceuticals Using Gas Chromatography and Liquid Chromatography Tandem Mass Spectrometry”, Chemosphere, 65 (2006) 1990–1998.