DETERMINATION OF THE HYDROCARBON-INDEX DIN EN ISO 9377-2:2000

Significance of the Topic

The accurate determination of the hydrocarbon oil index in water is critical for environmental monitoring, regulatory compliance and safeguarding drinking, surface and wastewater. The EN ISO 9377-2:2000 method provides a standardized approach for quantifying total petroleum hydrocarbons down to 0.1 mg/L. Automating sample cleanup and concentration accelerates throughput, minimizes user error and ensures consistent recovery rates across diverse water matrices.

Objectives and Study Overview

This application note demonstrates the fully automated adaptation of EN ISO 9377-2:2000 using LCTech’s FREESTYLE SPE and EVAporation modules. The goal is to integrate solid phase extraction with on-line evaporation, validate recovery and retention capacities, and evaluate method precision and linearity for regulatory-compliant hydrocarbon analysis.

Methodology and Instrumentation

The procedure involves four main steps:

• Extraction of hydrocarbons from water samples into petroleum ether.
• Clean-up on ready-to-use Elufix Florisil columns via SPE.
• Concentration of eluates to a defined final volume using EVAporation.
• Analysis by GC-FID with external calibration standards.

The method can run as separate SPE and EVAporation sequences or as a combined "FLEX method" where eluate flows directly into the evaporation chamber. Key operational parameters include sample loading at 10 mL/min, controlled nitrogen drying, washing with petroleum ether, and vacuum-driven evaporation to 1 mL at 300 mbar.

Main Results and Discussion

Recovery tests without on-line evaporation yielded 96 % recovery versus a certificate value of 98.8 %. Retention capacity for stearyl stearate was confirmed at 0.01, in agreement with specifications. The standalone EVAporation yielded > 90 % recovery across 0.2–2.0 mg/mL standards. The combined SPE/EVAporation workflow produced recoveries above 90 % with relative standard deviations of 3–4 %. Calibration curves showed excellent linearity (R²=1) and reproducible chromatographic profiles for repeated injections.

Benefits and Practical Application

• Fully automated workflow reduces hands-on time and risk of contamination.
• High recoveries and low RSDs ensure reliable quantification.
• Flexible method configuration supports manual or automated clean-up and concentration.
• Suitable for routine monitoring of drinking water, surface water, groundwater and wastewater.

Future Trends and Potential Applications

Advances may include coupling automated SPE/EVAporation with GC-MS for enhanced compound identification, miniaturized cartridges for lower solvent consumption, real-time online monitoring systems and extension to complex matrices such as soil pore water or industrial effluents.

Conclusion

The automated implementation of EN ISO 9377-2:2000 on FREESTYLE SPE and EVAporation platforms delivers fast, robust and reproducible quantification of total petroleum hydrocarbons in water samples. Its high throughput and consistent performance facilitate regulatory compliance and support large-scale environmental and quality control laboratories.

Instrumentation

• FREESTYLE SPE module for automated sample loading and clean-up
• FREESTYLE EVAporation module for precise evaporation to final volume
• Elufix Florisil ready-to-use SPE columns
• Specialized racks, adapters and 60 mL/GC vials for sample handling
• Gas chromatograph with FID detector for quantitation