Determination of chemical contaminants in marine fish by GCMS/ MS using QuEChERS as an extraction method

Significance of the topic

Persistent organic pollutants pose a high risk to human health through bioaccumulation in marine food chains. In regions with uncontrolled industrial and domestic waste discharge, such as coastal India, fish and shellfish may contain trace levels of organochlorine pesticides, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Reliable quantitation of these contaminants at parts‐per‐billion levels is essential for food safety monitoring and regulatory compliance.

Goals and study overview

This work aimed to develop and validate a fast, accurate and reproducible GC-MS/MS method for detecting multiple classes of persistent organic pollutants in prawns. Key objectives included optimizing extraction and cleanup using QuEChERS, establishing multiple reaction monitoring transitions via a smart database, and evaluating method performance parameters such as limit of detection, limit of quantitation, precision and recovery.

Methodology and used instrumentation

Sample preparation

• 10 g finely ground prawn tissue hydrated with water and spiked with target analytes
• Extraction with acetonitrile containing 0.5 % acetic acid and QuEChERS salts (MgSO4 and sodium acetate)
• Cleanup via dispersive SPE tube with MgSO4, PSA and C18 sorbents
• Filtration through 0.2 µm PTFE membrane and 1 µL injection volume

GC-MS/MS analysis

• Instrument Shimadzu GCMS-TQ8040 operated in electron ionization and MRM mode
• Column Rxi-5Sil MS 30 m × 0.25 mm id, 0.25 µm film
• Carrier gas helium at linear velocity 40.2 cm/s
• Temperature program from 70 °C to 280 °C over 45.87 min
• Smart MRM optimization tool used to select precursor and product ions and collision energies

Key results and discussion

The method achieved limits of quantitation of 5 ppb for 90 % of analytes, with RSD values below 15 % at 5 ppb (n = 5). Calibration curves in matrix were linear from 1 to 50 ppb, with r2 above 0.995. Recoveries in prawns ranged from 70 % to 130 % across all analyte classes. High signal-to-noise ratios at LOQ levels confirmed method sensitivity. Chromatographic separation and optimized dwell times ensured reliable quantitation in a complex biological matrix.

Benefits and practical applications

This validated GC-MS/MS protocol enables laboratories to perform routine screening and quantitation of multiple classes of organic contaminants in seafood products. The combination of QuEChERS extraction and smart MRM optimization delivers a balance of speed, cost-effectiveness and analytical rigor suitable for regulatory monitoring, quality assurance and research studies.

Future trends and potential applications

Innovations in high-throughput sample prep and automated MRM optimization will further reduce analysis times and improve sensitivity. Expanding the database to include emerging contaminants and metabolites can broaden surveillance scope. Coupling with isotope dilution calibration and high-resolution mass spectrometry may enhance quantitation accuracy in ultra-trace analysis.

Conclusion

The developed GC-MS/MS method on Shimadzu GCMS-TQ8040 with QuEChERS extraction successfully quantified organochlorine pesticides, PAHs and PCBs in prawn tissue at ppb levels. Smart MRM database tools simplified transition optimization and achieved high precision, linearity and recovery, demonstrating suitability for marine food safety testing.

References

1. Weiss J Paepke O and Bergman A 2005 A worldwide survey of polychlorinated dibenzo-p-dioxins dibenzofurans and related contaminants in butter Ambio 34 22-30
2. Pesticide Residue in Foods by acetonitrile Extraction and Partitioning with magnesium Sulfate AOAC Official Method 2007.01 2007