Monitor BTEX Compounds and Fuels in Water, Using Solid Phase Microextraction and Capillary GC

Significance of the Topic

Monitoring aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylenes (BTEX) and common fuels in water is vital for environmental safety and compliance with regulatory limits. Solid Phase Microextraction (SPME) coupled with capillary Gas Chromatography (GC) offers a solvent-free approach with enhanced sensitivity and rapid turnaround, making it practical for routine water quality screening and soil suspension analysis.

Objectives and Overview

The application note describes a streamlined protocol to extract and analyze BTEX compounds, kerosene, diesel fuel and gasoline in aqueous samples. The goals are to achieve reliable separation, low detection limits and total analysis time under 40 minutes per sample using a short, narrow-bore GC column and a polydimethylsiloxane SPME fiber.

Methodology and Instrumentation

Sample preparation relies on direct immersion of a 30μm polydimethylsiloxane-coated SPME fiber in a 4 mL water or soil suspension. Rapid stirring at ambient temperature for 15 minutes establishes equilibrium between the aqueous phase and polymer coating. Thermally desorbed analytes enter a capillary GC system for separation and detection.

Used Instrumentation

• SPME fiber: 30μm polydimethylsiloxane (Cat. 57308)
• SPME holder: manual sampling (Cat. 57330)
• GC column: SPB-1, 15 m × 0.20 mm ID, 0.20 μm film thickness (Cat. 24162)
• Carrier gas: helium at 30 cm/s flow rate
• Oven program: 40 °C (1 min) to 320 °C at 15 °C/min, hold 15 min
• Injector: splitless for 5 min, then split, at 250 °C
• Detector: flame ionization detector, 300 °C

Main Results and Discussion

Chromatograms demonstrate clear resolution of eight BTEX and fuel components across kerosene, diesel and gasoline spiked water samples at concentration levels ranging from 50 ppb to 4 ppm. Peak shapes remain symmetrical despite rapid extraction and short column length. Total cycle time per sample, including extraction and GC run, remains under 40 minutes, supporting high throughput.

Benefits and Practical Applications

• Solvent-free extraction reduces waste and improves detection limits relative to liquid-liquid extraction.
• Fast equilibration and analysis enable routine monitoring of groundwater, industrial effluents and contaminated sites.
• Compact instrumentation footprint suits mobile or field laboratory setups.

Future Trends and Potential Uses

Advances in fiber coatings and automated SPME autosamplers will further shorten extraction times and extend analyte range. Coupling SPME-GC with mass spectrometry will enhance selectivity for complex matrices. Integration into online monitoring systems may enable continuous water quality assessment.

Conclusion

The combination of SPME and short-column capillary GC provides a sensitive, rapid and solvent-free method for detecting BTEX and fuel contaminants in water. The approach meets environmental monitoring needs with minimal operator intervention and high sample throughput.

Reference

No literature references were provided in the source document.