Initial work on Automating Dispersive Liquid Liquid Micro Extraction for EPA 8270

Importance of the Topic

Environmental monitoring of organic pollutants is critical for public health, regulatory compliance and ecosystem protection. The EPA Method 8270 protocol covers over 70 hazardous analytes in solid, liquid and gaseous matrices. Streamlining sample preparation for high-throughput laboratories can deliver faster turnaround times, reduced solvent usage and improved safety.

Objectives and Study Overview

This study evaluates the automation of Dispersive Liquid–Liquid Microextraction (DLLME) for EPA 8270 targets. The goal is to integrate automated mixing, emulsification and centrifugation into a single workflow to extract polycyclic aromatic hydrocarbons, pesticides and PCBs from aqueous samples with minimal solvent volumes and operator intervention.

Instrumentation

• GERSTEL Dual Head MultiPurpose Sampler (MPS) xt
• GERSTEL mVORX vortexer option
• Anatune CF-200 Centrifuge
• Anatune high-recovery 9.5 mL vials
• Agilent 7890B Gas Chromatograph
• Agilent 5977B GC/MSD with High Efficiency Source

Methodology

Propan-2-ol (8 mL) was added to 32 mL deionised water; 6 mL aliquots were dispensed into high-recovery vials. The automated sequence on the GERSTEL MPS delivered 300 µL dichloromethane (with pentane), forming an emulsion. Samples were vortexed at 2 000 rpm for 2 minutes, then centrifuged at 4 500 rpm for 1 minute. The denser organic layer (~50 µL) was directly injected (1 µL splitless) onto a DB-5 MS column, using a 40 °C to 350 °C thermal gradient.

Key Results and Discussion

Calibration standards (0.05, 0.25, 0.5 and 1.00 µg/L) of ~70 analytes exhibited excellent linearity (r² > 0.997). Extracted ion chromatograms for representative compounds (naphthalene, trifluralin, heptachlorobenzene, triallate) at 0.05 µg/L confirmed low detection limits. Automation enabled reproducible emulsification and phase separation, matching or exceeding manual DLLME performance while reducing analyst workload.

Benefits and Practical Applications

• Miniaturisation: smaller sample bottles, reduced transport/storage requirements.
• Solvent savings: only 300 µL dichloromethane per extraction reduces costs and hazards.
• Automation: hands-free sample prep frees analysts for higher-value tasks.
• Throughput: just-in-time preparation aligns extraction with GC injection, cutting turnaround.

Future Trends and Potential Applications

Further studies will explore diverse water matrices and complex environmental samples. Integration with other microextraction techniques and on-line coupling to GC/MS systems could advance automated workflows in forensic, food safety and pharmaceutical analysis. Ongoing instrument advances may enable fully remote or field-deployable microextraction units.

Conclusion

Automated DLLME for EPA 8270 analytes delivers robust extraction efficiency, excellent linearity and low detection limits while drastically reducing solvent consumption and manual labor. This workflow enhances laboratory productivity and safety, establishing a scalable approach for high-throughput environmental monitoring.

References

• USEPA Method 8270: Semivolatile Organic Compounds by GC/MS
• Quick J., Carrier D., Dunscombe J., Stubbs J. Technical Note AS186, Anatune Ltd. 2017