Gerstel: Intelligent Automation for GC/MS and LC.MS

PAHs in Marine Tissue


High Throughput Method for the Determination of PAHs in Seafood by QuEChERS-SBSE-GC-MS

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Keywords: PAH, Seafood, QuEChERS, SBSE, GERSTEL Twister

ABSTRACT

This method uses a QuEChERS (quick, easy, cheap, effective, rugged, and safe) single-step acetonitrile (ACN) extraction and salting out liquid-liquid partitioning to extract PAHs from seafood tissue. Stir Bar Sorptive Extraction (SBSE) is then used as a combined cleanup and concentration step, eliminating organic acids and other polar and high molecular weight matrix components and providing a substantial concentration factor to easily meet regulatory limits of detection and requirements established for precision and accuracy for determination of PAHs in seafood tissue. In brief, 3g of a homogenized seafood tissue sample in water is extracted with ACN in a 50 mL centrifuge tube followed by addition of 6.0 g MgSO4 and 1.5 g sodium acetate which is shaken and centrifuged. A portion of the ACN extract (upper layer) is added to a 10 mL vial with 4 mL 0.1 M NaHCO3 and a GERSTEL Twister™ stir bar and stirred to extract and concentrate the PAHs. The Twister stir bar is transferred to a thermal desorption tube in an autosampler tray for analysis by gas chromatography/mass spectrometry (GC/MS).


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

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Keywords: PAH, Seafood, QuEChERS, SBSE, GERSTEL Twister

ABSTRACT

The Deepwater Horizon oil rig explosion and the subsequent massive oil spill was one of the worst offshore oil catastrophe in United States history and is and impacted fragile ecosystems, air and water quality, and food supplies.

Protecting humans from consuming foods contaminated with oil, while minimizing economical impacts for fisheries, is presenting several challenges. The current protocol for screening seafood harvested from the gulf is organoleptic testing followed by polycyclic aromatic hydrocarbons (PAHs) testing using NOAA Method 2004. It is generally thought that improved testing strategies will be needed to meet state screening requirements. A recent EPA Region 7 study has shown that Stir Bar Sorptive Extraction (SBSE) is an effective and fast technique for trace PAH determination in water. The goal of this study is to determine if using a QuEChERS solvent extraction in conjunction with SBSE can meet regulatory limits of detection and requirements established for precision and accuracy. Preliminary data show linear calibration for PAHs from 1-250 ng/g tissue in matrix matched extracts. Triplicate analyses estimates recoveries at 107 % ± 5 % RSD in fish tissue spiked with 2.5 or 25 ng/g PAH standards. It is also estimated that 40-60 homogenized samples/analyst/day can be analyzed using this improved method.