Determination of 19 Polycyclic Aromatic Hydrocarbon Compounds in Salmon and Beef

Significance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are persistent, potentially carcinogenic compounds that accumulate in fatty foods such as fish and meat. Regulatory agencies including the U.S. FDA and the European Commission mandate monitoring of PAH residues at low parts-per-billion levels to ensure consumer safety. Analytical challenges arise from both efficient extraction of PAHs from lipid-rich matrices and removal of co-extracted fats prior to instrumental analysis.

Study Objectives and Overview

This study aimed to develop and validate a multiresidue method for the determination of 19 PAH compounds in salmon and beef. The method integrates a two-step solid–liquid extraction (SoLE) with ethyl acetate/acetonitrile, followed by selective lipid cleanup using Agilent Captiva EMR—Lipid cartridges, and final analysis by GC/MS/MS in dynamic MRM mode. Performance was evaluated in terms of recovery, precision, linearity, limits of quantification (LOQs), and matrix cleanup efficiency.

Methodology

Sample Preparation:

• Homogenize 2.5 g of salmon or beef; spike with standards and internal standards.
• Perform two sequential SoLE steps using 5 mL of 20:80 ethyl acetate/acetonitrile, each shaken for 10 min and centrifuged.
• Combine extracts and adjust with water before loading onto a Captiva EMR—Lipid cartridge for gravity elution.
• Apply a second elution with 0.625 mL of 16:64:20 ethyl acetate/acetonitrile/water to improve heavy PAH recoveries.
• Conduct back-extraction with isooctane to remove water and exchange into a GC-compatible solvent.

Used Instrumentation

• Agilent 7890B gas chromatograph with electronic pneumatic control and multimode inlet.
• Agilent 7000D triple quadrupole mass spectrometer operated in Dynamic MRM mode.
• Agilent 7693A automatic liquid sampler and backflush system with Ultimate union.
• Laboratory equipment: centrifuge, test tube shaker, Geno/Grinder homogenizer, positive pressure manifold.

Main Results and Discussion

The optimized method achieved the following performance:

• Recoveries for all 19 PAHs ranged from 50 % to 120 % across low (1 ng/g), mid (10 ng/g), and high (100 ng/g) spiking levels, with RSDs below 20 %.
• Calibration curves from 1 to 500 ng/g showed linearity with R2 greater than 0.99.
• Critical heavy PAHs (benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, chrysene) were quantifiable at LOQ of 1 ng/g, meeting EU criteria of 0.9 ng/g.
• Matrix removal efficiency measured by gravimetric residue: 60 % in salmon and 92 % in beef after EMR—Lipid cleanup.

Benefits and Practical Applications

• The two-step SoLE improves extraction of both light and heavy PAHs from high-fat matrices.
• Captiva EMR—Lipid cartridges selectively retain co-extracted lipids, simplifying sample cleanup and reducing solvent use.
• Isooctane back-extraction enables efficient removal of residual water and seamless transfer to GC-amenable solvent.
• The method complies with regulatory requirements for seafood and meat quality control laboratories.

Future Trends and Potential Applications

• Further lowering the LOQ and LOD for critical PAHs by optimizing sample size or instrument sensitivity.
• Extension of the workflow to other high-fat food matrices such as dairy products and processed oils.
• Integration with high-resolution mass spectrometry for expanded screening of emerging contaminants.
• Automation of sample preparation to increase throughput in routine testing laboratories.

Conclusion

The developed method combining two-step solid–liquid extraction, Captiva EMR—Lipid cleanup, and GC/MS/MS analysis offers a robust, precise, and sensitive approach for quantifying 19 PAHs in salmon and beef. It delivers regulatory compliance, excellent matrix removal, and reliable performance across a broad concentration range.

Reference

1. U.S. Food and Drug Administration. Protocol for Interpretation and Use of Sensory Testing and Analytical Chemistry Results for Re-Opening Oil-Impacted Areas Closed to Seafood Harvesting Due to the Deepwater Horizon Oil Spill, 2010.
2. European Commission Regulation (EC) 836/2011, Official Journal of the European Union, 2011, 215, 9.
3. Takigami H.; et al. Brominated flame retardants and other polyhalogenated compounds in indoor air and dust from two houses in Japan. Chemosphere 2009, 76, 270–277.
4. Viegas O.; et al. A comparison of the extraction procedures and quantification methods for the chromatographic determination of PAHs in charcoal grilled meat and fish. Talanta 2012, 88, 677–683.
5. Stapleton H. M.; et al. Determination of polybrominated diphenyl ethers in environmental standard reference materials. Anal. Bioanal. Chem. 2007, 387, 2365–2379.
6. Forsberg N. D.; Wilson G. R.; Anderson K. A. Determination of parent and substituted PAHs in high-fat salmon using a modified QuEChERS extraction, dispersive SPE and GC-MS. J. Agric. Food Chem. 2011, 59, 8108–8116.
7. Sverko E.; et al. Dechlorane plus levels in sediment of the lower Great Lakes. Environ. Sci. Technol. 2008, 42, 361–366.
8. Saito K.; et al. Development of an accelerated solvent extraction and gel permeation chromatography method for measuring persistent organohalogen compounds. Chemosphere 2004, 57, 373–381.
9. Zhao L. Determination of Multiclass, Multiresidue Pesticides in Olive Oil by Captiva EMR—Lipid Cleanup and GC/MS/MS. Agilent Technologies Application Note 2019.
10. Lucas D.; Zhao L. PAH Analysis in Salmon with Enhanced Matrix Removal. Agilent Technologies Application Note 2015.
11. Szelewski M.; Quimby B. Optimized PAH Analysis Using the Agilent Self-Cleaning Ion Source and the Enhanced PAH Analyzer. Agilent Technologies Application Note 2015.