Determination of PCBs in Large-Volume Fish Tissue Samples Using Accelerated Solvent Extraction (ASE)

Significance of the topic

Monitoring polychlorinated biphenyls in fish tissue is essential for assessing bioaccumulation of priority organic pollutants and ensuring food safety. Traditional extraction methods are time consuming and solvent intensive, driving the need for rapid, automated approaches.

Objectives and study overview

This study demonstrates the application of accelerated solvent extraction to quantify PCBs in large 30 g fish tissue samples. Key goals include achieving high recovery, reducing lipid coextraction, and streamlining sample preparation for GC/ECD analysis.

Methodology and instrumentation

Sample preparation and extraction were optimized to process cod fillet tissue spiked with nine PCB congeners. Fish tissue was mixed with diatomaceous earth, loaded into a 100 mL ASE cell containing basic alumina and a cellulose filter for selective cleanup. Extraction conditions were:

• Solvent: methylene chloride
• Temperature 125 °C, pressure 1500 psi
• Heatup 5 min, static 3 min per cycle, three cycles
• Flush volume 60%, purge 120 s
• Solvent use 120–140 mL per sample

Post extraction, extracts were dried over sodium sulfate, concentrated under nitrogen to 10 mL, and analyzed by GC/ECD using a 30 m × 0.32 mm column with temperature programming from 100 to 300 °C at 15 °C per minute.

Key results and discussion

Selective ASE provided an average recovery of 96.9% for nine PCB congeners with 6.1% RSD (n=5). Incorporating 10 g of alumina retained approximately 75 mg of lipid per gram, yielding cleaner extracts. Comparative chromatograms showed that selective extraction eliminated extensive post-extraction cleanup required by nonselective methods. Total extraction time was 18 minutes per sample, significantly faster than Soxhlet or sonication.

Benefits and practical applications of the method

This ASE approach offers rapid, reproducible extraction of PCBs from large sample masses with minimal solvent use. The selective cleanup step within the cell reduces laboratory workload by removing lipids inline, supporting high-throughput monitoring in environmental and food safety laboratories.

Used instrumentation

• ASE 300 accelerated solvent extractor with 100 mL cells
• Gas chromatograph with electron capture detector

References

1. Dionex Corporation. Selective Extraction of PCBs from Fish Tissue. Application Note 327, Sunnyvale CA.
2. Schantz M, Nichols J, Wise S. Evaluation of Pressurized Fluid Extraction for the Extraction of Environmental Matrix Reference Materials. Anal Chem. 1997;69:4210–4219.
3. Ezzell J, Richter B, Francis E. Selective Extraction of PCBs from Fish Tissue Using Accelerated Solvent Extraction. Amer Environ Lab. December 1996;12–13.
4. U.S. EPA. Test Methods for Evaluating Solid Waste Method 3545. SW-846 Update III. Fed Regist. 1997;62(114):32451.

Future trends and potential applications

Further miniaturization and integration of cleanup sorbents will enhance selectivity and reduce solvent consumption. Coupling ASE with high-resolution mass spectrometry may extend monitoring to emerging contaminants in diverse biological matrices.

Conclusion

Accelerated solvent extraction provides a fast, efficient, and selective method for determining PCBs in large fish tissue samples. Inline cleanup reduces sample preparation time and resource requirements, making ASE a valuable tool for environmental and food safety analysis.