Alternative Procedure for Extraction and Analysis of PAHs in Seafood by QuEChERS-SBSE-GC-MS

Significance of the Topic

The analysis of polycyclic aromatic hydrocarbons (PAHs) in seafood is critical for food safety following oil spill incidents such as Deepwater Horizon. Rapid, sensitive and cost-effective methods are essential to protect public health, comply with regulatory limits, and support fisheries management.

Objectives and Study Overview

This work aims to evaluate a combined QuEChERS solvent extraction and Stir Bar Sorptive Extraction (SBSE) approach for trace-level PAH determination in seafood tissue. The goal is to achieve regulatory detection limits, maintain high precision and accuracy, and enable high sample throughput.

Methodology

• Sample Preparation: Homogenize 3 g of seafood tissue in water.
• QuEChERS Extraction: Add acetonitrile, 6 g MgSO4 and 1.5 g sodium acetate; shake and centrifuge to partition PAHs into the organic phase.
• SBSE Cleanup and Concentration: Combine 1 mL acetonitrile extract with 4 mL 0.1 M NaHCO3 and a GERSTEL Twister stir bar; agitate to adsorb PAHs, removing polar interferences.
• Thermal Desorption and GC–MS Analysis: Transfer the Twister to a Thermal Desorption Unit and analyze by GC–MS using a programmable temperature vaporization inlet under specified temperature programs.

Instrumental Setup

• Gas Chromatograph: Agilent 7890 with programmable temperature vaporization inlet.
• Mass Spectrometer: Agilent 5975C inert XL MSD with triple-axis detector.
• Thermal Desorption Unit and MPS2 Autosampler (GERSTEL).
• Column: Restek Rxi-5Sil MS, 30 m × 0.25 mm × 0.25 μm, helium carrier gas.

Results and Discussion

• Linearity: Excellent response from 1 to 250 ng/g in matrix-matched extracts.
• Recovery: Mean recoveries of 107% ± 5% RSD at spiking levels of 2.5 and 25 ng/g in fish tissue.
• Matrix Cleanup: Using bicarbonate in SBSE significantly reduces background interferences compared to water-based extraction.
• Detection Limits: Single-digit ppb detection achieved; further improvements possible via dual-bar desorption or splitless transfer.
• Sample Throughput: Estimated 40–60 samples per analyst per instrument per day.
• Method Transferability: Validation across multiple laboratories and standard reference material analysis showed good agreement with certified values.

Benefits and Practical Applications

This integrated QuEChERS–SBSE–GC–MS workflow offers rapid sample processing, improved cleanup, high sensitivity and compliance with regulatory requirements. It is suitable for routine monitoring of PAHs in diverse seafood matrices, supporting environmental response and food safety programs.

Future Trends and Potential Applications

• Automation and multiplexed SBSE to further increase throughput.
• Combination with high-resolution mass spectrometry for enhanced selectivity.
• Extension to other environmental and biological matrices.
• Miniaturized and in-field sampling devices for on-site screening.

Conclusion

The QuEChERS–SBSE–GC–MS method demonstrates robust performance for trace PAH analysis in seafood. It meets regulatory detection limits, ensures accurate quantitation, and delivers high throughput, making it a valuable tool in environmental and food safety laboratories.